Bahram Mobasher et al. 2009 ApJ 690 1074 doi:10.1088/0004-637X/690/2/1074
Bahram Mobasher1, Tomas Dahlen2, Andrew Hopkins3, Nick Z. Scoville4, Peter Capak4, R. Michael Rich5, David B. Sanders6, Eva Schinnerer7, Olivier Ilbert6, Mara Salvato4 and Kartik Sheth8
Show affiliationsFor a mass-selected sample of 66544 galaxies with photometric redshifts (z phot) from the Cosmic Evolution Survey (COSMOS), we examine the evolution of star-formation activity as a function of stellar mass in galaxies. We estimate the cosmic star-formation rates (SFRs) over the range 0.2 < z phot < 1.2, using the rest-frame 2800 Å flux (corrected for extinction). We find the mean SFR to be a strong function of the galactic stellar mass at any given redshift, with massive systems (log(M/M
)>10.5) contributing less (by a factor of ~5) to the total star-formation rate density (SFRD). Combining data from the COSMOS and Gemini Deep Deep Survey, we extend the SFRD-z relation as a function of stellar mass to z ~ 2. For massive galaxies, we find a steep increase in the SFRD-z relation to z ~ 2; for the less-massive systems, the SFRD which also increases from z = 0 to 1 levels off at z ~ 1. This implies that the massive systems have had their major star-formation activity at earlier epochs (z > 2) than the lower-mass galaxies. We study changes in the SFRDs as a function of both redshift and stellar mass for galaxies of different spectral types. We find that the slope of the SFRD-z relation for different spectral types of galaxies is a strong function of their stellar mass. For low- and intermediate-mass systems, the main contribution to the cosmic SFRD comes from the star-forming galaxies while, for more-massive systems, the evolved galaxies are the most dominant population.
Issue 2 (2009 January 10)
Received 2008 April 8, accepted for publication 2008 August 18
Published 2008 December 2
Bahram Mobasher et al. 2009 ApJ 690 1074
G. R. Cook et al. 2009 ApJ 704 1021
F. X. Timmes 1999 ApJS 124 241
Peter Laursen et al. 2009 ApJ 696 853
T R Jarboe 1994 Plasma Phys. Control. Fusion 36 945
P.E. Sieck et al 2006 Nucl. Fusion 46 254
S. Kafka et al. 2009 The Astronomical Journal 137 197
K Fahy et al 2004 J. Phys. D: Appl. Phys. 37 3225
Vesa Välimäki et al 2006 Rep. Prog. Phys. 69 1
Stuartt Corder et al 2009 ApJ 690 L65