Merger-Induced Populations in Early-Type Galaxy Cores
Abstract
Hierarchical formation models predict that early-type galaxies are built up over an extended period from mergers of smaller systems, a process which should leave long-lived signatures in their light profiles and stellar population colors. Merger events should have continued up to relatively recent times {the last 1-5 Gyr}, and many ellipticals and S0 bulges should therefore show evidence of multiple, discrete, intermediate-age populations. Although there is substantial observational support for a dissipational merger origin for some early-type galaxies, most do not exhibit the expected anomalies in either their light profiles or color distributions. However, existing searches {mainly in the V and I bands} have not probed very deeply. Here we propose high resolution, broad-band, near-ultraviolet {2500-3400 A} imaging of the cores of bright early-type galaxies. This is the most sensitive probe available for the detection of spatially-segregated, multiple population components with ages in the range 1-5 Gyr. Our sample consists of dust- and AGN-free systems with both normal and mildly anomalous central light profiles. There is very little existing information on the near-UV structure of early-type galaxies, and our program would effectively explore new terrain.
- Publication:
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HST Proposal
- Pub Date:
- July 2004
- Bibcode:
- 2004hst..prop10435O