IPMU Colloquium

Speaker: Kevin Bundy (UC Berkeley)
Title: How are Massive Galaxies Built Over Cosmic Time?
Date (JST): Wed, Dec 08, 2010, 15:30 - 17:00
Place: Lecture Hall
Related File: 397.pdf
Abstract: The physical processes that regulate the growth of massive galaxies remain poorly understood. In the LCDM framework, we expect massive galaxies to assemble their mass at late times, but many observations have claimed the opposite trend. Previous work, however, has been severely limited by the small volumes of past galaxy redshift surveys which could not provide robust samples of these very rare objects. Thankfully, an array of next-generation wide-field surveys--including the planned SuMIRe program--will bring definitive answers. I will discuss early steps to measure massive galaxy assembly with one such survey, the recently-commissioned Baryon Oscillation Spectroscopic Survey (BOSS). With the degree of growth measured from BOSS, the mechanisms responsible for this growth can be tested with targeted followup observations and compared to theoretical models. As an example, I will focus on a sample of distant Brightest Central Galaxies (BCGs) identified in massive galaxy groups. Despite a larger incidence of morphological disturbances and apparently merging companions compared to non-group galaxies of a similar mass, our sample of ~50 BCGs has internal velocities and structures that are similar to the non-group counterparts. This tells us they have not experienced many violent mergers in the recent past and tentatively suggests that the assembly rate of the most massive galaxies may be suppressed by their environment.