Minor Merger Growth in Action: JWST Detects Faint Blue Companions around Massive Quiescent Galaxies at 0.5 ≤ z ≤ 3.0 - Institut d'Astrophysique de Paris Access content directly
Journal Articles The Astrophysical journal letters Year : 2023

Minor Merger Growth in Action: JWST Detects Faint Blue Companions around Massive Quiescent Galaxies at 0.5 ≤ z ≤ 3.0

Katherine A Suess
Christina C Williams
Brant Robertson
Zhiyuan Ji
Benjamin D Johnson
Erica Nelson
Stacey Alberts
Kevin Hainline
Francesco D’eugenio
Hannah Übler
Marcia Rieke
George Rieke
Andrew J Bunker
Stefano Carniani
Stephane Charlot
Daniel J Eisenstein
Roberto Maiolino
Daniel P Stark
Sandro Tacchella
Chris Willott

Abstract

Abstract Minor mergers are thought to drive the structural evolution of massive quiescent galaxies; however, existing Hubble Space Telescope (HST) imaging is primarily sensitive to stellar mass ratios ≳1:10. Here, we report the discovery of a large population of low-mass companions within 35 kpc of known log M * / M ⊙ ≳ 10.5 quiescent galaxies at 0.5 ≤ z ≤ 3. While massive companions like those identified by HST are rare, JWST imaging from the JWST Advanced Deep Extragalactic Survey reveals that the average massive quiescent galaxy hosts approximately five nearby companions with stellar mass ratios <1:10. Despite a median stellar mass ratio of just 1:900, these tiny companions are so numerous that they represent at least 30% of the total mass being added to quiescent galaxies via minor mergers. While relatively massive companions have colors similar to their hosts, companions with mass ratios <1:10 typically have bluer colors and lower mass-to-light ratios than their host galaxies at similar radii. The accretion of these tiny companions is likely to drive evolution in the color gradients and stellar population properties of the host galaxies. Our results suggest that the well-established “minor merger growth” model for quiescent galaxies extends down to very low mass ratios of ≲1:100, and demonstrates the power of JWST to constrain both the spatially resolved properties of massive galaxies and the properties of low-mass companions beyond the local Universe.
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hal-04293558 , version 1 (18-11-2023)

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Katherine A Suess, Christina C Williams, Brant Robertson, Zhiyuan Ji, Benjamin D Johnson, et al.. Minor Merger Growth in Action: JWST Detects Faint Blue Companions around Massive Quiescent Galaxies at 0.5 ≤ z ≤ 3.0. The Astrophysical journal letters, 2023, 956 (2), pp.L42. ⟨10.3847/2041-8213/acf5e6⟩. ⟨hal-04293558⟩
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