This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
Dr Zehavi will analyze and model the clustering of galaxies in large surveys such as the Sloan Digital Sky Survey (SDSS), to probe galaxy formation and the development of cosmic large-scale structure. She and others have shown that on small scales, dim red galaxies are more strongly clustered than brighter ones. This could be explained if the dim galaxies are satellites of more luminous galaxies, sharing their massive dark halos. Dr Zehavi and her team will test this hypothesis by examining much larger samples from the SDSS, and comparing the clustering properties of the dim red galaxies to those predicted for satellite dark halos by gravitational N-body simulations. The SDSS data will also be used to examine the distribution of satellite galaxies, comparing the observed anisotropic distribution with predictions from current models in which the satellites form in filaments of the cosmic web. She will use other surveys of more distant galaxies to examine how galaxy clustering has changed over the past 10 billion years of cosmic history. To do this, Dr Zehavi will construct a Halo Occupation Distribution model, which gives a statistical relation between the luminosity and appearance of a galaxy at a given time and the mass of its dark halo. The growth of dark halos can be followed in cosmological N-body simulations, so this model will provide a link between present-day galaxies and their probable precursors, billions of years earlier.
A postdoctoral scholar will be trained by participating in the research; undergraduate students will also be involved. Dr Zehavi will continue to give public-outreach talks at local venues. She will partner with a local museum and planetarium to develop exhibits, and mentor undergraduates working as museum interns.