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| Paper: |
A Constant Characteristic Mass for Star Forming Galaxies since z∼3 Revealed by Radio Emission in the COSMOS Field |
| Volume: |
446, Galaxy Evolution: Infrared to Millimeter Wavelength Perspective |
| Page: |
269 |
| Authors: |
Karim, A.; Schinnerer, E. |
| Abstract: |
We present results of our 1.4 GHz image stacking analysis of mass-selected galaxies in the COSMOS field. From the
resulting median radio continuum flux density we have determined the evolution of the average star formation rate (SFR) of
galaxies as a function of stellar mass, unbiased from effects of dust but also source confusion due to the 1.5" angular
resolution achieved by the VLA. We find a power-law relation between specific SFR (SSFR) and stellar mass for star forming
galaxies out to z=3. While higher mass systems exhibit lower SSFRs at any epoch, no differential, more rapid evolution of
high mass galaxies is evident at least out to z∼1.5 where our conclusions are most robust. Utilizing measured mass
functions of star forming systems, the characteristic stellar mass for galaxies contributing most to the comoving SFR density appears not to evolve. These findings hence challenge ‘downsizing’ scenarios in which star formation has gradually
shifted towards lower mass systems with cosmic time. Our analysis constitutes the to-date best determination of the cosmic
star formation history (CSFH) since z = 3 and yields indirect evidence for a rapid decline of the global mass density of
molecular gas with time. |
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