A1 Refereed original research article in a scientific journal

Probing the Stellar Populations and Star Formation History of Early-type Galaxies at 0 < z < 1.1 in the Rest-frame Ultraviolet




AuthorsAli Sadman S., De Propris Roberto, Chung Chul, Phillipps Steven, Bremer Malcolm N., Onodera Masato, Sawicki Marcin, Desprez Guillaume, Gwyn Stephen

PublisherInstitute of Physics Publishing

Publication year2024

Journal: Astrophysical Journal

Journal name in sourceASTROPHYSICAL JOURNAL

Article number50

Volume966

Issue1

ISSN0004-637X

eISSN1538-4357

DOIhttps://doi.org/10.3847/1538-4357/ad3209

Publication's open availability at the time of reportingOpen Access

Publication channel's open availability Open Access publication channel

Web address https://iopscience.iop.org/article/10.3847/1538-4357/ad3209

Self-archived copy’s web addresshttps://research.utu.fi/converis/portal/detail/Publication/393449796

Preprint addresshttps://arxiv.org/abs/2403.08301


Abstract

We measure the evolution of the rest-frame near-ultraviolet (NUV)-V colors for early-type galaxies in clusters at 0 < z < 1.1 using data from the Hyper Suprime-Cam Subaru Strategic Program, CFHT Large Area U-band Deep Survey, and local Sloan Digital Sky Survey clusters observed with Galaxy Evolution Explorer. Our results show that there is an excess in the ultraviolet spectrum in most quiescent galaxies (compared to the expectations from models fitting their optical/infrared colors and spectra) below z ~ 0.6, beyond which the excess UV emission fades rapidly. This evolution of the UV color is only consistent with the presence of a highly evolved, hot horizontal branch subpopulation in these galaxies (among the majority of cool and optically bright stars), comprising on average 10% of the total stellar mass and forming at z > 3. The blue UV colors of early-type galaxies at low-intermediate redshifts are likely driven by this subpopulation being enriched in helium up to ~44%. At z > 0.8 (when the extra UV component has not yet appeared) the data allow us to constrain the star formation histories of galaxies by fitting models to the evolution of their UV colors: we find that the epoch at which the stellar populations formed lies in the range 3 < zform < 10 (corresponding to 0.5-2.2 Gyr after the Big Bang) with a star formation e-folding timescale of τ = 0.35-0.7 Gyr, suggesting that these galaxies formed the majority of stars at very high redshift, with a brief yet intense burst of star formation activity. The star formation history and chemical evolution of early-type galaxies resemble those of globular clusters, albeit on much larger scales.


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