Diagnosing DASH: A Catalog of Structural Properties for the COSMOS-DASH Survey

TL;DR

This paper presents a comprehensive catalog of galaxy morphologies from the COSMOS-DASH survey, demonstrating the survey's effectiveness in measuring galaxy structures up to redshift 2 over a large area, and revealing insights into galaxy size-mass relations.

Contribution

It provides the largest area near-IR galaxy morphological catalog from HST-WFC3 using the Drift And SHift technique, with robust size and structure measurements extending to high redshift.

Findings

Galaxy sizes and Sersic indices are accurate to certain magnitude limits.

Galaxies show a flattening in the size-mass relation below a stellar mass of 10^10.5 M_sun.

Environmental effects are not the main driver of the observed size-mass relation flattening.

Abstract

We present the $H_{160}$ morphological catalogs for the COSMOS-DASH survey, the largest area near-IR survey using HST-WFC3 to date. Utilizing the "Drift And SHift" observing technique for HST-WFC3 imaging, the COSMOS-DASH survey imaged approximately 0.5 deg$^2$ of the UltraVISTA deep stripes (0.7 deg$^2$ when combined with archival data). Global structural parameters are measured for 51,586 galaxies within COSMOS-DASH using GALFIT (excluding the CANDELS area) with detection using a deep multi-band HST image. We recover consistent results with those from the deeper 3D-HST morphological catalogs, finding that, in general, sizes and S\'ersic indices of typical galaxies are accurate to limiting magnitudes of $H_{160}<23$ and $H_{160}<22$ ABmag, respectively. In size-mass parameter space, galaxies in COSMOS-DASH demonstrate robust morphological measurements out to $z\sim2$ and down to $\log(M_\star/M_\odot)\sim9$. With the advantage of the larger area of COSMOS-DASH, we measure a flattening of the quiescent size-mass relation below $\log(M_\star/M_\odot)\sim10.5$ that persists out to $z\sim2$. We show that environment is not the primary driver of this flattening, at least out to $z=1.2$, whereas internal physical processes may instead govern the structural evolution.