The Evolution of the Cosmic Stellar Mass Density out to z=3
Abstract
We present a measurement of the evolution in the stellar mass density from z=0 to z=3 using a combination of the extremely-deep optical data from HST in the Hubble Deep Field South (HDF-S) and the very deep near infrared (NIR) imaging data taken at the VLT. To pick galaxies in a way as close as possible to a selection by stellar mass we detect our objects in the Ks-band, which provides access to rest-frame optical wavelengths out to z ∼ 4. We derive accurate photometric redshifts for galaxies at z<3.2 that are as faint as 0.5 L* in the rest-frame optical. The rest-frame V-band luminosity density is constant to within a factor of ∼ 3 out to z=3.2, while the mean cosmic rest-frame (U-B) and (B-V) colors become significantly bluer towards higher redshifts. We estimate the mean cosmic V-band stellar mass-to-light ratios (M/LV) from our mean cosmic colors and, in the presence of bursty star formation histories (SFHs) for individual galaxies, suffer 3 times lower errors than the mean of the individual M/LV estimates, when compared to the true values. We use our global M/LV estimates, in conjunction with our rest-frame luminosity density estimates, to estimate the cosmic stellar mass density evolution out to z=3.2. While the luminosity density in the V-band is constant to within a factor of ∼ 3, the inferred M/LV decreases by a factor of ∼ 20 from z=0 to z=3.2 and the inferred stellar mass density decreases by a factor of ∼ 10. Comparison with other fields shows that cosmic variance plays a strong role but, nevertheless, our results are marginally consistent with those derived by other authors in HDF-N and are in agreement with the integrated SFR(z) curve, once corrected for extinction, implying a large fraction of stars in the universe formed between z=1-2.
- Publication:
-
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 2003
- Bibcode:
- 2003AAS...20314611R