2006/11/07 by A. Zirm, Andrew W. Zirm, A. van der Wel +19 · 5 citations
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Elliptical galaxy #Galaxies: Formation, Evolution, Phenomena #Galaxy #Physics #Star formation #Stars #Stellar density #Stellar mass #astro-ph
paper · pdf · doi:10.1086/510713
published as Astrophys.J.656:66-72,2007 · Accepted to The Astrophysical Journal, 8 pages, 5 figures
arxiv created 2006/11/07 · openalex publication_date 2007/02/03 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present deep, high angular-resolution HST NICMOS imaging in the Hubble Deep Field South (HDF-S), focusing on a subset of 14 distant red galaxies (DRGs) at z ~ 2.5 that have been preselected to have J - K > 2.3. We find a clear trend between the rest-frame optical sizes of these sources and their luminosity-weighted stellar ages as inferred from their broadband spectral energy distributions (SEDs). Galaxies whose SEDs are consistent with being dusty and actively star-forming generally show extended morphologies in the NICMOS images ( r e ≳ 2 kpc), while the five sources that are not vigorously forming stars are extremely compact ( r e ≲ 1 kpc). This trend suggests a direct link between the mean ages of the stars and the size and density of the galaxies and supports the conjecture that early events quench star formation and leave compact remnants. Furthermore, the compact galaxies have stellar surface mass densities that exceed those of local galaxies by more than an order of magnitude. The existence of such massive dense galaxies presents a problem for models of early-type galaxy formation and evolution. Larger samples of DRGs and higher spatial resolution imaging will allow us to determine the universality of the results presented here for a small sample.