Accelerated galaxy growth and environmental quenching in a protocluster at z=3.24

TL;DR

This study investigates galaxy growth and environmental effects in a protocluster at z=3.24, revealing accelerated mass assembly and a higher fraction of quiescent galaxies in dense regions, indicating early environmental quenching.

Contribution

It provides the first detailed analysis of galaxy evolution and environmental quenching in a high-redshift protocluster at z=3.24, highlighting accelerated growth in dense environments.

Findings

Higher quiescent galaxy fraction in the protocluster

Evidence of accelerated galaxy formation in dense regions

Weak indication of star formation suppression

Abstract

We present a multiwavelength study of galaxies around D4UD01, a spectroscopically confirmed protocluster at z = 3.24 to investigate environmental trends. 450 galaxies are selected based on Ks band detection with photometric redshifts (photo-z) at 3.0 < z < 3.4, among which ~ 12% are classified as quiescent galaxies. The quiescent galaxies are among the most massive and reddest ones in the entire sample. We identify a large photo-z galaxy overdensity in the field, which lies close to the previously spectroscopically confirmed sources of the protocluster. We find that the quiescent galaxies are largely concentrated in the overdense protocluster region with a higher quiescent fraction, showing a sign of environmental quenching. Galaxies in the protocluster are forming faster than the field counterparts as seen in the stellar mass function, suggesting early and accelerated mass assembly in the overdense regions. Although weak evidence of suppressed star-formation is found in the protocluster, the statistics are not significant enough to draw a definite conclusion. Our work shed light on how the formation of massive galaxies is affected in the dense region of a protocluster when the Universe was only 2 Gyr old.