COSMOS-DASH : the evolution of the galaxy size-mass relation since z ∼ 3 from new wide-field WFC3 imaging combined with CANDELS/3D-HST

Subtitle:COSMOS-DASH : the evolution of the galaxy size-mass relation since z similar to 3 from new wide-field WFC3 imaging combined with CANDELS/3D-HST

We present COSMOS-Drift And SHift (DASH), a Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) imaging survey of the COSMOS field in the H-160 filter. The survey comprises 456 individual WFC3 pointings corresponding to an area of 0.49 deg(2) (0.66 deg(2) when including archival data) and reaches a 5 sigma point-source limit of H-160 = 25.1 (0 ''.3 aperture). COSMOS-DASH is the widest HST/WFC3 imaging survey in the H-160 filter, tripling the extragalactic survey area in the near-infrared at HST resolution. We make the reduced H-160 mosaic available to the community. We use this data set to measure the sizes of 169 galaxies with log(M-star/M) > 11.3 at 1.5 < z < 3.0 and augment this sample with 749 galaxies at 0.1 < z < 1.5 using archival ACS imaging. We find that the median size of galaxies in this mass range changes with redshift as < r(eff)> = (13.4 +/- 0.5) x (1 + z)((-0.95 +/- 0.05)) kpc. Separating the galaxies into star-forming and quiescent galaxies using their rest-frame U - V and V - J colors, we find no statistical difference between the median sizes of the most massive star-forming and quiescent galaxies at < z > = 2.5: they are 4.9 +/- 0.9 kpc and 4.3 +/- 0.3 kpc, respectively. However, we do find a significant difference in the Sersic index between the two samples, such that massive quiescent galaxies have higher central densities than star-forming galaxies. We extend the size-mass analysis to lower masses by combining it with the 3D-HST/CANDELS sample of van der Wel et al. and derive empirical relations between size, mass, and redshift. Fitting a relation of the form r(eff) = A x m(star)(alpha) with m(star) = M-star/5 x 10(10) M-circle dot and r(eff) in kpc, we find log A = -0.25 log(1 + z) + 0.80 and alpha = -0.13 log(1 + z) + 0.27. We also provide relations for the subsamples of star-forming and quiescent galaxies. Our results confirm previous studies that were based on smaller samples or ground-based imaging.

Publication year:2019

BOF-keylabel:yes

IOF-keylabel:yes

BOF-publication weight:3

CSS-citation score:1

Authors:International

Authors from:Higher Education

Accessibility:Open