Jul 25, 2014

Isak Wold, UW Madison

"An Observational Study of Quasar Host Galaxies, Radio Galaxies, and Lyman Alpha Emitters"

I develop and implement a method to provide stellar
age constraints for the host galaxies of nearby (z<0.3) quasars.  The
observational strategy is to observe spectroscopically quasar host galaxies
offset from the bright central point source to maximize the signal-to-noise of
the stellar light.  The central quasar is also spectroscopically observed, so
that any nuclear light scattered into the off-axis spectrum can be efficiently
modeled and subtracted. I test the reliability of this technique via a Monte-Carlo routine in which the correspondence between
synthetic spectra with known parameters and the model output is
determined. I apply this model to a preliminary sample of 10 objects, and I
compare my results to previous studies.
I present 1.4 GHz catalogs for the cluster fields
A370 and A2390 observed with the Very Large Array.  These are two of the deepest
radio images of cluster fields ever taken.  I construct differential number counts for each field and find
results consistent with previous studies. I emphasize the need to account for cosmic variance.  These high resolution, ultra-deep radio catalogs will be vital to future multiwavelength studies.
Finally, I apply a newly developed search method to all of the
deep GALEX grism fields, which correspond to some
of the most intensively studied regions in the sky. My work provides
the first large sample of z=0.67-1.16 LAEs (N=60) that can be used
to investigate the physical properties of these galaxies. I catalog the
candidate z=1 LAE samples in each field and give optical redshifts from
both archival and newly obtained observations. With X-ray, UV, and optical
data, I determine the false detection rate (cases where the emission line is
either not confirmed or is not Lya) and the AGN contamination rate of my
sample. With the remaining LAEs, I compute the LAE galaxy luminosity function
(LF) at z=1 and use this to investigate the evolution of the
Lya LF and the Lya escape fraction over the redshift range from z=0.3 to z=2. 

Event Details

Jul 25, 2014


4421 Sterling Hall

Thesis Defense

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