An enhanced merger fraction within the galaxy population of the SSA22 protocluster at z ~ 3.1

Abstract

The over-dense environments of protoclusters of galaxies in the early Universe (z>2) are expected to accelerate the evolution of galaxies, with an increased rate of stellar mass assembly and black hole accretion compared to co-eval galaxies in the average density `field'. These galaxies are destined to form the passive population of massive systems that dominate the cores of rich clusters today. While signatures of accelerated growth of galaxies in the SSA22 protocluster (z=3.1) have been observed, the mechanism driving this remains unclear. Here we show an enhanced rate of galaxy-galaxy mergers could be responsible. We morphologically classify Lyman-break Galaxies (LBGs) in the SSA22 protocluster and compare these to those of galaxies in the field at z=3.1 as either active mergers or non-merging using Hubble Space Telescope ACS/F814W imaging, probing the rest-frame ultraviolet stellar light. We measure a merger fraction of 48+/-10 per cent for LBGs in the protocluster compared to 30+/-6 per cent for the field. Although the excess is marginal, an enhanced rate of mergers in SSA22 hints that galaxy-galaxy mergers are one of the key channels driving accelerated star formation and AGN growth in protocluster environments.

Accepted MNRAS 2015 October 20

References in corpus (11)

• Formation of Massive Galaxies at High Redshift: Cold Streams, Clumpy Disks and Compact Spheroids
• The Evolution of Galaxy Structure over Cosmic Time
• 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
• Protoclusters associated with z > 2 radio galaxies. I. Characteristics of high redshift protoclusters
• Environmental Dependence of Dark Matter Halo Growth I: Halo Merger Rates
• Spatial correlation between submillimetre and Lyman-alpha galaxies in the SSA 22 protocluster
• A Surprisingly High Pair Fraction for Extremely Massive Galaxies at z ~ 3 in the GOODS NICMOS Survey
• The growth and assembly of a massive galaxy at z ~ 2
• NIR spectroscopic observation of massive galaxies in the protocluster at z = 3.09
• Measuring galaxy morphology at $z>1$. I - calibration of automated proxies

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