JADES: deep spectroscopy of a low-mass galaxy at redshift 2.3 quenched by environment

JADES: deep spectroscopy of a low-mass galaxy at redshift 2.3 quenched by environment

Jul 17, 2023·
Lester Sandles
,
Francesco D'Eugenio
Jakob M. Helton
Jakob M. Helton
,
Roberto Maiolino
,
Kevin Hainline
,
William M. Baker
,
Christina C. Williams
,
Stacey Alberts
,
Andrew J. Bunker
,
Stefano Carniani
,
Stephane Charlot
,
Jacopo Chevallard
,
Mirko Curti
,
Emma Curtis-Lake
,
Daniel J. Eisenstein
,
Zhiyuan Ji
,
Benjamin D. Johnson
,
Tobias J. Looser
,
Tim Rawle
,
Brant Robertson
,
Bruno Rodrı́guez Del Pino
,
Sandro Tacchella
,
Hannah Übler
,
Christopher N. A. Willmer
,
Chris Willott
Abstract
We report the discovery of a quiescent galaxy at z=2.34z = 2.34 with a stellar mass of only M=9.51.2+1.8×108 MM_{\ast} = 9.5_{-1.2}^{+1.8} \times 10^{8}\ M_{\odot} , based on deep JWST/NIRSpec spectroscopy. This is the least massive quiescent galaxy found so far at high redshift. We use a Bayesian approach to model the spectrum and photometry, and find the target to have been quiescent for 0.6 Gyr0.6\ \mathrm{Gyr} with a mass-weighted average stellar age of 0.81.7 Gyr0.8-1.7\ \mathrm{Gyr} (dominated by systematics). The galaxy displays an inverse colour gradient with radius, consistent with environment-driven quenching. Based on a combination of spectroscopic and robust (medium- and broad-band) photometric redshifts, we identify a galaxy overdensity near the location of the target (5σ5\sigma above the background level at this redshift). We stress that had we been specifically targetting galaxies within overdensities, the main target would not have been selected on photometry alone; therefore, environment studies based on photometric redshifts are biased against low-mass quiescent galaxies. The overdensity contains three spectroscopically confirmed, massive, old galaxies (M=817×1010MM_{\ast} = 8-17 \times 10^{10} M_{\odot} ). The presence of these evolved systems points to accelerated galaxy evolution in overdensities at redshifts z>2z > 2 , in agreement with previous works. In projection, our target lies only 35 pkpc35\ \mathrm{pkpc} away from the most massive galaxy in this overdensity (spectroscopic redshift z=2.349z = 2.349 ) which is located close to overdensity’s centre. This suggests the low-mass galaxy was quenched by environment, making it possibly the earliest evidence for environment-driven quenching to date.
Type
Publication
eprint arXiv:2307.08633