Gillian Wilson's Homepage |
Welcome to Gillian's homepage! I am an associate professor in the Department of Physics & Astronomy at the University of California, Riverside .
Previously I was on staff at the Spitzer Science Center, which is affiliated with the Infrared Processing and Analysis Center IPAC, the Jet Propulsion Laboratory JPL, and the California Institute of Technology.
1) Very High Redshift ( 1 < z < 2 ) Clusters of Galaxies:
Because clusters are very rare, maximizing the volume surveyed is important to detect a representative sample. This survey finds clusters by looking for overdensities of red, elliptical galaxies (the red-sequence technique). Its innovation is that it utilizes Spitzer IRAC IR data, allowing clusters to be detected to higher redshift than traditional techniques. SpARCS is currently the widest-area survey for 1 < z < 2 clusters.
2) Field Galaxy Evolution Studies:
Extremely Red Objects The nature of EROs has been an intriguing mystery for the last couple of decades. In this paper, we showed that is is possible to classify them into early-type, dusty starburst or power-law (AGN) galaxies, using their mid-IR colors
Galaxy Clustering Evolution is a function of apparent magnitude, color and morphological type, and is closely related to the growth of galaxy dark matter halos and black holes. To my knowledge, this paper was the first attempt to study the redshift evolution of clustering of a population of galaxies of the same morphological type and absolute luminosity.
Star Formation History Inferring the evolution in star formation from various methods e.g., in this case, the rest-frame UV.
3) Mapping Dark Matter using Weak Gravitational Lensing
Any foreground mass (the lens) will bend the path of light rays coming from a more distant galaxy (the source). If the lens is very massive or dense (e.g., a cluster of galaxies or a quasar) and the source lies close to the line of sight through the center of the cluster, multiple or spectacularly distorted images of the source galaxy may appear to the observer. For obvious reasons, this is known as strong lensing.
More commonly, the source galaxy is only weakly lensed, distorted very slightly (<1% change in shape). However, analyzing the distortions from many weakly lensed galaxies collectively is a very powerful technique to directly infer the amount and distribution of matter in the universe, and to study the relation between galaxies and dark matter. Gravitational lensing can be used to make maps of dark matter and compare those to the distribution of galaxies, or to measure the dark matter in individual galaxy halos.
More details of some of the lensing projects I have been involved in over the years may be found here. Most notably, in 2000, my Hawaii colleagues and I (simultaneously with 3 other groups), made the very first measurement of "cosmic shear", directly measuring dark matter over large scales. By comparing the observed shear signal with numerical simulations, it is possible to place constraints on the mass density of the universe. From these measurements and those using other techniques, it appears there is insufficient mass in the universe for it ever to recollapse in a "Big Crunch".
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Department of Physics & Astronomy
University of California, Riverside 3401 Watkins Drive Riverside, CA 92521 |
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Tel: (951) 827 6274 |
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gillianw@ucr.edu |
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Fax: (951) 827 4529 |
