The evolution of the mass-size relation to z=3.5 for UV-bright galaxies and sub-mm galaxies in the GOODS-NORTH field

TL;DR

This study examines how the sizes of UV-bright and sub-mm galaxies evolve with redshift up to z=3.5, revealing size growth over time and similarities between different galaxy types in the GOODS-North field.

Contribution

It provides the first detailed comparison of size evolution for UV-bright and sub-mm galaxies up to z=3.5 using spectroscopic data and rest-frame optical imaging.

Findings

Galaxy sizes at fixed mass decrease with redshift as (1+z)^{-1.11}

UV-bright galaxies are larger than quiescent galaxies at similar redshifts and masses

Sub-mm galaxies have median sizes comparable to UV-bright star-forming galaxies

Abstract

We study the evolution of the size - stellar mass relation for a large spectroscopic sample of galaxies in the GOODs North field up to $z \sim 3.5$. The sizes of the galaxies are measured from $\textit{K}_{s}$-band images (corresponding to rest-frame optical/NIR) from the Subaru 8m telescope. We reproduce earlier results based on photometric redshifts that the sizes of galaxies at a given mass evolve with redshift. Specifically, we compare sizes of UV-bright galaxies at a range of redshifts: Lyman break galaxies (LBGs) selected through the U-drop technique ($z \sim 2.5-3.5$), BM/BX galaxies at $z \sim 1.5-2.5$, and GALEX LBGs at low redshift ($z \sim 0.6-1.5$). The median sizes of these UV-bright galaxies evolve as $(1+z)^{-1.11\pm0.13}$ between $z \sim 0.5-3.5$. The UV-bright galaxies are significantly larger than quiescent galaxies at the same mass and redshift by $0.45\pm0.09$ dex. We also verify the correlation between color and stellar mass density of galaxies to high redshifts. The sizes of sub-mm galaxies in the same field are measured and compared with BM/BX galaxies. We find that median half-light radii of SMGs is $2.90 \pm 0.45$ kpc and there is little difference in their size distribution to the UV-bright star forming galaxies.