Spitzer View on the Evolution of Star‐forming Galaxies from z= 0 to z∼ 3

Abstract

We use a 24 μm-selected sample containing more than 8000 sources to study the evolution of star-forming galaxies in the redshift range from z = 0 to z ~ 3. We obtain photometric redshifts for most of the sources in our survey using a method based on empirically built templates spanning from ultraviolet to mid-infrared wavelengths. The accuracy of these redshifts is better than 10% for 80% of the sample. The derived redshift distribution of the sources detected by our survey peaks at around z = 0.6-1.0 (the location of the peak being affected by cosmic variance) and decays monotonically from z ~ 1 to z ~ 3. We have fitted infrared luminosity functions in several redshift bins in the range 0 < z ≲ 3. Our results constrain the density and/or luminosity evolution of infrared-bright star-forming galaxies. The typical infrared luminosity ( L *) decreases by an order of magnitude from z ~ 2 to the present. The cosmic star formation rate (SFR) density goes as (1 + z ) 4.0±0.2 from z = 0 to 0.8. From z = 0.8 to z ~ 1.2, the SFR density continues rising with a smaller slope. At 1.2 < z ≲ 3, the cosmic SFR density remains roughly constant. The SFR density is dominated at low redshift ( z ≲ 0.5) by galaxies that are not very luminous in the infrared ( L TIR < 10 11 L ☉ , where L TIR is the total infrared luminosity, integrated from 8 to 1000 μm). The contribution from luminous and ultraluminous infrared galaxies ( L TIR > 10 11 L ☉ ) to the total SFR density increases steadily from z ~ 0 up to z ~ 2.5, forming at least half of the newly born stars by z ~ 1.5. Ultraluminous infrared galaxies ( L TIR > 10 12 L ☉ ) play a rapidly increasing role for z ≳ 1.3.