Environmental impacts on the rest-frame UV size and morphology ofstar-forming galaxies at $z\sim 2$

Abstract

We report the measurement of rest-frame UV size and morphology of H$\alpha$-emission-selected star-forming galaxies (HAEs) in four protoclusters at z $\sim$ 2 (PKS 1138-262, USS 1558-003, PHz G237.0+42.5, and CC 2.2) using archival Hubble Space Telescope Advanced Camera Surveys (HST/ACS) F814W data. We compare the measurement of 122 HAEs in protoclusters detected by HST/ACS to a coeval comparison field sample of 436 HAEs. We find the size distributions of protocluster and field HAEs are similar with typical half-light radius of $\sim$ 2.5 kpc. At fixed stellar mass, there is no significant difference between HAE in protocluster and in field, which is also supported by stacking analyses. This result suggests that the environment does not significantly affect the size of galaxies during the star-forming phase at this epoch. Based on Sérsic index and non-parametric morphologies, HAE morphologies in both environments at $z\sim 2$ in rest-frame UV are consistent with disk-like star-forming galaxies, although we also find $29\%\pm 4\%$ HAEs have peculiar or disturbed morphologies. The fraction of disturbed galaxies is higher in protocluster environment, with $39\pm 8\%$ protocluster HAEs showing disturbed morphologies, compared to $26\pm 4\%$ in the comparison field. The apparent disturbed morphologies are correlated with higher star-formation activity and may be caused by either in situ giant clumps or mergers.

28 pages. Accepted for publication by The Astrophysical Journal

References in corpus (26)

• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• 3D-HST+CANDELS: The Evolution of the Galaxy Size-Mass Distribution since $z=3$
• Formation of Massive Galaxies at High Redshift: Cold Streams, Clumpy Disks and Compact Spheroids
• UltraVISTA: a new ultra-deep near-infrared survey in COSMOS
• The Evolution of Galaxy Structure over Cosmic Time
• Weak Gravitational Lensing with COSMOS: Galaxy Selection and Shape Measurements
• Galaxy Merger Morphologies and Time-Scales from Simulations of Equal-Mass Gas-Rich Disc Mergers
• The Structures of Distant Galaxies I: Galaxy Structures and the Merger Rate to z~3 in the Hubble Ultra-Deep Field
• The First Appearance of the Red Sequence of Galaxies in Proto-Clusters at 2<~z<~3
• An excess of dusty starbursts related to the Spiderweb galaxy
• The Spiderweb galaxy: a forming massive cluster galaxy at z~2
• MAHALO Deep Cluster Survey I. Accelerated and enhanced galaxy formation in the densest regions of a protocluster at z=2.5
• The Size Evolution of Star-forming Galaxies Since z~7 Using ZFOURGE
• Diverse Structural Evolution at z > 1 in Cosmologically Simulated Galaxies
• The effect of the environment on the stellar mass - size relation of present-day galaxies
• Proto-Clusters with Evolved Populations around Radio Galaxies at z~2.5
• HST/WFC3 grism observations of $z\sim 1$ clusters: The cluster vs. field stellar mass-size relation and evidence for size growth of quiescent galaxies from minor mergers
• The structural and size evolution of star-forming galaxies over the last 11 Gyrs
• Spectroscopic observations of PHz G237.01+42.50: A galaxy protocluster at z=2.16 in the Cosmos field
• Signs of environmental effects on star-forming galaxies in the Spiderweb protocluster at z=2.16
• The Differential Size Growth of Field and Cluster Galaxies at z=2.1 Using the ZFOURGE Survey
• The Morphology-Density relationship in 1<z<2 clusters
• Enhanced Star Formation of Less Massive Galaxies in a Proto-Cluster at z=2.5
• Morphologies of Galaxies in and around a Protocluster at z=2.300
• Accelerated galaxy growth and environmental quenching in a protocluster at z=3.24
• ZFIRE: Similar Stellar Growth in H$\alpha$-emitting Cluster and Field Galaxies at z~2