We gratefully acknowledge support from
the Simons Foundation and University of Wisconsin-Madison Libraries.

Astrophysics

New submissions

[ total of 94 entries: 1-94 ]
[ showing up to 2000 entries per page: fewer | more ]

New submissions for Thu, 16 May 19

[1]  arXiv:1905.05759 [pdf, ps, other]  Coffee Cup
Title: Solar flare forecasting using morphological properties of sunspot groups
Comments: 15 pages. accepted by the "Journal of Space Weather and Space Climate"
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

We describe a new tool developed for solar flare forecasting on the base of some sunspot group properties. Assuming that the flare frequency follows the Poisson statistics, this tool uses a database containing the morphological characteristics of the suspot groups daily observed by the Equatorial Spar of INAF $-$ Catania Astrophysical Observatory since January 2002 up today. By means of a linear combination of the flare rates computed on the base of some properties of the sunspot groups, like area, number of pores and sunspots, Zurich class, relative importance between leading spot and density of the sunspot population, and type of penumbra of the main sunspot, we determine the probability percentages that a flare of a particular energy range may occur. Comparing our forecasts with the flares registered by GOES satellites in the 1$-$8 \AA{} X$-$ray band during the subsequent 24 hrs we measured the performance of our method. We found that this method, which combines some morphological parameters and a statistical technique, has the best performances for the strongest events, which are more interesting for their implications in the Earth environment.

[2]  arXiv:1905.05766 [pdf, other]  Coffee Cup
Title: Predicting the density profiles of the first halos
Comments: 17 pages plus appendices, 19 figures; to be submitted to PRD
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)

The first dark matter halos form by direct collapse from peaks in the matter density field, and evidence from numerical simulations and other analyses suggests that the dense inner regions of these objects largely persist today. These halos would be the densest dark matter structures in the Universe, and their abundance can probe processes that leave imprints on the primordial density field, such as inflation or an early matter-dominated era. They can also probe dark matter through its free-streaming scale. The first halos are qualitatively different from halos that form by hierarchical clustering, as evidenced by their $\rho\propto r^{-3/2}$ inner density profiles. In this work, we present and tune models that predict the density profiles of these halos from properties of the density peaks from which they collapsed. These models predict the coefficient $A$ of the $\rho=Ar^{-3/2}$ small-radius asymptote of the density profile along with the maximum circular velocity $v_\mathrm{max}$ and associated radius $r_\mathrm{max}$. These models are universal: they can be applied to any cosmology, and we confirm this by validating the models using six $N$-body simulations carried out in wildly disparate cosmological scenarios. With their connection to the primordial density field established, the first dark matter halos will serve as probes of the early Universe and the nature of dark matter.

[3]  arXiv:1905.05767 [pdf, other]  Coffee Cup
Title: Deep Neural Network Classifier for Variable Stars with Novelty Detection Capability
Comments: 9 pages, 3 figures, 2 tables. Accepted to ApJ Letters
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)

Common variable star classifiers are built only with the goal of producing the correct class labels, leaving much of the multi-task capability of deep neural networks unexplored. We present a periodic light curve classifier that combines a recurrent neural network autoencoder for unsupervised feature extraction and a dual-purpose estimation network for supervised classification and novelty detection. The estimation network optimizes a Gaussian mixture model in the reduced-dimension feature space, where each Gaussian component corresponds to a variable class. An estimation network with a basic structure of a single hidden layer attains a cross-validation classification accuracy of ~99%, on par with the conventional workhorses, random forest classifiers. With the addition of photometric features, the network is capable of detecting previously unseen types of variability with precision 0.90, recall 0.96, and an F1 score of 0.93. The simultaneous training of the autoencoder and estimation network is found to be mutually beneficial, resulting in faster autoencoder convergence, and superior classification and novelty detection performance. The estimation network also delivers adequate results even when optimized with pre-trained autoencoder features, suggesting that it can readily extend existing classifiers to provide added novelty detection capabilities.

[4]  arXiv:1905.05769 [pdf, other]  Coffee Cup
Title: The Photon Spectrum of Asymmetric Dark Stars
Comments: 8 pages, 6 figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)

Asymmetric Dark Stars, i.e., compact objects formed from the collapse of asymmetric dark matter could potentially produce a detectable photon flux if dark matter particles self-interact via dark photons that kinetically mix with ordinary photons. The morphology of the emitted spectrum is significantly different and therefore distinguishable from a typical black-body one. Given the above and the fact that asymmetric dark stars can have masses outside the range of neutron stars, the detection of such a spectrum can be considered as a smoking gun signature for the existence of these exotic stars.

[5]  arXiv:1905.05770 [pdf, other]  Coffee Cup
Title: Reheating constraints to WIMPflation
Comments: 6 pages, 2 figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)

Analyses of inflation models are usually conducted assuming a specific range---e.g., $N_k \simeq 50-60$--of the number $N_k$ of $e$-folds of inflation. However, the analysis can also be performed by taking into account constraints imposed by the physics of reheating. In this paper, we apply this analysis to a class of "WIMPflation" models in which the inflaton also plays the role of dark matter. Our analysis also updates prior WIMPflation work with more recent Planck 2018 data. With this new analysis, inflaton potentials $V(\phi)=\lambda\phi^4$ and $\lambda \phi_0^4[1-\cos(\phi/\phi_0)]^2$ are ruled out, while $V(\phi)=\lambda \phi_0^4\{1-\exp[-(\phi/\phi_0)^2]\}^2$ is slightly disfavored, and $V(\phi)=\lambda\phi_0^4\tanh^4(\phi/\phi_0)$ is only viable for certain reheating conditions. In addition, we also discuss for the first time the effect of post-reheating entropy production (from, e.g., cosmological phase transitions) in this reheating-physics analysis. When accounted for, it decreases the number of $e$-folds through $\Delta N_k=-(1/3)\ln(1+\gamma)$, where $\gamma\equiv\delta s/s$ is the fractional increase in entropy. We discuss briefly the possible impact of entropy production to inflation-model constraints in earlier work.

[6]  arXiv:1905.05772 [pdf, other]  Coffee Cup
Title: Detecting 21 cm EoR Signal using Drift Scans: Correlation of Time-ordered Visibilities
Comments: 22 pages and 6 figures. Submitted for publication. Comments and suggestions are welcome
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM)

We present a formalism to extract the EoR HI power spectrum for drift scans using radio interferometers. Our main aim is to determine the coherence time scale of time-ordered visibilities. We compute the two-point correlation function of the HI visibilities measured at different times to address this question. We determine, for a given baseline, the decorrelation of the amplitude and the phase of this complex function. Our analysis uses primary beams of four ongoing and future interferometers---PAPER, MWA, HERA, and SKA1-LOW. We identify physical processes responsible for the decorrelation of the HI signal and isolate their impact by making suitable analytic approximations. For large beams (PAPER, MWA) and large baselines the decorrelation is dominated by the rotation of the sky intensity pattern and is proportional to the inverse of the primary beam. For smaller beams (HERA, SKA1-LOW), the translation of the intensity pattern also plays an important role. The decorrelation time of the amplitude of the correlation function lies in the range of 2--20~minutes for baselines of interest for the extraction of the HI signal. The phase angle of the correlation function can be made small after scaling out an appropriate phase term, which also causes the coherence time scale of the phase to be longer than the amplitude of the correlation function. We find that our results are insensitive to the input HI power spectrum and therefore they are directly applicable to the analysis of the drift scan data. We also apply our formalism to a set of point sources and statistically homogeneous diffuse correlated foregrounds. We find that point sources decorrelate on a time scale much shorter than the HI signal. This provides a novel mechanism to partially mitigate foregrounds on the plane of the sky in a drift scan.

[7]  arXiv:1905.05773 [pdf, ps, other]  Coffee Cup
Title: Peculiar outbursts of an ultra luminous source likely signs of an aperiodic disc-wind
Comments: 7 pages, 2 figures, accepted by ApJ
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

The metal rich globular cluster RZ 2109 in the massive Virgo elliptical galaxy NGC 4472 (M49) harbours the ultra luminous X-ray source XMMU 122939.7+075333. Previous studies showed that this source varies between bright and faint phases on timescales of just a few hours. Here, we report the discovery of two peculiar X-ray bursting events that last for about 8 and 3.5 hours separated by about 3 days. Such a recurring X-ray burst-like behaviour has never been observed before. We argue that type-I X-ray bursts or super bursts as well as outburst scenarios requiring a young stellar object are highly unlikely explanations for the observed light curve, leaving an aperiodic disc wind scenario driven by hyper-Eddington accretion as a viable explanation for this new type of X-ray flaring activities.

[8]  arXiv:1905.05777 [pdf, other]  Coffee Cup
Title: A Measurement of the Cosmic Microwave Background Lensing Potential and Power Spectrum from 500 deg$^2$ of SPTpol Temperature and Polarization Data
Comments: 18 pages, 8 figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We present a measurement of the cosmic microwave background (CMB) lensing potential using 500 deg$^2$ of 150 GHz data from the SPTpol receiver on the South Pole Telescope. The lensing potential is reconstructed with signal-to-noise per mode greater than unity at lensing multipoles $L \lesssim 250$, using a quadratic estimator on a combination of CMB temperature and polarization maps. We report measurements of the lensing potential power spectrum in the multipole range of $100< L < 2000$ from sets of temperature-only, polarization-only, and minimum-variance estimators. We measure the lensing amplitude by taking the ratio of the measured spectrum to the expected spectrum from the best-fit $\Lambda$CDM model to the $\textit{Planck}$ 2015 TT+lowP+lensing dataset. For the minimum-variance estimator, we find $A_{\rm{MV}} = 0.944 \pm 0.058{\rm (Stat.)}\pm0.025{\rm (Sys.)}$; restricting to only polarization data, we find $A_{\rm{POL}} = 0.906 \pm 0.090 {\rm (Stat.)} \pm 0.040 {\rm (Sys.)}$. Considering statistical uncertainties alone, this is the most precise polarization-only lensing amplitude constraint to date (10.1 $\sigma$), and is more precise than our temperature-only constraint. We perform null tests and consistency checks and find no evidence for significant contamination.

[9]  arXiv:1905.05780 [pdf, other]  Coffee Cup
Title: Stronger Constraints on the Evolution of the $M_{\rm{BH}}-σ_*$ Relation up to $z\sim0.6$
Comments: Accepted 14 May 2019. 42 pages, 12 figures, 4 tables
Subjects: Astrophysics of Galaxies (astro-ph.GA)

We revisit the possibility of redshift evolution in the $M_{\rm{BH}}-\sigma_*$ relation with a sample of 22 Seyfert 1 galaxies with black holes (BHs) in the mass range $10^{6.3}-10^{8.3}~M_\odot$ and redshift range $0.03<z<0.57$ with spectra obtained from spatially-resolved Keck/LRIS observations. Stellar velocity dispersions were measured directly from the Mg Ib region, taking into consideration the effect of Fe II contamination, AGN dilution, and host-galaxy morphology on our measurements. Black hole masses are estimated using the H$\beta$ line width, and the luminosity at 5100 $\overset{\lower.5em\circ}{\mathrm{A}}$ is estimated from surface brightness decomposition of the active-galactic nucleus (AGN) from the host galaxy using high-resolution imaging from Hubble Space Telescope. Additionally, we investigate the use of [O III]$\lambda5007$ emission line width as a surrogate for stellar velocity dispersion, finding better correlation once corrected for Fe II contamination and any possible blueshifted wing components. Our selection criteria allowed us to probe lower-luminosity AGN and lower-mass BHs in the non-local universe than those measured in previous single-epoch studies. We find that any offset in the $M_{\rm{BH}}-\sigma_*$ relation up to $z\sim0.6$ is consistent with the scatter of local BH masses, and address the sources of biases and uncertainties that contribute to this scatter.

[10]  arXiv:1905.05794 [pdf, other]  Coffee Cup
Title: Evidence of Systematic Errors in $Spitzer$ Microlens Parallax Measurements
Comments: 29 pages, 7 figures, 3 tables, submitted to AJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

The microlensing parallax campaign with the $Spitzer$ space telescope aims to measure masses and distances of microlensing planetary events seen towards the Galactic bulge. The hope is to measure how the distribution of planets depends on position within the Galaxy. In this paper, we compare 50 microlens parallax measurements from 2015 $Spitzer$ campaign to three different Galactic models commonly used in microlensing analyses, and we find that $\geq 80\,$\% of these events have microlensing parallax values higher than the medians predicted by Galactic models. We use the Anderson-Darling (AD) and Kolmogorov-Smirnov (KS) tests on the distributions of the prior probability that the each of the $Spitzer$ parallax measurements is at least as large as the observed microlensing parallax values. These tests indicate probabilities of $p_{\rm AD} < 3.0 \times 10^{-8}$ and $p_{\rm KS} < 4.1 \times 10^{-6}$ that the data are consistent with these Galactic models from the AD and KS tests respectively. Given that many $Spitzer$ light curves show evidence of large correlated errors, we conclude that this discrepancy is probably due to systematic errors in the $Spitzer$ photometry. We consider a simple scheme to correct for this problem by multiplying the reported error bars on the $Spitzer$ microlensing parallax measurements by a constant factor, and we find that an error bar renormalization factor of 3.4 provides reasonable agreement with all three Galactic models. We expect, however, that corrections to the uncertainties in the $Spitzer$ photometry itself are likely to be a more effective way to address the systematic errors. We also argue that is important to include the ${\bm \pi_{\rm E}}$ prior distributions when analyzing events with large uncertainties or degeneracies in ${\bm \pi_{\rm E}}$ measurements.

[11]  arXiv:1905.05798 [pdf, other]  Coffee Cup
Title: Solving the gamma-ray radiative transfer equation for supernovae
Comments: 9 pages, 7 figures. Accepted for publication in MNRAS
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

We present a new relativistic radiative-transfer code for $\gamma$-rays of energy less than 5 MeV in supernova (SN) ejecta. This code computes the opacities, the prompt emissivity (i.e. decay), and the scattering emissivity, and solves for the intensity in the co-moving frame. Because of the large expansion velocities of SN ejecta, we ignore redistribution effects associated with thermal motions. The energy deposition is calculated from the energy removed from the radiation field by scattering or photoelectric absorption. This new code yields comparable results to an independent Monte Carlo code. However, both yield non-trivial differences with the results from a pure absorption treatment of $\gamma$-ray transport. A synthetic observer's frame spectrum is also produced from the CMF intensity. At early times when the optical depth to $\gamma$-rays is large, the synthetic spectrum show asymmetric line profiles with redshifted absorption as seen in SN 2014J. This new code is integrated within CMFGEN and allows for an accurate and fast computation of the decay energy deposition in SN ejecta.

[12]  arXiv:1905.05808 [pdf]  Coffee Cup
Title: The Radio Universe at Low Surface Brightness: Feedback & accretion in the circumgalactic medium
Authors: Bjorn Emonts (1), Mark Lacy (1), Kristina Nyland (2), Brian Mason (1), Matthew Lehnert (3), Chris Carilli (1), Craig Sarazin (4), Zheng Cai (5,6), Suchetana Chatterjee (7), Helmut Dannerbauer (8), John Gallagher (9), Kevin Harrington (10,11), Desika Naryanan (12,13), Dominik Riechers (14,11), Graca Rocha (15) ((1) NRAO, (2) NRC, resident at NRL, (3) IAP, (4) Univ. Virginia, (5) Tsinghua Univ., (6) Lick Obs., (7) Presidency Univ., (8) IAC, (9) Univ. Wisconsin-Madison, (10) Univ. Bonn, (11) MPI, (12) Univ. Florida, (13) Univ. Copenhagen, (14) Cornell Univ., (15) JPL)
Comments: Science White paper submitted to Astro2020 Decadal Survey
Subjects: Astrophysics of Galaxies (astro-ph.GA)

Massive galaxies at high-z are known to co-evolve with their circumgalactic medium (CGM). If we want to truly understand the role of the CGM in the early evolution of galaxies and galaxy-clusters, we need to fully explore the multi-phase nature of the CGM. We present two novel science cases that utilize low-surface-brightness observations in the radio regime to better understand the CGM around distant galaxies. At the lowest temperatures, observations of widespread molecular gas are providing evidence for the cold baryon cycle that grows massive galaxies. At the highest temperatures, observations of the Sunyaev-Zeldovich Effect are starting to reveal the effect of quasar feedback onto the hot gas in the CGM. We discuss the critical role that radio interferometers with compact configurations in the millimeter regime will play over the next decade in understanding the crucial role of the multi-phase CGM in galaxy evolution.

[13]  arXiv:1905.05815 [pdf, ps, other]  Coffee Cup
Title: Investigating the origin of the spectral line profiles of the Hot Wolf-Rayet Star WR2
Comments: 12 pages, 9 figures
Journal-ref: MNRAS, 484, 5834 (2019)
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

The hot WN star WR2 (HD6327) has been claimed to have many singular characteristics. To explain its unusually rounded and relatively weak emission line profiles, it has been proposed that WR2 is rotating close to break-up with a magnetically confined wind. Alternatively, the line profiles could be explained by the dilution of WR2's spectrum by that of a companion. In this paper, we present a study of WR2 using near-infrared AO imaging and optical spectroscopy and polarimetry. Our spectra reveal the presence of weak photospheric absorption lines from a ~B2.5-4V companion, which however contributes only ~5-10% to the total light, suggesting that the companion is a background object. Therefore, its flux cannot be causing any significant dilution of the WR star's emission lines. The absence of intrinsic linear continuum polarization from WR2 does not support the proposed fast rotation. Our Stokes V spectrum was not of sufficient quality to test the presence of a moderately strong organized magnetic field but our new modelling indicates that to confine the wind the putative magnetic field must be significantly stronger than was previously suggested sufficiently strong as to make its presence implausible.

[14]  arXiv:1905.05821 [pdf, other]  Coffee Cup
Title: A Chromaticity Analysis and PSF Subtraction Techniques for SCExAO/CHARIS data
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)

We present an analysis of instrument performance using new observations taken with the Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS) instrument and the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system. In a correlation analysis of our datasets (which use the broadband mode covering J through K band in a single spectrum), we find that chromaticity in the SCExAO/CHARIS system is generally worse than temporal stability. We also develop a point spread function (PSF) subtraction pipeline optimized for the CHARIS broadband mode, including a forward modelling-based exoplanet algorithmic throughput correction scheme. We then present contrast curves using this newly developed pipeline. An analogous subtraction of the same datasets using only the H band slices yields the same final contrasts as the full JHK sequences; this result is consistent with our chromaticity analysis, illustrating that PSF subtraction using spectral differential imaging (SDI) in this broadband mode is generally not more effective than SDI in the individual J, H, or K bands. In the future, the data processing framework and analysis developed in this paper will be important to consider for additional SCExAO/CHARIS broadband observations and other ExAO instruments which plan to implement a similar integral field spectrograph broadband mode.

[15]  arXiv:1905.05826 [pdf, other]  Coffee Cup
Title: The fundamental metallicity relation emerges from the local anti-correlation between star formation rate and gas-phase metallicity existing in disk galaxies
Authors: J. Sanchez Almeida (1,2), L.Sanchez-Menguiano (1,2) ((1) Instituto de Astrofisica de Canarias, La Laguna, Tenerife, Spain, (2) Departamento de Astrofisica, Universidad de La Laguna, Tenerife, Spain)
Comments: Accepted for publication in ApJL. 6 pages and 3 figures
Subjects: Astrophysics of Galaxies (astro-ph.GA)

The fundamental metallicity relation (FMR) states that galaxies of the same stellar mass but larger star formation rate (SFR) tend to have smaller gas-phase metallicity (<Zg>). It is thought to be fundamental because it naturally arises from the stochastic feeding of star-formation from external metal-poor gas accretion, a process extremely elusive to observe but essential according the cosmological simulations of galaxy formation. In this letter, we show how the FMR emerges from the local anti-correlation between SFR surface density and Zg recently observed to exist in disk galaxies. We analytically derive the global FMR from the local law, and then show that both relations agree quantitatively when considering the star-forming galaxies of the MaNGA survey. Thus, understanding the FMR becomes equivalent to understanding the origin of the anti-correlation between SFR and metallicity followed by the set of star-forming regions of any typical galaxy. The correspondence between local and global laws is not specific of the FMR, so that a number of local relations should exist associated with known global relations.

[16]  arXiv:1905.05829 [pdf, other]  Coffee Cup
Title: Modeling the Protoplanetary Disks of Two Brown Dwarfs in the Taurus Molecular Cloud
Comments: 16 pages, 6 figures. Accepted to ApJ on May 10, 2019
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

Measuring the properties of protoplanetary disks around brown dwarfs is central to understanding the formation of brown dwarfs and their planetary companions. We present modeling of CFHT Tau 4 and 2M0444, two brown dwarfs with protoplanetary disks in the Taurus Molecular Cloud. By combining modeling of the spectral energy distributions and ALMA images, we obtain disk radii and masses for these objects; these parameters can be used to constrain brown dwarf formation and planet formation, respectively. We find that the disk around CFHT Tau 4 has a mass of 0.42 M$_{Jup}$ and a radius of 80 au; we find 2M0444's disk to have a mass of 2.05 M$_{Jup}$ and a radius of 100 au. These radii are more consistent with those predicted by theoretical simulations of brown dwarf formation via undisturbed condensation from a mass reservoir than those predicted by ejection from the formation region. Furthermore, the disk mass of 2M0444 suggests that planet formation may be possible in this disk, although the disk of 2M0444 is likely not massive enough to form planets. The disk properties measured here provide constraints to theoretical models of brown dwarf formation and the formation of their planetary companions.

[17]  arXiv:1905.05832 [pdf, other]  Coffee Cup
Title: Visual binary stars with partially missing data: Introducing multiple imputation in astrometric analysis
Comments: Nine figures, six tables. Accepted for publication in PASP. First mention and explicit application of imputation technique in Astronomy
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR); Data Analysis, Statistics and Probability (physics.data-an)

Partial measurements of relative position are a relatively common event during the observation of visual binary stars. However, these observations are typically discarded when estimating the orbit of a visual pair. In this article we present a novel framework to characterize the orbits from a Bayesian standpoint, including partial observations of relative position as an input for the estimation of orbital parameters. Our aim is to formally incorporate the information contained in those partial measurements in a systematic way into the final inference. In the statistical literature, an imputation is defined as the replacement of a missing quantity with a plausible value. To compute posterior distributions of orbital parameters with partial observations, we propose a technique based on Markov chain Monte Carlo with multiple imputation. We present the methodology and test the algorithm with both synthetic and real observations, studying the effect of incorporating partial measurements in the parameter estimation. Our results suggest that the inclusion of partial measurements into the characterization of visual binaries may lead to a reduction in the uncertainty associated to each orbital element, in terms of a decrease in dispersion measures (such as the interquartile range) of the posterior distribution of relevant orbital parameters. The extent to which the uncertainty decreases after the incorporation of new data (either complete or partial) depends on how informative those newly-incorporated measurements are. Quantifying the information contained in each measurement remains an open issue.

[18]  arXiv:1905.05846 [pdf, other]  Coffee Cup
Title: Fast Wiener filtering of CMB maps with Neural Networks
Comments: 15 pages, 7 figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM)

We show how a neural network can be trained to Wiener filter masked CMB maps to high accuracy. We propose an innovative neural network architecture, the WienerNet, which guarantees linearity in the data map. Our method does not require Wiener filtered training data, but rather learns Wiener filtering from tailored loss functions which are mathematically guaranteed to be minimized by the exact solution. Once trained, the neural network Wiener filter is extremely fast, about a factor of 1000 faster than the standard conjugate gradient method. Wiener filtering is the computational bottleneck in many optimal CMB analyses, including power spectrum estimation, lensing and non-Gaussianities, and our method could potentially be used to speed them up by orders of magnitude with minimal loss of optimality. The method should also be useful to analyze other statistical fields in cosmology.

[19]  arXiv:1905.05862 [pdf, other]  Coffee Cup
Title: Optimizing Ground-based Observations of O2 in Earth Analogs
Comments: 15 pages, 7 figures, accepted for publication in The Astronomical Journal
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

We present the result of calculations to optimize the search for molecular oxygen (O2) in Earth analogs transiting around nearby, low-mass stars using ground-based, high-resolution, Doppler shift techniques. We investigate a series of parameters, namely spectral resolution, wavelength coverage of the observations, and sky coordinates and systemic velocity of the exoplanetary systems, to find the values that optimize detectability of O2. We find that increasing the spectral resolution of observations to R = 300,000 - 400,000 from the typical R ~ 100,000, more than doubles the average depth of O2 lines in planets with atmospheres similar to Earth's. Resolutions higher than about 500,000 do not produce significant gains in the depths of the O2 lines. We confirm that observations in the O2 A-band are the most efficient except for M9V host stars, for which observations in the O2 NIR-band are more efficient. Combining observations in the O2 A, B, and NIR -bands can reduce the number of transits needed to produce a detection of O2 by about 1/3 in the case of white noise limited observations. However, that advantage disappears in the presence of typical levels of red noise. Therefore, combining observations in more than one band produces no significant gains versus observing only in the A-band, unless red-noise can be significantly reduced. Blending between the exoplanet's O2 lines and telluric O2 lines is a known problem. We find that problem can be alleviated by increasing the resolution of the observations, and by giving preference to targets near the ecliptic.

[20]  arXiv:1905.05870 [pdf, other]  Coffee Cup
Title: Orbital stability in the Solar System for arbitrary inclinations and eccentricities: planetary perturbations versus resonances
Authors: Tabare Gallardo
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

Applying the technique of dynamical maps we study the orbital stability of test particles in the Solar System in the space (a,e,i) defined by 0.1<a<38 au, 0<e<0.9 and 0<i<180 identifying the unstable and stable regions. We find stable niches where small bodies can survive even for very high eccentricities. Mean motion resonances play a fundamental role providing stability against the planetary perturbations specially for high inclination orbits. A stability stripe around i=150 is present all along the Solar System. We found that the population of objects with semimajor axes between 10 and 30 au is evolving inside a highly unstable region according to our maps. For the inner Solar System we found that the region between the Hildas and Jupiter is more stable for high eccentricity orbits than for low eccentricity ones.

[21]  arXiv:1905.05873 [pdf, ps, other]  Coffee Cup
Title: $Spitzer$ Parallax of OGLE-2018-BLG-0596: A Low-mass-ratio Planet around an M-dwarf
Comments: 34 pages, 8 figures, Submitted to AAS journal
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

We report the discovery of a $Spitzer$ microlensing planet OGLE-2018-BLG-0596Lb, with preferred planet-host mass ratio $q \sim 2\times10^{-4}$. The planetary signal, which is characterized by a short $(\sim 1~{\rm day})$ "bump" on the rising side of the lensing light curve, was densely covered by ground-based surveys. We find that the signal can be explained by a bright source that fully envelops the planetary caustic, i.e., a "Hollywood" geometry. Combined with the source proper motion measured from $Gaia$, the $Spitzer$ satellite parallax measurement makes it possible to precisely constrain the lens physical parameters. The preferred solution, in which the planet perturbs the minor image due to lensing by the host, yields a Uranus-mass planet with a mass of $M_{\rm p} = 13.9\pm1.6~M_{\oplus}$ orbiting a mid M-dwarf with a mass of $M_{\rm h} = 0.23\pm0.03~M_{\odot}$. There is also a second possible solution that is substantially disfavored but cannot be ruled out, for which the planet perturbs the major image. The latter solution yields $M_{\rm p} = 1.2\pm0.2~M_{\oplus}$ and $M_{\rm h} = 0.15\pm0.02~M_{\odot}$. By combining the microlensing and $Gaia$ data together with a Galactic model, we find in either case that the lens lies on the near side of the Galactic bulge at a distance $D_{\rm L} \sim 6\pm1~{\rm kpc}$. Future adaptive optics observations may decisively resolve the major image/minor image degeneracy.

[22]  arXiv:1905.05875 [pdf, ps, other]  Coffee Cup
Title: Multiwavelength radio observations of a Brightest Cluster Galaxy at z=1.71: Detection of a modest Active Galactic Nucleus and evidence for extended star formation
Comments: 8 pages, 4 figures, MNRAS accepted
Subjects: Astrophysics of Galaxies (astro-ph.GA)

We present deep, multiwavelength radio observations of SpARCS104922.6+564032.5, a z = 1.71 galaxy cluster with a starbusting core. Observations were made with the Karl G. Jansky Very Large Array (JVLA) in 3 bands: 1-2 GHz, 4-8 GHz and 8-12 GHz. We detect a radio source coincident with the Brightest Cluster Galaxy (BCG) that has a spectral index of {\alpha}=0.44\pm 0.29 and is indicative of emission from an Active Galactic Nucleus. The radio luminosity is consistent with the average luminosity of the lower redshift BCG sample, but the flux densities are 6{\sigma} below the predicted values of the star-forming Spectral Energy Distribution based on far infrared data. Our new fit fails to simultaneously describe the far infrared and radio fluxes. This, coupled with the fact that no other bright source is detected in the vicinity of the BCG implies that the star formation region, traced by the infrared emission, is extended or clumpy and not located directly within the BCG. Thus, we suggest that the star-forming core might not be driven by a single major wet merger, but rather by several smaller galaxies stripped of their gas or by a displaced cooling flow, although more data are needed to confirm any of those scenarios.

[23]  arXiv:1905.05900 [pdf, ps, other]  Coffee Cup
Title: Kepler Planet Occurrence Rates for Mid-Type M Dwarfs as a Function of Spectral Type
Comments: 35 pages, 10 figures, 4 tables, Accepted for publication in AJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

Previous studies of planet occurrence rates largely relied on photometric stellar characterizations. In this paper, we present planet occurrence rates for mid-type M dwarfs using spectroscopy, parallaxes, and photometry to determine stellar characteristics. Our spectroscopic observations have allowed us to constrain spectral type, temperatures, and in some cases metallicities for 337 out of 561 probable mid-type M dwarfs in the primary Kepler field. We use a random forest classifier to assign a spectral type to the remaining 224 stars. Combining our data with Gaia parallaxes, we compute precise ($\sim$3%) stellar radii and masses, which we use to update planet parameters and planet occurrence rates for Kepler mid-type M dwarfs. Within the Kepler field, there are seven M3 V to M5 V stars which host 13 confirmed planets between 0.5 and 2.5 Earth radii and at orbital periods between 0.5 and 10 days. For this population, we compute a planet occurrence rate of $1.19^{+0.70}_{-0.49}$ planets per star. For M3 V, M4 V, and M5 V, we compute planet occurrence rates of $0.86^{+1.32}_{-0.68}$, $1.36^{+2.30}_{-1.02}$, and $3.07^{+5.49}_{-2.49}$ planets per star, respectively.

[24]  arXiv:1905.05905 [pdf, ps, other]  Coffee Cup
Title: Polarization of Astrophysical Events with Precessing Jets
Comments: 21 pages, 6 figures, accepted by ApJ
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)

A central compact object (CCO, e.g. a black hole) with an accretion disk has been suggested as the common central engine of various astrophysical phenomena, such as gamma-ray bursts (GRBs), tidal disruption events (TDEs) and active galactic nuclei (AGNs). A jet powered by such a system might precess due to the misalignment of the angular momenta of the CCO and accretion disk. Some quasi-periodic behaviors observed in the light curves of these phenomena can be well interpreted within the framework of a precessing jet model. In this paper, we study the emission polarization of precessing jets in the three kinds of phenomena. The polarization angle also shows a gradual change for the synchrotron emission in both the random and toroidal magnetic field configurations with the precessing jet, while it can only change abruptly by $90^\circ$ for the non-precessing top-hat jet. Polarization properties are periodic due to the assumptions made in our model. The polarization observations are crucial to confirm the precession nature of jets in GRBs, TDEs and AGNs.

[25]  arXiv:1905.05907 [pdf, other]  Coffee Cup
Title: Roles of crust and core in the tidal deformability of neutron stars
Comments: 5 pages, 5 figures
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)

With the recent measurement of GW170817 providing constraints on the tidal deformability of a neutron star, it is very important to understand what features of the equation of state have the biggest effect on it. We therefore study the contribution of the crust to the tidal deformability and the moment of inertia of a neutron star for a variety of well-known equations of state. It is found that the contributions to these quantities from the low density crust are typically quite small and as a result the determination of the tidal deformability provides an important constraint on the equation of state of dense matter.

[26]  arXiv:1905.05915 [pdf, ps, other]  Coffee Cup
Title: Lijiang 2.4-meter Telescope and its Instruments
Comments: 20 pages, 14 figures, accepted by Research in Astronomy and Astrophysics(RAA)
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)

Lijiang 2.4-meter Telescope(LJT), the largest common-purpose optical telescope in China, has been applied to the world-wide astronomers since 2008. It is located at Gaomeigu site, Lijiang Observatory(LJO), the southwest of China. The site has very good observational conditions. Since 10-year operation, several instruments have been equipped on the LJT. Astronomers can perform both photometric and spectral observations. The main scientific goals of LJT include photometric and spectral evolution of supernova, reverberation mapping of active galactic nucleus, physical properties of binary star and near-earth object(comet and asteroid), identification of exoplanet, and all kinds of transients. Until now, the masses of 41 high accretion rate black holes have been measured, and more than 168 supernova have been identified by the LJT. More than 190 papers related to the LJT have been published. In this paper, the general observation condition of the Gaomeigu site is introduced at first. Then, the LJT structure is described in detail, including the optical, mechanical, motion and control system. The specification of all the instruments, and some detailed parameters of the YFOSC is also presented. Finally, some important scientific results and future expectations are summarized.

[27]  arXiv:1905.05962 [pdf]  Coffee Cup
Title: The Apache Point Observatory Catalog of Optical Diffuse Interstellar Bands
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)

Aiming for a new and more comprehensive DIB catalog between 4,000 and 9,000{\AA}, we revisited the Atlas Catalog based on the observations of HD 183143 and HD 204827 (Hobbs et al. 2008 and 2009). Twenty-five medium-to-highly reddened sight lines were selected, sampling a variety of spectral types of the background star and the interstellar environments. The median SNR of these spectra is ~ 1,300 around 6,400{\AA}. Compared to the Atlas Catalog, 22 new DIBs were found, and the boundaries of 27 (sets) of DIBs were adjusted, resulting in an updated catalog containing 559 DIBs that we refer to as the Apache Point Observatory Catalog of Optical Diffuse Interstellar Bands. Measurements were then made based on this catalog. We found our survey most sensitive between 5,500 and 7,000{\AA} due largely to the local SNR of the spectra, the relative absence of interfering stellar lines, and the weakness of telluric residuals. For our data sample, the number of DIBs detected in a given sight line is mostly dependent on EB-V and less on the spectral type of the background star. Some dependence on fH2 is observed, but less well-determined due to the limited size of the data sample. The variations of the wavelengths of each DIB in different sight lines are generally larger than those of the known interstellar lines CH+, CH, and K I. Those variations could be due to the inherent error in the measurement, or to differences in the velocity components among sight lines.

[28]  arXiv:1905.05991 [pdf, ps, other]  Coffee Cup
Title: Magnetic ionization-thermal instability
Comments: 11 pages, 9 figures, 2 tables, accepted for publication in MNRAS
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Plasma Physics (physics.plasm-ph)

Linear analysis of the stability of diffuse clouds in the cold neutral medium with uniform magnetic field is performed. We consider that gas in equilibrium state is heated by cosmic rays, X-rays and electronic photoeffect on the surface of dust grains, and it is cooled by the collisional excitation of fine levels of the CII. Ionization by cosmic rays and radiative recombinations is taken into account. A dispersion equation is solved analytically in the limiting cases of small and large wave numbers, as well as numerically in the general case. In particular cases the dispersion equation describes thermal instability of Field (1965) and ionization-coupled acoustic instability of Flannery and Press (1979). We pay our attention to magnetosonic waves arising in presence of magnetic field, in thermally stable region, $35 \leq T \leq 95$ K and density $n\lessapprox 10^3\,\mbox{cm}^{-3}$. We have shown that these modes can be unstable in the isobarically stable medium. The instability mechanism is similar to the mechanism of ionization-coupled acoustic instability. We determine maximum growth rates and critical wavelengths of the instability of magnetosonic waves depending on gas temperature, magnetic field strength and the direction of wave vector with respect to the magnetic field lines. The minimum growth time of the unstable slow magnetosonic waves in diffuse clouds is of $4-60$ Myr, minimum and the most unstable wavelengths lie in ranges $0.05-0.5$ and $0.5-5$ pc, respectively. We discuss the application of considered instability to the formation of small-scale structures and the generation of MHD turbulence in the cold neutral medium.

[29]  arXiv:1905.05993 [pdf, ps, other]  Coffee Cup
Title: Stellar Wind Accretion and Raman Scattered O VI Features in the Symbiotic Star AG Draconis
Comments: 12 pages, 10 figures, Accepted for publication in MNRAS
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

We present high resolution spectroscopy of the yellow symbiotic star AG Draconis with ESPaDOnS at the {\it Canada-France-Hawaii Telescope}. Our analysis is focused on the profiles of Raman scattered \ion{O}{VI} features centered at 6825 \AA\ and 7082 \AA, which are formed through Raman scattering of \ion{O}{VI}$\lambda\lambda$1032 and 1038 with atomic hydrogen. These features are found to exhibit double component profiles with conspicuously enhanced red parts. Assuming that the \ion{O}{vi} emission region constitutes a part of the accretion flow around the white dwarf, Monte Carlo simulations for \ion{O}{VI} line radiative transfer are performed to find that the overall profiles are well fit with the accretion flow azimuthally asymmetric with more matter on the entering side than on the opposite side. As the mass loss rate of the giant component is increased, we find that the flux ratio $F(6825)/F(7082)$ of Raman 6825 and 7082 features decreases and that our observational data are consistent with a mass loss rate $\dot M\sim 2 \times 10^{-7} {\rm\ M_{\odot}\ yr^{-1}}$. We also find that additional bipolar components moving away with a speed $\sim 70{\rm\ km\ s^{-1}}$ provide considerably improved fit to the red wing parts of Raman features. The possibility that the two Raman profiles differ is briefly discussed in relation to the local variation of the \ion{O}{VI} doublet flux ratio.

[30]  arXiv:1905.05996 [pdf, ps, other]  Coffee Cup
Title: A model for the radio/X-ray correlation in three neutron star low-mass X-ray binaries 4U 1728-34, Aql X-1 and EXO 1745-248
Authors: Erlin Qiao (NAOC), B.F. Liu (NAOC)
Comments: 8 pages, 5 figures; Accepted for publication by MNRAS
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

Observationally, for neutron star low-mass X-ray binaries, so far, the correlation between the radio luminosity $L_{\rm R}$ and the X-ray luminosity $L_{\rm X}$, i.e., $L_{\rm R}\propto L_{\rm X}^{\beta}$, has been reasonably well-established only in three sources 4U 1728-34, Aql X-1 and EXO 1745-248 in their hard state. The slope $\beta$ of the radio/X-ray correlation of the three sources is different, i.e., $\beta \sim 1.4$ for 4U 1728-34, $\beta \sim 0.4$ for Aql X-1, and $\beta \sim 1.6$ for EXO 1745-248. In this paper, for the first time we explain the different radio/X-ray correlation of 4U 1728-34, Aql X-1 and EXO 1745-248 with the coupled advection-dominated accretion (ADAF)-jet model respectively. We calculate the emergent spectrum of the ADAF-jet model for $L_{\rm X}$ and $L_{\rm R}$ at different $\dot m$ ($\dot m=\dot M/\dot M_{\rm Edd}$), adjusting $\eta$ ($\eta \equiv \dot M_{\rm jet}/\dot M$, describing the fraction of the accreted matter in the ADAF transfered vertically forming the jet) to fit the observed radio/X-ray correlations. Then we derive a fitting formula of $\eta$ as a function of $\dot m$ for 4U 1728-34, Aql X-1 and EXO 1745-248 respectively. If the relation between $\eta$ and $\dot m$ can be extrapolated down to a lower value of $\dot m$, we find that in a wide range of $\dot m$, the value of $\eta$ in Aql X-1 is greater than that of in 4U 1728-34 and EXO 1745-248, implying that Aql X-1 may have a relatively stronger large-scale magnetic field, which is supported by the discovery of the coherent millisecond X-ray pulsation in Aql X-1.

[31]  arXiv:1905.06017 [pdf, other]  Coffee Cup
Title: The ALMA Discovery of the Rotating Disk and Fast Outflow of Cold Molecular Gas in NGC~1275
Comments: 17 pages, 16 figures. Submitted to ApJ. Received first referee comments
Subjects: Astrophysics of Galaxies (astro-ph.GA)

We present ALMA Band 6 observations of the CO(2-1), HCN(3-2), and HCO$^{+}$(3-2) lines in the nearby radio galaxy / brightest cluster galaxy (BCG) of NGC~1275 with the spatial resolution of $\sim20$~pc. In the previous observations, CO(2-1) emission was detected as radial filaments lying in the east-west direction. We resolved the inner filament and found that the filament cannot be represented by a simple infalling stream both morphologically and kinematically. The observed complex nature of the filament resembles the cold gas structure predicted by recent numerical simulations of cold chaotic accretion. A crude estimate suggests that the accretion rate of the cold gas can be higher than that of hot gas. Within the central 100~pc, we detected a rotational disk of the molecular gas whose mass is $\sim10^{8}~M_{\sun}$. This is the first evidence of the presence of massive cold gas disk on this spatial scale for BCGs. The disk rotation axis is approximately consistent with the axis of the radio jet on subpc scales. This probably suggests that the cold gas disk is physically connected to the innermost accretion disk which is responsible for jet launching. We also detected absorption features in the HCN(3-2) and HCO$^{+}$(3-2) spectra against the radio continuum emission mostly radiated by $\sim1.2$-pc size jet. The absorption features are blue-shifted from the systemic velocity by $\sim$300-600~km~s$^{-1}$, which suggests the presence of outflowing gas from the active galactic nucleus (AGN). We discuss the relation of the AGN feeding with cold accretion, the origin of blue-shifted absorption, and estimate of black hole mass using the molecular gas dynamics.

[32]  arXiv:1905.06025 [pdf, ps, other]  Coffee Cup
Title: Common envelope to explosion delay time of type Ia supernovae
Authors: Noam Soker (Technion, Israel)
Comments: To be submitted in 2 days to allow comments by readers
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

I study the rate of type Ia supernovae (SNe Ia) within about a million years after the assumed common envelope evolution (CEE) that forms the progenitors of these SNe Ia, and find that the population of SNe Ia with short CEE to explosion delay (CEED) time is few times 0.1 of all SNe Ia. I also claim for an expression for the rate of these SNe Ia that occur at short times after the CEE, t<10^6 yr, that is different from that of the delay time distribution (DTD) billions of years after star formation. This tentatively hints that the physical processes that determine the short CEED times are different (at least to some extend) from those that determine the DTD at billions of years. To reach these conclusions I examine SNe Ia that interact with a circumstellar matter (CSM) within months after explosion, so called SNe Ia-CSM, and the rate of SNe Ia that on a time scale of tens to hundreds of years interact with a CSM that might have been a planetary nebula, so called SNe Ia inside a planetary nebula (SNIPs). I assume that the CSM in these populations results from a CEE, and hence this study is relevant mainly to the core degenerate (CD) scenario, to the double degenerate (DD) scenario, and to the double detonation (DDet) scenario with white dwarf companions.

[33]  arXiv:1905.06035 [pdf, other]  Coffee Cup
Title: Ground-based follow-up observations of TRAPPIST-1 transits in the near-infrared
Comments: accepted for publication in MNRAS
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

The TRAPPIST-1 planetary system is a favorable target for the atmospheric characterization of temperate earth-sized exoplanets by means of transmission spectroscopy with the forthcoming James Webb Space Telescope (JWST). A possible obstacle to this technique could come from the photospheric heterogeneity of the host star that could affect planetary signatures in the transit transmission spectra. To constrain further this possibility, we gathered an extensive photometric data set of 25 TRAPPIST-1 transits observed in the near-IR J band (1.2 $\mu$m) with the UKIRT and the AAT, and in the NB2090 band (2.1 $\mu$m) with the VLT during the period 2015-2018. In our analysis of these data, we used a special strategy aiming to ensure uniformity in our measurements and robustness in our conclusions. We reach a photometric precision of $\sim0.003$ (RMS of the residuals), and we detect no significant temporal variations of transit depths of TRAPPIST-1 b, c, e, and g over the period of three years. The few transit depths measured for planets d and f hint towards some level of variability, but more measurements will be required for confirmation. Our depth measurements for planets b and c disagree with the stellar contamination spectra originating from the possible existence of bright spots of temperature 4500 K. We report updated transmission spectra for the six inner planets of the system which are globally flat for planets b and g and some structures are seen for planets c, d, e, and f.

[34]  arXiv:1905.06036 [pdf, ps, other]  Coffee Cup
Title: Robust profile decomposition for large extragalactic spectral-line surveys
Comments: 14 pages, 11 figures
Journal-ref: MNRAS 485, 5021 (2019)
Subjects: Astrophysics of Galaxies (astro-ph.GA)

We present a novel algorithm that is based on a Bayesian Markov Chain Monte Carlo (MCMC) technique for performing robust profile analysis of a data cube from either single-dish or interferometric radio telescopes. It fits a set of models comprised of a number of Gaussian components given by the user to individual line-of-sight velocity profiles, then compares them and finds an optimal model based on the Bayesian Inference Criteria computed for each model.The decomposed Gaussian components are then classified into bulk or non-circular motions as well as kinematically cold or warm components. The fitting based on the Bayesian MCMC technique is insensitive to initial estimates of the parameters, and suffers less from finding the global minimum in models given enough sampling points and a wide range of priors for the parameters. It is found to provide reliable profile decomposition and classification of the decomposed components in a fully automated way, together with robust error estimation of the parameters as shown by performance tests using artificial data cubes. We apply the newly developed algorithm to the HI data cubes of sample galaxies from the Local Volume HI galaxy Survey (LVHIS). We also compare the kinematically cold and warm components, and bulk velocity fields with previous analyses made in a classical method.

[35]  arXiv:1905.06046 [pdf]  Coffee Cup
Title: Towards high-resolution astronomical imaging
Comments: 6 pages, 7 figures, 11 contributors
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)

This paper is a report from a recent meeting on "the Future of high-resolution imaging in the visible and infrared", reviewing the astronomical drivers for development and the technological advances that might boost performance. Each of the authors listed contributed a section themselves.

[36]  arXiv:1905.06050 [pdf, other]  Coffee Cup
Title: Induced Gravitational Collapse, Binary-Driven Hypernovae, Long Gramma-ray Bursts and Their Connection with Short Gamma-ray Bursts
Comments: Invited Review Published by Universe as part of the Special Issue Accretion Disks, Jets, Gamma-Ray Bursts and Related Gravitational Waves. Abstract modified to fulfill the arXiv number limit of characters
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)

Short and long Gamma-ray bursts (GRBs) originate in subclasses with specific energy release, spectra, duration, etc, and have binary progenitors. We review here the binary-driven hypernovae (BdHNe) subclass whose progenitor is a CO$_\textrm{core}$-neutron star (NS). The supernova (SN) explosion of the CO$_\textrm{core}$ produces at its center a new NS ($\nu$NS) and triggers a hypercritical accretion onto the NS. The NS can become a more massive NS or collapse into a black hole (BH). We summarize this topic from the first analytic estimates in 2012 to the most recent three-dimensional (3D) smoothed-particle-hydrodynamics (SPH) numerical simulations in 2018. Long GRBs are richer and more complex than previously thought. The SN and the accretion explain X-ray precursors. The NS accretion, its collapse and the BH formation produce asymmetries in the SN ejecta, implying a 3D GRB analysis. The newborn BH surrounded by the ejecta and the magnetic field inherited from the NS, are the \emph{inner engine} from which the electron-positron ($e^+e^-$) plasma and the high-energy emission initiate. The $e^+e^-$ impact on the ejecta converts the SN into a hypernova (HN). The plasma dynamics in the ejecta explains the ultrarelativistic prompt emission in the MeV domain and the mildly-relativistic flares of the early afterglow in the X-ray domain. The feedback of the $\nu$NS emission on the HN explains the X-ray late afterglow and its power-law regime. All the above is in contrast with GRB models attempting to explain all the GRB phases with the kinetic energy of anultrarelativistic jet, as traditionally proposed in the "collapsar-fireball" model. In addition, BdHNe in their different flavors lead to $\nu$NS-NS or $\nu$NS-BH binaries. These binaries merge by gravitational wave emission producing short GRBs, establishing a connection between long and short GRBs and their occurrence rates.

[37]  arXiv:1905.06056 [pdf, ps, other]  Coffee Cup
Title: Thermal properties of slowly rotating asteroids: Results from a targeted survey
Comments: Accepted for publication in Astronomy & Astrophysics
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

Context. Earlier work suggests that slowly rotating asteroids should have higher thermal inertias than faster rotators because the heat wave penetrates deeper into the sub-surface. However, thermal inertias have been determined mainly for fast rotators due to selection effects in the available photometry used to obtain shape models required for thermophysical modelling (TPM).
Aims. Our aims are to mitigate these selection effects by producing shape models of slow rotators, to scale them and compute their thermal inertia with TPM, and to verify whether thermal inertia increases with the rotation period.
Methods. To decrease the bias against slow rotators, we conducted a photometric observing campaign of main-belt asteroids with periods longer than 12 hours, from multiple stations worldwide, adding in some cases data from WISE and Kepler space telescopes. For spin and shape reconstruction we used the lightcurve inversion method, and to derive thermal inertias we applied a thermophysical model to fit available infrared data from IRAS, AKARI, and WISE.
Results. We present new models of 11 slow rotators that provide a good fit to the thermal data. In two cases, the TPM analysis showed a clear preference for one of the two possible mirror solutions. We derived the diameters and albedos of our targets in addition to their thermal inertias, which ranged between 3$^{+33}_{-3}$ and 45$^{+60}_{-30}$ Jm$^{-2}$s$^{-1/2}$K$^{-1}$.
Conclusions. Together with our previous work, we have analysed 16 slow rotators from our dense survey with sizes between 30 and 150 km. The current sample thermal inertias vary widely, which does not confirm the earlier suggestion that slower rotators have higher thermal inertias.

[38]  arXiv:1905.06057 [pdf, other]  Coffee Cup
Title: Background-subtracted Solar Activity Maps
Comments: accepted for publication in Solar Physics (19 pages, 10 figures, 2 tables)
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

We introduce the concept of a Background-subtracted Solar Activity Map (BaSAM) as a new quantitative tool to assess and visualize the temporal variation of the photospheric magnetic field and the UV 160 nm intensity. The method utilizes data of the Solar Dynamics Observatory (SDO) and is applicable to both full-disk observations and regions-of-interest. We illustrate and discuss the potential of BaSAM resorting to datasets representing solar minimum and maximum conditions: (1) Contributions of quiet-Sun magnetic fields, i.e. the network and (decaying) plage, to solar activity can be better determined when their variation is measured with respect to the background given by "deep" magnetograms. (2) Flaring and intermittent brightenings are easily appraised in BaSAMs of the UV intensity. (3) Both magnetic-field and intensity variations demonstrated that the flux system of sunspots is well connected to the surrounding supergranular cells. In addition, producing daily full-disk BaSAMs for the entire mission time of SDO provides a unique tool to analyze solar cycle variations, showing how vigorous or frail are the variations of magnetic-field and intensity features.

[39]  arXiv:1905.06066 [pdf, other]  Coffee Cup
Title: Revisiting the wave optics effect on primordial black hole constraints from optical microlensing search
Comments: 10 pages, 7 figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

Microlensing of stars, e.g. in the Galactic bulge and Andromeda galaxy (M31), is among the most robust, powerful method to constrain primordial black holes (PBHs) that are a viable candidate of dark matter. If PBHs are in the mass range $M_{\rm PBH} \lower.5ex\hbox{$\; \buildrel > \over \sim \;$} 10^{-10}M_\odot$, its Schwarzschild radius ($r_{\rm Sch}$) becomes comparable with or shorter than optical wavelength ($\lambda)$ used in a microlensing search, and in this regime the wave optics effect on microlensing needs to be taken into account. For a lensing PBH with mass satisfying $r_{\rm Sch}\sim \lambda$, it causes a characteristic oscillatory feature in the microlensing light curve, and it will gives a smoking gun evidence of PBH if detected, because any astrophysical object cannot have such a tiny Schwarzshild radius. Even in a statistical study, e.g. constraining the abundance of PBHs from a systematic search of microlensing events for a sample of many source stars, the wave effect needs to be taken into account. We examined the impact of wave effect on the PBH constraints obtained from the $r$-band (6210\AA) monitoring observation of M31 stars in Niikura et al. (2019), and found that a finite source size effect is dominant over the wave effect for PBHs in the mass range $M_{\rm PBH}\simeq[10^{-11},10^{-10}]M_\odot$. We also discuss that, if a denser-cadence (10~sec), $g$-band monitoring observation for a sample of white dwarfs over a year timescale is available, it would allow one to explore the wave optics effect on microlensing light curve, if it occurs, or improve the PBH constraints in $M_{\rm PBH}\lower.5ex\hbox{$\; \buildrel > \over \sim \;$} 10^{-11}M_\odot$ even from a null detection.

[40]  arXiv:1905.06070 [pdf, other]  Coffee Cup
Title: Star-planet tidal interaction and the limits of gyrochronology
Comments: 12 pages, 7 figures, accepted for publication in A&A
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

Age estimation techniques such as gyrochronology and magnetochronology can't be applied to stars that exchanged angular momentum with their close environment. This is especially true for massive close-in planetary companion (with a periods of few days or less), which could have been strongly impacted the rotational evolution of the host star, along the stellar evolution, through the star-planet tidal interaction.
We showed that the interaction of a close-in massive planet with its host star can strongly modify the surface rotation rate of this latter, in most of the cases associated to a planetary engulfment. In such cases, a gyrochronology analysis of the star would wrongly make it appear as "rejuvenated", thus preventing us to use this method with confidence. To try overcome this issue, we eventually proposed the proof of concept of a new age determination technique that we call the tidal-chronology, which is based on the observed couple $\rm P_{rot,\star}$-$\rm P_{orb}$ of a given star-planet system.
The gyrochronology technique can only be applied to isolated star or star-planet systems outside a specific range of $\rm P_{rot,\star}$-$\rm P_{orb}$. This region tends to expand for increasing stellar and planetary mass. In that forbidden region, or if any planetary engulfment is suspected, gyrochronology should be used with extreme caution while tidal-chronology could be considered. While this technique does not provide a precise age for the system yet, it is already an extension of gyrochronology and could be helpful to determine a more precise range of possible age for planetary system composed of a star between 0.3 and 1.2 $M_{\odot}$ and a planet more massive than 1 $\rm M_{jup}$ initially located at few hundredth au of the host star.

[41]  arXiv:1905.06082 [pdf, other]  Coffee Cup
Title: Modelling baryonic feedback for survey cosmology
Comments: 25 pages, 4 figures, a short review
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)

Observational cosmology in the next decade will rely on probes of the distribution of matter in the redshift range between $0<z<3$ to elucidate the nature of dark matter and dark energy. In this redshift range, galaxy formation is known to have a significant impact on observables such as two-point correlations of galaxy shapes and positions, altering their amplitude and scale dependence beyond the expected statistical uncertainty of upcoming experiments at separations under 10 Mpc. Successful extraction of information in such a regime thus requires, at the very least, unbiased models for the impact of galaxy formation on the matter distribution, and can benefit from complementary observational priors. This work reviews the current state of the art in the modelling of baryons for cosmology, from numerical methods to approximate analytical prescriptions, and makes recommendations for studies in the next decade, including a discussion of potential probe combinations that can help constrain the role of baryons in cosmological studies. We focus, in particular, on the modelling of the matter power spectrum, $P(k,z)$, as a function of scale and redshift, and of the observables derived from this quantity. This work is the result of a workshop held at the University of Oxford in November of 2018.

[42]  arXiv:1905.06086 [pdf, other]  Coffee Cup
Title: An Analytical Solution to the Coalescence Time of Compact Binary Systems
Comments: 4 pages, 1 figure
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)

Compact binary systems coalesce over time due to radiation of gravitational waves, following the field equations of general relativity. Conservation of energy and angular momentum gives a mathematical description for the evolution of separation between the orbiting objects and eccentricity of the orbit. We develop an analytical solution to the coalescence time for any binary system with arbitrary separation between the compact objects and eccentricity of the orbit. This result is compared with the accurate numerical calculation and is applied to a number of known compact binary systems in the Galaxy.

[43]  arXiv:1905.06095 [pdf, ps, other]  Coffee Cup
Title: Mechanisms of astrophysical jet formation, and comparison with laboratory experiments
Comments: 18 pages, 17 figures, PoS (FRAPWS2018) 061
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

Jets are observed in young stellar objects, X-ray sources, active galactic nuclei (AGN). The mechanisms of jet formation may be divided in regular, acting continuously for a long time, and explosive ones. Continuous mechanisms are related with electrodynamics and radiation pressure acceleration, hydrodynamical acceleration in the nozzle inside a thick disk, acceleration by relativistic beam of particles. Explosive jet formation is connected with supernovae, gamma ray bursts and explosive events in galactic nuclei. Mechanisms of jet collimation may be connected with magnetic confinement, or a pressure of external gas. Explosive formation of jets in the laboratory is modeled in the experiments with powerful laser beam, and plasma focus.

[44]  arXiv:1905.06126 [pdf, ps, other]  Coffee Cup
Title: The role of small telescopes as a ground-based support for exoplanetary space missions
Comments: accepted for publication in CAOSP
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)

Small telescopes equiped with modern instrumentation are gaining on importance, especially, in the era of exoplanetary space missions such as TESS, PLATO and ARIEL. Crucial part of every planet hunting mission is now a ground-based follow-up of detectd planetary candidates. Mid-sized telescopes with apertures of 2 to 4-m with an existing instrumentation become more and more valued due to increasing need for observing time. In this paper, a brief overview on the follow-up process for exoplanetary space missions will be given. Requirements for the ground-based follow-up instrumentation will be discussed. Some of existing 2-m class telescope facilities and their capability and potential for the follow-up process of exoplanetary candidates will be presented. A special focus will be put on existing 2-m class telescopes in central Europe.

[45]  arXiv:1905.06161 [pdf, other]  Coffee Cup
Title: Hunting for open clusters in \textit{Gaia} DR2: the Galactic anticentre
Comments: 8 pages, accepted by Astronomy and Astrophysics (A&A) the 14th May, 2019
Subjects: Astrophysics of Galaxies (astro-ph.GA)

The Gaia Data Release 2 (DR2) provided an unprecedented volume of precise astrometric and excellent photometric data. In terms of data mining the Gaia catalogue, machine learning methods have shown to be a powerful tool to, for instance, search for hitherto unknown stellar structures. Particularly, supervised and unsupervised learning methods combined together allow to significantly improve the detection of open clusters. We systematically scan Gaia DR2 in a region covering the Galactic anticentre and the Perseus arm (120<=l<=205 and -10<=b<=10), with the goal of populating this region with open clusters and fine tuning the methodology, proposed in arXiv:1805.03045v2 and successfully applied to TGAS data, adapting it to different density regions. Our methodology uses an unsupervised, density based, clustering algorithm, DBSCAN, that identifies over-densities in the five dimensional astrometric parameter space (l,b,\varpi,\mu_{\alpha^*},\mu_{\delta}) that may correspond to physical clusters. The over-densities are separated into physical clusters (open clusters) or random statistical clusters using an artificial neural network to recognise the isochrone pattern that open clusters show in a colour magnitude diagram. The method is able to recover more than 75% of the open clusters confirmed in the search area. Moreover, we are able to detect 58 open clusters unknown previous to Gaia DR2, which represent an increase of around 25% with respect to the already catalogued ones in this region. We find that the census of nearby open clusters is not complete. Different machine learning based methodologies for a blind search of open clusters are complementary to each other, with no single method being able to detect the 100% of the existing groups. Our methodology has shown to be a reliable tool for the automatic detection of open clusters, designed to be applied to the full Gaia DR2 catalogue.

[46]  arXiv:1905.06165 [pdf, other]  Coffee Cup  Coffee Cup
Title: New Approach for Determination of Stellar Nucleosynthesis Abundances
Comments: 4 pages, 3 figures
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex)

The recent observation of neutron stars merger by the LIGO collaboration and the measurements of the event's electromagnetic spectrum as a function of time for different wavelengths, have altered profoundly our understanding of the $r$-process site, as well as considerably energized nuclear astrophysics research efforts. $R$-process abundances are a key element in $r$-process simulations, as a successful calculation must account for these abundances in the final debris of a stellar cataclysmic event. In this letter, mankind's complete knowledge of neutron cross sections obtained in the last 80 years, as encapsulated in the latest release of the Evaluated Nuclear Data File (ENDF/B) library, is used to obtain solar $r$-process abundances in a novel way. ENDF/B cross sections has been successfully used for decades in nuclear power and defense applications and are now used to obtain $r$-process abundances in a fully traceable, documented and unbiased way.

[47]  arXiv:1905.06240 [pdf, ps, other]  Coffee Cup
Title: Diffusion-limited Relic Particle Production
Comments: 10 pages, 3 figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)

We examine the thermal evolution of particle number densities in the early universe when the particles have a finite diffusion length. Assuming that annihilations are impossible when the mean separation of the particles is larger than their diffusion length, we derive a version of the Boltzmann equation for freeze out in this scenario and an approximate solution, accurate to better than 2\%. The effect of a finite diffusion length is to increase the final relic freeze-out abundance over its corresponding value when diffusion effects are ignored. When diffusion is limited only by scattering off of the thermal background, and the annihilation cross section is bounded by unitarity, a significant effect on the freeze-out abundance requires a scattering cross section much larger than the annihilation cross section. A similar effect is demonstrated when the relic particles are produced via the freeze-in mechanism, but in this case the finite diffusion length is due to the scattering of particles that annihilate into the relic particle of interest. For freeze in, the effect of a finite diffusion length is to reduce the final relic particle abundance. The effects of a finite diffusion length are most important when the scattering cross section or the relic mass are very large. While we have not found a particularly compelling example where this would affect previous results, with the current interest in new dark matter candidates it could become an important consideration.

[48]  arXiv:1905.06245 [pdf, other]  Coffee Cup
Title: Depth of maximum of air-shower profiles: testing the compatibility of measurements performed at the Pierre Auger Observatory and the Telescope Array experiment
Authors: Alexey Yushkov, Jose Bellido, John Belz, Vitor de Souza, William Hanlon, Daisuke Ikeda, Pierre Sokolsky, Yoshiki Tsunesada, Michael Unger (for the Pierre Auger and Telescope Array Collaborations)
Comments: 7 pages, 9 figures, presented at the UHECR 2018 (Paris, October 2018)
Journal-ref: forthcoming EPJ Web of Conferences (2019)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

At the Pierre Auger Observatory and the Telescope Array, the measurements of depths of maximum of air-shower profiles, $X_\mathrm{max}$, are performed using direct observations of the longitudinal development of showers with the help of the fluorescence telescopes. Though the same detection technique is used at both installations, the straightforward comparison of the characteristics of the measured $X_\mathrm{max}$ distributions is not possible due to the different approaches to the analysis of the recorded events. In this work, the Auger-Telescope Array composition working group presents a technique to compare the $X_\mathrm{max}$ measurements from the Auger Observatory and the Telescope Array. Applying this technique the compatibility of the first two moments of the measured $X_\mathrm{max}$ distributions is qualitatively tested for energies $10^{18.2}~{\rm eV} < E < 10^{19.0}~{\rm eV}$ using the recently published Telescope Array data from the Black Rock Mesa and Long Ridge fluorescence detector stations. For a quantitative comparison, simulations of air showers with EPOS-LHC, folded with effects of the Telescope Array detector, are required along with the inclusion in the analysis of the systematic uncertainties in the measurements of $X_\mathrm{max}$ and the energies of the events.

[49]  arXiv:1905.06251 [pdf, other]  Coffee Cup
Title: Measurements and tests of hadronic interactions at ultra-high energies with the Pierre Auger Observatory
Authors: Lorenzo Cazon (for the Pierre Auger Collaboration)
Comments: Ultra High Energy Cosmic Rays 2018 (UHECR2018)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Experiment (hep-ex)

Extensive air showers are complex objects, resulting of billions of particle reactions initiated by single cosmic ray at ultra-high-energy. Their characteristics are sensitive both to the mass of the primary cosmic ray and to the details of hadronic interactions. Many of the interactions that determine the shower features occur in kinematic regions and at energies beyond those tested by human-made accelerators. We will report on the measurement of the proton-air cross section for particle production at a center-of-mass energy per nucleon of 39 TeV and 56 TeV. We will also show comparisons of post-LHC hadronic interaction models with shower data by studying the moments of the distribution of the depth of the electromagnetic maximum, the number and production depth of muons in air showers, and finally a parameter based on the rise-time of the surface detector signal, sensitive to the electromagnetic and muonic component of the shower. While there is good agreement found for observables based on the electromagnetic shower component, discrepancies are observed for muon-sensitive quantities.

[50]  arXiv:1905.06260 [pdf, ps, other]  Coffee Cup
Title: The Shape Dependence of Vainshtein Screening in the Cosmic Matter Bispectrum
Comments: 26 pages, 7 figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

One of the most pressing questions in modified gravity is how deviations from general relativity can manifest in upcoming galaxy surveys. This is especially relevant for theories exhibiting Vainshtein screening, where such deviations are efficiently suppressed within a (typically large) Vainshtein radius. However, Vainshtein screening is known to be shape dependent: it is most effective around spherical sources, weaker around cylindrical objects and completely absent for planar sources. The Cosmic Web therefore offers a testing ground, as it displays many shapes in the form of clusters, filaments and walls.
In this work, we explicitly derive the signature of the shape dependence of Vainshtein screening on the matter bispectrum, by considering a cubic Galileon model with a conformal coupling to matter and a cosmological constant. We perform a second order perturbative analysis, deriving analytic, integral expressions for the bispectrum, which we integrate using \texttt{hi\_class}. We find that the shape dependence of Vainshtein screening enters the bispectrum with a unique scale-factor dependence of $\propto a^{3/2}$. The magnitude of the effect today is up to 2 % for a model whose linear growth rate deviates up to 5 % from $\Lambda$CDM.

[51]  arXiv:1905.06266 [pdf, other]  Coffee Cup
Title: Dust Polarization in Four Protoplanetary Disks at 3 mm: Further Evidence of Multiple Origins
Comments: 10 pages, 5 figures
Journal-ref: ApJL 877 (2019) L2
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

We present polarimetric observations of four Class II protoplanetary disks (DG Tau, Haro 6-13, RY Tau, and MWC 480) taken with the Atacama Large Millimeter/submillimeter Array (ALMA) at 3 mm. The polarization morphologies observed fall into two distinct categories: azimuthal polarization (DG Tau and Haro 6-13) and polarization parallel to the disk minor axis (RY Tau and MWC 480). The mechanisms responsible for disk polarization at millimeter and submillimeter wavelengths are currently under debate. In this Letter, we investigate two mechanisms capable of producing polarized dust emission in disks: self-scattering and grain alignment to the radiation anisotropy. The polarization morphologies of DG Tau and Haro 6-13 are broadly consistent with that expected from radiation alignment (though radiative alignment still does not account for all of the features seen in these disks), while RY Tau and MWC 480 are more consistent with self-scattering. Such a variation in the polarized morphology may provide evidence of dust grain size differences between the sources.

[52]  arXiv:1905.06283 [pdf, ps, other]  Coffee Cup
Title: Power-spectrum simulations of radial redshift distributions
Comments: 13 pages, 5 figures, accepted for publication in Astrophysics and Space Science
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

On the base of the simplest model of a modulation of 3D Gaussian field in $k$-space we produce a set of simulations to bring out the effects of a modulating function $f_{\rm mod} (k)=f_1 (k) + f_2 (k)$ on power spectra of radial (shell-like) distributions of cosmological objects, where a model function $f_1 (k)$ reproduces the smoothed power spectrum of underlying 3D density fluctuations, while $f_2 (k)$ is a wiggling function imitating the baryon acoustic oscillations (BAO). It is shown that some excess of realizations of simulated radial distributions actually displays quasi-periodical components with periods about a characteristic scale $2\pi/k \sim 100~h^{-1}$~Mpc detected as power-spectrum peaks in vicinity of the first maximum of the modulation function $f_2 (k)$. We revised our previous estimations of the significance of such peaks and found that they were largely overestimated. Thereby quasi-periodical components appearing in some radial distributions of matter are likely to be stochastic (rather than determinative), while the amplitudes of the respective spectral peaks can be quite noticeable. They are partly enhanced by smooth part of the modulating function $f_1(k)$ and, to a far lesser extent, by effects of the BAO (i.e. $f_2(k)$). The results of the simulations match quite well with statistical properties of the radial distributions of the brightest cluster galaxies (BCGs).

[53]  arXiv:1905.06288 [pdf, ps, other]  Coffee Cup
Title: A near-infrared study of the multi-phase outflow in the type-2 quasar J1509+0434
Comments: 6 pages, 4 figures, accepted for publication in MNRAS Letters
Subjects: Astrophysics of Galaxies (astro-ph.GA)

Based on new near-infrared spectroscopic data from the instrument EMIR on the 10.4 m Gran Telescopio Canarias (GTC) we report the presence of an ionized and warm molecular outflow in the luminous type-2 quasar J150904.22+043441.8 (z = 0.1118). The ionized outflow is faster than its molecular counterpart, although the outflow sizes that we derive for them are consistent within the errors (1.34$\pm$0.18 kpc and 1.46$\pm$0.20 kpc respectively). We use these radii, the broad emission-line luminosities and in the case of the ionized outflow, the density calculated from the trans-auroral [OII] and [SII] lines, to derive mass outflow rates and kinetic coupling efficiencies. Whilst the ionized and warm molecular outflows represent a small fraction of the AGN power ($\leq$0.033% and 0.0001% of L$_{bol}$ respectively), the total molecular outflow, whose mass is estimated from an assumed warm-to-cold gas mass ratio of 6$\times10^{-5}$, has a kinetic coupling efficiency of $\sim$1.7%L$_{bol}$. Despite the large uncertainty, this molecular outflow represents a significant fraction of L$_{bol}$ and it could potentially have a significant impact on the host galaxy. In addition, the quasar spectrum reveals bright and patchy narrow Pa$\alpha$ emission extending out to 4 arcsec (8 kpc) South-East and North-West from the active nucleus.

[54]  arXiv:1905.06300 [pdf, other]  Coffee Cup
Title: Stochastic inflation beyond slow roll
Comments: 20 pages without appendices (total 28 pages), 1 figure
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

We study the stochastic formalism of inflation beyond the usual slow-roll approximation. We verify that the assumptions on which the stochastic formalism relies still hold even far from the slow-roll attractor. This includes demonstrating the validity of the separate universe approach to evolving long-wavelength scalar field perturbations beyond slow roll. We also explain that, in general, there is a gauge correction to the amplitude of the stochastic noise. This is because the amplitude is usually calculated in the spatially-flat gauge, while the number of e-folds is used as the time variable (hence one works in the uniform-$N$ gauge) in the Langevin equations. We show that these corrections vanish in the slow-roll limit, but we also explain how to calculate them in general. We compute them in difference cases, including ultra-slow roll and the Starobinsky model that interpolates between slow roll and ultra-slow roll, and find the corrections to be negligible in practice. This confirms the validity of the stochastic formalism for studying quantum backreaction effects in the very early universe beyond slow roll.

Cross-lists for Thu, 16 May 19

[55]  arXiv:1905.03947 (cross-list from gr-qc) [pdf, ps, other]  Coffee Cup
Title: Love in Extrema Ratio
Comments: Essay selected for an Honorable Mention in the Gravity Research Foundation Essay Competition 2019. v2: two references added, version to appear in IJMPD
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE)

The tidal deformability of a self-gravitating object leaves an imprint on the gravitational-wave signal of an inspiral which is paramount to measure the internal structure of the binary components. We unveil here a surprisingly unnoticed effect: in the extreme-mass ratio limit the tidal Love number of the central object (i.e. the quadrupole moment induced by the tidal field of its companion) affects the gravitational waveform at the leading order in the mass ratio. This effect acts as a magnifying glass for the tidal deformability of supermassive objects but was so far neglected, probably because the tidal Love numbers of a black hole (the most natural candidate for a compact supermassive object) are identically zero. We argue that extreme-mass ratio inspirals detectable by the future LISA mission might place constraints on the tidal Love numbers of the central object which are roughly 8 orders of magnitude more stringent than current ones on neutron stars, potentially probing all models of black hole mimickers proposed so far.

[56]  arXiv:1905.05764 (cross-list from hep-th) [pdf, other]  Coffee Cup
Title: An Inflationary Probe of Cosmic Higgs Switching
Comments: 28 pages, 9 figures
Subjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)

A scalar Higgs field can be repeatedly switched on and off when it couples to a classically oscillating scalar modulus field. The modulus flips the Higgs mass term between stable and tachyonic values. We study a cosmological scenario in which such repeated phase transitions occur during inflation. An irrelevant operator coupling the Higgs field to the inflaton can then imprint the pattern of phase transitions in the correlation functions of the inflaton. Using both numerical and analytic studies, we show that the inflaton 2-point function carries characteristic imprints of the modulus oscillation and its effect on the Higgs boson. We briefly remark on the potential observability of such patterns and how they might be distinguished from other dynamics in the early universe.

[57]  arXiv:1905.05776 (cross-list from hep-ph) [pdf, other]  Coffee Cup
Title: Light Dark Matter from Inelastic Cosmic Ray Collisions
Comments: 5 pages, 4 figures
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE)

Direct detection experiments relying on nuclear recoil signatures lose sensitivity to sub-GeV dark matter for typical galactic velocities. This sensitivity is recovered if there exists another source of flux with higher momenta. Such an energetic flux of light dark matter could originate from the decay of mesons produced in inelastic cosmic ray collisions. We compute this novel production mechanism---a cosmic beam dump experiment---and estimate the resulting limits from XENON1T and LZ. We find that the dark matter flux from inelastic cosmic rays colliding with atmospheric nuclei can dominate over the flux from elastic collisions with relic dark matter. The limits that we obtain for hadrophilic scalar mediator models are competitive with those from MiniBoone for light MeV-scale mediator masses.

[58]  arXiv:1905.05811 (cross-list from nucl-ex) [pdf, other]  Coffee Cup
Title: Electromagnetic Backgrounds and Potassium-42 Activity in the DEAP-3600 Dark Matter Detector
Subjects: Nuclear Experiment (nucl-ex); Instrumentation and Methods for Astrophysics (astro-ph.IM)

The DEAP-3600 experiment is searching for WIMP dark matter with a 3.3 tonne single phase liquid argon (LAr) target, located 2.1 km underground at SNOLAB. The experimental signature of dark matter interactions is keV-scale $^{40}$Ar nuclear recoils (NR) producing 128 nm LAr scintillation photons observed by PMTs. The largest backgrounds in DEAP-3600 are electronic recoils (ER) induced by $\beta$ and $\gamma$-rays originating from internal and external radioactivity in the detector material. A background model of the ER interactions in DEAP-3600 was developed and is described in this work. The model is based on several components which are expected from radioisotopes in the LAr, from ex-situ material assay measurements, and from dedicated independent in-situ analyses. This prior information is used in a Bayesian fit of the ER components to a 247.2 d dataset to model the radioactivity in the surrounding detector materials.
While excellent discrimination between ERs and NRs is reached with pulse shape discrimination, utilizing the large difference between fast and slow components of LAr scintillation light, detailed knowledge of the ER background and activity of detector components, sets valuable constraints on other key types of backgrounds in the detector: neutrons and alphas.
In addition, the activity of $^{42}$Ar in LAr in DEAP-3600 is determined by measuring the daughter decay of $^{42}$K. This cosmogenically activated trace isotope is a relevant background at higher energies for other rare event searches using atmospheric argon e.g. DarkSide-20k, GERDA or LEGEND. The specific activity of $^{42}$Ar in the atmosphere is found to be $40.4 \pm 5.9$ $\mu$Bq/kg of argon.

[59]  arXiv:1905.06011 (cross-list from gr-qc) [pdf, other]  Coffee Cup
Title: Improving the NRTidal model for binary neutron star systems
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE)

Accurate and fast gravitational waveform (GW) models are essential to extract information about the properties of compact binary systems that generate GWs. Building on previous work, we present an extension of the NRTidal model for binary neutron star (BNS) waveforms. The upgrades are: (i) a new closed-form expression for the tidal contribution to the GW phase which includes further analytical knowledge and is calibrated to more accurate numerical relativity data than previously available; (ii) a tidal correction to the GW amplitude; (iii) an extension of the spin-sector incorporating equation-of-state-dependent finite size effects at quadrupolar and octupolar order; these appear in the spin-spin tail terms and cubic-in-spin terms, both at 3.5PN. We add the new description to the precessing binary black hole waveform model IMRPhenomPv2 to obtain a frequency-domain precessing binary neutron star model. In addition, we extend the SEOBNRv4_ROM and IMRPhenomD aligned-spin binary black hole waveform models with the improved tidal phase corrections. Focusing on the new IMRPhenomPv2_NRTidalv2 approximant, we test the model by comparing with numerical relativity waveforms as well as hybrid waveforms combining tidal effective-one-body and numerical relativity data. We also check consistency against a tidal effective-one-body model across large regions of the BNS parameter space.

[60]  arXiv:1905.06108 (cross-list from hep-ph) [pdf, other]  Coffee Cup
Title: Singlet-doublet/triplet dark matter and neutrino masses
Comments: 4 pages, 1 figure; contribution to the 2019 EW session of the 54th Rencontres de Moriond (summary of arXiv:1812.11133)
Subjects:  Coffee Cup High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

In these proceedings, we present a study of a combined singlet--doublet fermion and triplet scalar model for dark matter (DM). Together, these models form a simple extension of the Standard Model (SM) that can account for DM and explain the existence of neutrino masses, which are generated radiatively. However, this also implies the existence of lepton flavour violating (LFV) processes. In addition, this particular model allows for gauge coupling unification. The new fields are odd under a new $\mathbb{Z}_2$ symmetry to stabilise the DM candidate. We analyse the DM, neutrino mass and LFV aspects, exploring the viable parameter space of the model. This is done using a numerical random scan imposing successively the neutrino mass and mixing, relic density, Higgs mass, direct detection, collider and LFV constraints. We find that DM in this model is fermionic for masses below about 1 TeV and scalar above. We observe a high degree of complementarity between direct detection and LFV experiments, which should soon allow to fully probe the fermionic DM sector and at least partially the scalar DM sector.

[61]  arXiv:1905.06128 (cross-list from physics.space-ph) [pdf]  Coffee Cup
Title: First Results of Arar-Magnetometer Station in Saudi Arabia
Comments: 4 pages
Subjects: Space Physics (physics.space-ph); Solar and Stellar Astrophysics (astro-ph.SR); Geophysics (physics.geo-ph)

This paper presents the first results of a new Arar-magnetometer station located (Geographic Coordinates: 30 58.5 N, 41 2.3 E) at Northern Border University in Saudi Arabia. The geomagnetic response detected by the station during a moderate magnetic storm of April 20, 2018, is examined as an initial study. The total magnetic field components measured by the station showed a prompt increase in coincident with the Sudden Storm Commencement (SSC) time measured by ACE satellite. The high rate of magnetic field digital data system of Arar-Magnetometer station with a sampling rate of 0.1 s allowed us to study the geomagnetic pulsation at the northern region of the Arabian Peninsula for the first time.

[62]  arXiv:1905.06182 (cross-list from gr-qc) [pdf, other]  Coffee Cup
Title: Post-inflationary phases stiffer than radiation and Palatini formulation
Comments: 25 pages
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)

If the inflaton and the quintessence fields are identified, the background geometry evolves through a stiff epoch undershooting the expansion rate of a radiation-dominated plasma. For some classes of inflationary potentials this scenario is at odds with the current observational evidence since the corresponding tensor-to-scalar ratio is too large. Quintessential inflation is analyzed when the gravitational action is supplemented by a contribution quadratic in the Einstein-Hilbert term. In the Palatini formulation the addition such a term does not affect the scalar modes during the inflationary phase and throughout the course of the subsequent stiff epoch but it suppresses the tensor power spectrum and the tensor-to-scalar ratio. While in the Palatini formulation the power-law potentials leading to a quintessential inflationary dynamics are again viable, the high-frequency spike of the relic graviton spectrum is squeezed and the whole signal is suppressed at least when the higher-order contributions appearing in the action are explicitly decoupled from the inflaton.

[63]  arXiv:1905.06328 (cross-list from physics.ins-det) [pdf, other]  Coffee Cup
Title: Position sensitive resonant Schottky cavities for heavy ion storage rings
Comments: EMIS 2018 conference proceedings, 4 pages, 7 pictures
Subjects: Instrumentation and Detectors (physics.ins-det); Instrumentation and Methods for Astrophysics (astro-ph.IM); Nuclear Experiment (nucl-ex); Accelerator Physics (physics.acc-ph)

Studying the rapid neutron capture process (r-process) in stellar environments, that leads to the creation of elements heavier than 56-Fe, remains one of the fundamental questions of modern physics and therefore an active field of research within nuclear astrophysics. Exotic nuclides which participate in the r-process due to their low production yield and short half-life can be efficiently investigated in storage rings. In such facilities non-destructive methods of particle detection are often used for in-flight measurements based on frequency analysis. Due to the low signal level the detectors should be very sensitive and fast because of short lifetime of the particles. Resonant Schottky cavity pickups fulfill such requirement. Apart from their applications in the measurements of beam parameters, they can be used in non-destructive in-ring decay studies of radioactive ion beams. In addition, position sensitive Schottky pick-up cavities can enhance precision in the isochronous mass measurement technique. The goal of this work is to design such a position sensitive resonant Schottky cavity pickup based on theoretical calculations and simulations.

Replacements for Thu, 16 May 19

[64]  arXiv:1806.04668 (replaced) [pdf, other]  Coffee Cup
Title: The Universe at extreme magnification
Authors: Jose M. Diego
Comments: 22 pages and 11 figures. Matches accepted versiion in A&A
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[65]  arXiv:1808.10465 (replaced) [pdf, other]  Coffee Cup
Title: Global analyses of Higgs portal singlet dark matter models using GAMBIT
Comments: 30 pages, 12 figures. v2 matches the published version
Journal-ref: Eur.Phys.J. C79 (2019) no.1, 38
Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[66]  arXiv:1809.06380 (replaced) [pdf, other]  Coffee Cup
Title: A Closer look at Bursty Star Formation with $L_{Hα}$ and $L_{UV}$ Distributions
Comments: 19 pages, 11 figures, Accepted to ApJ
Subjects: Astrophysics of Galaxies (astro-ph.GA)
[67]  arXiv:1809.10223 (replaced) [pdf, other]  Coffee Cup
[68]  arXiv:1810.06895 (replaced) [pdf, other]  Coffee Cup
Title: STIM map: detection map for exoplanets imaging beyond asymptotic Gaussian residual speckle noise
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
[69]  arXiv:1810.07055 (replaced) [pdf, other]  Coffee Cup
Title: The optimal gravitational softening length for cosmological N-body simulations
Comments: 7 pages, 4 figures, version accepted by MNRAS
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
[70]  arXiv:1811.07917 (replaced) [pdf, other]  Coffee Cup
Title: Anisotropic stars as ultracompact objects in General Relativity
Comments: 7+2 pages, 6 figures; v2: include extra material (general covariant framework for anisotropic fluids in General Relativity without symmetries and code validation); to appear in PRD
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
[71]  arXiv:1811.09891 (replaced) [pdf]  Coffee Cup
Title: Jet propagation velocity and environment density of giant radio sources with steep radio spectrum
Comments: 15 pages, 9 figures (accepted for publication in Astrophysics and Space Science, manuscript number ASTR-D-18-00626R2)
Subjects: Astrophysics of Galaxies (astro-ph.GA)
[72]  arXiv:1811.11732 (replaced) [pdf, other]  Coffee Cup
[73]  arXiv:1812.07743 (replaced) [pdf, other]  Coffee Cup
Title: Evidence for shock-heated gas in the Taffy Galaxies and Bridge from Optical Emission-Line IFU spectroscopy
Comments: 19 pages, 13 figures. Accepted for publication in ApJ
Subjects: Astrophysics of Galaxies (astro-ph.GA)
[74]  arXiv:1812.08192 (replaced) [pdf, other]  Coffee Cup
Title: The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream
Comments: 17 pages, 11 figures. Updated to version accepted to MNRAS after minor revision
Subjects: Astrophysics of Galaxies (astro-ph.GA)
[75]  arXiv:1901.03096 (replaced) [pdf, other]  Coffee Cup
Title: Mass bias evolution in tSZ cluster cosmology
Comments: 14 pages, 9 figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[76]  arXiv:1901.04748 (replaced) [pdf, other]  Coffee Cup
Title: Statistical properties of substructures around Milky Way-sized haloes and their implications for the formation of stellar streams
Comments: Accepted for publication in MNRAS, 13 pages, 10 figures, 1 table
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[77]  arXiv:1901.05116 (replaced) [pdf, other]  Coffee Cup
Title: AutoRegressive Planet Search: Methodology
Comments: 40 pages, 12 figures, to appear in the Astronomical Journal
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
[78]  arXiv:1901.05971 (replaced) [pdf, other]  Coffee Cup
Title: Charting nearby dust clouds using Gaia data only
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
[79]  arXiv:1902.00459 (replaced) [pdf, other]  Coffee Cup
Title: Magnetogenesis from isocurvature initial conditions
Comments: 22 pages. Minor corrections. Matches version published in JCAP
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[80]  arXiv:1902.01749 (replaced) [pdf, other]  Coffee Cup
Title: rPICARD: A CASA-based Calibration Pipeline for VLBI Data. Calibration and imaging of 7 mm VLBA observations of the AGN jet in M87
Comments: Accepted for publication Astronomy and Astrophysics. Code available at this https URL
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Astrophysical Phenomena (astro-ph.HE)
[81]  arXiv:1902.02349 (replaced) [pdf, other]  Coffee Cup
Title: Transition of BH feeding from the quiescent regime into star-forming cold disk regime
Comments: 16 pages, 13 figures, published in MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
[82]  arXiv:1902.06639 (replaced) [pdf, ps, other]  Coffee Cup
Title: A gauge invariant prescription to avoid $γ$-crossing instability in Galileon bounce
Comments: 6 pages, 3 figures. Comments are welcome; v2: minor changes, published in Physical Review D
Journal-ref: Phys. Rev. D 99, 103517 (2019)
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
[83]  arXiv:1903.05620 (replaced) [pdf, other]  Coffee Cup
Title: Period spacings of gravity modes in rapidly rotating magnetic stars I. Axisymmetric fossil field with poloidal and toroidal components
Comments: 9 pages, 5 figures, 1 table, accepted in A&A
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
[84]  arXiv:1903.09163 (replaced) [pdf, other]  Coffee Cup
Title: Stellar content, planetary nebulae, and globular clusters of [KKS2000]04 (NGC1052-DF2)
Comments: 10 pages, 4 figures, accepted for publication in MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA)
[85]  arXiv:1903.09782 (replaced) [pdf, other]  Coffee Cup
Title: XSPEC model for testing the Kerr black hole hypothesis using the continuum-fitting method
Comments: 9 pages, 4 figures. v2: refereed version
Journal-ref: Phys. Rev. D 99, 104031 (2019)
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE)
[86]  arXiv:1904.02726 (replaced) [pdf, other]  Coffee Cup
Title: Identifying Exoplanets with Deep Learning III: Automated Triage and Vetting of TESS Candidates
Comments: 15 pages, 6 figures, 2 tables, accepted for publication in AJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
[87]  arXiv:1904.05127 (replaced) [pdf, ps, other]  Coffee Cup
Title: Tentative evidence of spatially extended GeV emission from SS433/W50
Comments: 7 pages, 4 figures, accepted for publication in A&A
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
[88]  arXiv:1904.08887 (replaced) [pdf, ps, other]  Coffee Cup
Title: The accelerating rotation of the magnetic He-weak star HD 142990
Comments: 10 pages, 6 figures, 3 tables, accepted for publication in MNRAS
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
[89]  arXiv:1904.12312 (replaced) [pdf, other]  Coffee Cup
Title: Bouncing Universe from Nothing
Comments: 9 pages, 4 figures; version submitted to a journal, references replaced and added
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
[90]  arXiv:1905.03080 (replaced) [pdf, other]  Coffee Cup
Title: Polarization studies of Rotating Radio Transients
Comments: Submitted to MNRAS, 10 pages, 6 figures
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
[91]  arXiv:1905.04475 (replaced) [pdf, other]  Coffee Cup
Title: An Ejecta Kinematics Study of Kepler's Supernova Remnant with High-Resolution $Chandra$ HETG Spectroscopy
Comments: Submitted to ApJ. 14 pages, 6 figures, and 2 tables
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
[92]  arXiv:1905.04670 (replaced) [pdf, ps, other]  Coffee Cup
Title: A Pulsar Wind Nebula Embedded in the Kilonova AT2017gfo Associated with GW 170817/GRB 170817A
Comments: 16 pages, 7 figures and 1 table
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
[93]  arXiv:1905.05093 (replaced) [pdf]  Coffee Cup
Title: Impact of Space Weather on Climate and Habitability of Terrestrial Type Exoplanets
Comments: 206 pages, 24 figures, 1 table; Review paper. International Journal of Astrobiology (2019)
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
[94]  arXiv:1905.05719 (replaced) [pdf]  Coffee Cup
Title: Kepler-62f: Kepler's First Small Planet in the Habitable Zone, but Is It Real?
Comments: Published in New Astronomy Reviews special issue on key Kepler discoveries. Published version available here: this https URL
Journal-ref: New Astronomy Reviews, Volume 83, November 2018, Pages 28-36
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

[ total of 94 entries: 1-94 ]
[ showing up to 2000 entries per page: fewer | more ]


Disable MathJax (What is MathJax?)

Links to: arXiv, form interface, find, astro-ph, recent, 1905, contact, help  (Access key information)