2007/11/30 by David Schiminovich, Ted K. Wyder, D. Christopher Martin +25 · 4 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Galaxies: Formation, Evolution, Phenomena #Galaxy #Lenticular galaxy #Luminosity function #Luminous infrared galaxy #Peculiar galaxy #Population #Scientific Research and Discoveries #Star formation #Stellar mass #Surface brightness fluctuation #astro-ph
paper · pdf · doi:10.1086/524659
30 pages, 28 figures, scheduled to appear as part of the GALEX Special Ap.J.Suppl., December, 2007 (29 papers)
arxiv created 2007/11/30 · openalex publication_date 2007/12/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We use the UV-optical color magnitude diagram in combination with spectroscopic and photometric measurements derived from the SDSS spectroscopic sample to measure the distribution of galaxies in the local universe ( z < 0.25) and their physical properties as a function of specific star formation rate (SFR/ M ⋆ ) and stellar mass ( M ⋆ ). Throughout this study our emphasis is on the properties of galaxies on and off of a local "star-forming sequence." We discuss how the physical characteristics of galaxies along this sequence are related to scaling relations typically derived for galaxies of different morphological types. We find, among other trends, that our measure of the star formation rate surface density, Σ SFR , is nearly constant along this sequence. We discuss this result and implications for galaxies at higher redshift. For the first time, we report on measurements of the local UV luminosity function versus galaxy structural parameters, as well as inclination. We also split our sample into disk-dominated and bulge-dominated subsamples using the i -band Sersic index and find that disk-dominated galaxies occupy a very tight locus in SFR/ M ⋆ vs. M ⋆ space, while bulge-dominated galaxies display a much larger spread of SFR/ M ⋆ at fixed stellar mass. A significant fraction of galaxies with SFR/ M ⋆ and Σ SFR above those on the "star-forming sequence" are bulge-dominated. We can use our derived distribution functions to ask whether a significant fraction of these galaxies may be experiencing a final episode of star formation (possibly induced by a merger or other burst), soon to be quenched, by determining whether this population can explain the growth rate of the non-star-forming galaxies on the "red sequence." We find that this is a plausible scenario for bulge-dominated galaxies near the characteristic transition mass under reasonable assumptions regarding quenching timescales. Similarly, we use this technique to estimate the rate of mergers/starbursts that take galaxies off of the star-forming sequence and show that the implied merger rates are consistent with local measurements.