Neutrino Astrophysics (Prof. Francis Halzen, Prof. Albrecht Karle, Prof. Reina Maruyama and Prof. Stefan Westerhoff):
Having taken data for the last two years, the completed IceCube neutrino detector at the South Pole is the first instrument with the sensitivity required to capture signals of cosmic neutrinos. Rather than collecting light, it probes the high-energy Universe by detecting neutrinos. Since the 1950s, scientists have built a compelling case for using high-energy neutrinos as ideal messengers from the most interesting, violent, and least understood phenomena in the Universe.
Throughout the last decade, an international collaboration of scientists has designed, constructed, and operated the first kilometer-scale neutrino telescope. Originally conceived at the University of Wisconsin, IceCube has transformed a cubic kilometer of natural Antarctic ice into a Cherenkov detector. Optical sensors embedded in the ice detect the photons radiated by charged particles produced in neutrino interactions. They detect the faint flashes of light created by neutrino interactions in the transparent ice.
Since early construction of the detector, the IceCube group has employed about 5 to 10 undergraduates. Tasks have ranged from hardware (development of optical sensors), to software (e.g., for data acquisition), to data analysis (measuring atmospheric neutrino fluxes at TeV-energy and searching the large neutrino samples collected for gamma-ray bursts or other potential cosmic accelerators emitting neutrinos). Several undergraduates have visited the South Pole to perform hardware tasks that they had previously familiarized themselves with in the laboratory. Unfortunately, this will not be feasible during Madison's summer months.
Observational Cosmology (Prof. Peter Timbie):
The Observational Cosmology group uses two astrophysical tools to study the evolution and structure of the universe: 1) the ancient photons that make up the 2.7 K cosmic microwave background (CMB) allow us to explore cosmological history as far back as a redshift of z = 1400, some 300,000 years after the Big Bang; 2) radiation from neutral hydrogen gas at a wavelength of 21-cm traces the large scale distribution of matter and dark matter, which in turn probes dark energy, neutrino mass, etc.
Students in the Observational Cosmology group assist in building the most sensitive detectors of microwave and radio radiation possible and can learn about radio astronomy, cryogenics, superconductivity, microwave circuits and antennas, and data analysis.
REU students can choose to work on the development of a superconducting microwave sensor called a microwave kinetic inductance detector (MKID), specifically designed for measurements of the polarization of the CMB. CMB polarization is expected to arise from gravitational waves released during the inflation process during the Big Bang. Another project is to design and test antennas and receivers for the Hydrogen Structure Array, a radio interferometer under development for measuring 21-cm radiation.
Observational Stellar Astrophysics (Prof. Bob Mathieu):
Angular momentum is central to almost all facets of stellar astrophysics. The Wisconsin Stellar Angular Momentum group is using the WIYN telescopes to study angular momentum evolution in several contexts.
As part of the NSF-supported WIYN Open Cluster Study, we are defining both stellar rotation period distributions and binary populations in open clusters. These data will permit the first large-scale studies of the interplay of orbital and rotational angular momentum in solar-type stars. We are also exploring rotation period distributions among pre-main-sequence stars in order to test the recent theories of coupling between stellar magnetic fields and protostellar disks. Finally, we have underway a major study of pre-main-sequence eclipsing binaries, with the ultimate goal of precisely measuring stellar masses and thereby calibrating modern pre-main-sequence stellar evolution tracks.
Depending upon the particular interests of students, possible projects could involve spectroscopic measurement of precise stellar radial velocities using the multi-object spectrograph of WIYN, reductions of CCD time-series data to light curves, techniques for modeling eclipsing binary light curves, or Monte Carlo modeling of stellar rotation evolution. An observing run at the WIYN Observatory would be likely.
Title: Towards a Better Understanding of our Nearest Extragalactic Neighbors (Prof. Eric Wilcots)
One of the little-appreciated facts about the Magellanic Clouds, the nearest extragalactic neighbors to the Milky Way, is that they are simply the closest examples of a morphological class of galaxy that is well represented in the local Universe. The recent implication that the Clouds could be making their first passage by the Milky Way has weakened the notion that the characteristic structure of the Large Magellanic Cloud - a single spiral arm and a luminous stellar bar possibly offset from the center of the galaxy - is a result of its interaction with the Milky Way. Professor Wilcots has a number of research projects for REU students motivated by the idea that one way to better understand the LMC is to better understand the morphological class of Magellanic spirals in general. The various projects include:
analyzing new observations obtained with the WIYN 3.5m telescope to measure the stellar and ionized kinematics of Magellanic spirals to determine their mass distribution, their star formation history, and whether or not their bars are real;
analyzing new data from the Australia Telescope Compact Array radio telescope to map the distribution and kinematics of the neutral gas in Magellanic spirals;
analyzing archival and SDSS data to build a three-dimensional model of the large-scale environments of Magellanic spirals.
Galaxy Groups (Prof. Eric Wilcots)
The broad bimodal distribution of galaxies between a population of red, passively evolving galaxies and blue, star-forming ones is now well-established. There is also broad agreement that the transformation of galaxies from the so-called blue cloud to the red sequence is a result of removal or exhaustion of a galaxy’s supply of gas and the subsequent shutting down of its star formation. Meanwhile, modern simulations of the formation and growth of large-scale structure in the Universe show that galaxy clusters are the result of a hierarchical process by which individual galaxy groups merge. The bulk of current observations indicate that the transformation of galaxies is largely complete once they are well-established residents of large clusters. All of this suggests that the transformation of galaxies largely takes place outside of the central regions of clusters and, quite possibly, in the lower density environments of galaxy groups. This research project is targeted at understanding not only where galaxy transformation takes place, but also at understanding the relative importance of the different mechanisms by which a galaxy’s gas content is depleted. The REU student will be using archival and survey data to understand the evolution of galaxy groups; this could include applying a multiwavelength approach to correlate the star formation rate and population of active galactic nuclei within groups with their gas content and larger environment or using WIYN 3.5m and archival data to measure the dynamical growth of galaxy groups.
Galaxies and their environments (Prof. Jay Gallagher):
We are obtaining optical/infrared observations from a variety of ground-based telescopes, including the 3.5-m WIYN and the 4.2-m William Herschel Telescope, for a study of how the internal structures of galaxies are modified by their environments.
This project involves the quantitative analysis of galaxy images to define basic structures, the measurement of star formation rates, and determinations of internal stellar and ionized gas kinematics. We are applying these techniques to galaxies with special characteristics, such as those with signatures of recent disturbances, e.g., polar ring galaxies and starbursts, as well as to systems that appear to have been quiescent for long time periods (such as "super thin" disk galaxies).
This will provide an REU student with a range of opportunities for the collection, analysis, and interpretation of galaxy observations within the framework of dynamical constraints on their evolutionary processes.
X-ray astrophysics (Prof. Dan McCammon):
The last few years has seen a revolution in the spectroscopic and imaging sensitivity of astrophysical X-ray detectors. We have a very instrumentally-based program aimed at developing a new type of detector technology that measures the temperature rise produced by the absorption of single X-ray photons and can achieve energy resolutions 100 times better than a theoretically perfect CCD or solid state detector.
We are using these detectors in a sounding rocket program to study the galactic and extragalactic soft X-ray backgrounds. Improvements in the detectors will allow a search for the "missing baryons" in intergalactic space, and improved studies of the very hot components of the interstellar medium in our galaxy. We also support the deployment of similar detectors on general-purpose space-based observatories such as Astro-H. Interested students can learn fabrication and cryogenic techniques needed to assemble and test detectors, and methods of X-ray data analysis.
High Velocity Clouds (Dr. Bart Wakker):
Understanding the evolution of galaxies involves understanding how the gas is distributed and how it is accreted over time. Dr. Wakker works on many aspects of gas in the galactic halos, including hot gas, and high-velocity gas.
Possible summer projects involve determining distances to halo gas, measuring their composition, observing ionized gas, and also related aspects of the ISM in the Magellanic Clouds. Students working with Dr. Wakker will have access to a unique body of both ground and spaced based data.
Warm Ionized Medium (Dr. Matt Haffner):
Under the leadership of Prof. Ron Reynolds, Wisconsin has carried out the first survey of the entire galaxy in the H-alpha emission line of ionized hydrogen. These maps show the location and effect of hot ionizing stars, but also indicate the presence of a mysterious, low density ionized gas filling much of interstellar space. The velocity resolution provided by WHAM can allow astronomers to map out the distribution of this gas, while observing other diffuse optical emission lines can characterize the temperature, chemical state, and ionization level of the gas.
Star Formation in the Milky Way (Prof. Ed Churchwell, Dr. Barb Whitney):
Prof. Churchwell is leading a large scale survey, GLIMPSE (Galactic Legacy Infrared Midplane Survey Extraordinaire), to map the inner Galactic plane using the IRAC detector on the Space Infrared Telescope Facility.
This project has been granted over 800 hours of observing time to map out the inner Galaxy in wavelengths from 3.6 to 8.0 microns with unprecedented angular resolution and sensitivity. It will produce a complete census of star formation in the inner Milky Way and resolve some fundamental questions of stellar Galactic structure.
Interested students will search for interersting star formation regions and characterize the nature of star formation in the inner Galaxy.
Star Forming Regions and Polarization (Prof. Alex Lazarian):
Magnetohydrodynamic (MHD) turbulence is a critical component of the current paradigms of star formation, dynamo theory, particle transport, magnetic reconnection and evolution of the interstellar medium. In order to gain understanding of how MHD turbulence regulates processes in the Galaxy, a confluence of numerics, observations and theory must be employed. This project will deal with the development of new techniques for studies of MHD turbulence using a combination of numerics and observational data. It will be a good project for a student interested in data analysis programming, and working across both theory and observations.