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arXiv · 2005.12289

CLEAR II: Evidence for Early Formation of the Most Compact Quiescent Galaxies at High Redshift

Vicente Estrada-Carpenter·Casey Papovich·Ivelina Momcheva·Gabriel Brammer·Raymond Simons·Joanna Bridge·Nikko J. Cleri·Henry Ferguson·Steven L. Finkelstein·Mauro Giavalisco·Intae Jung·Jasleen Matharu·Jonathan R. Trump·Benjamin Weiner
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Abstract

The origin of the correlations between mass, morphology, quenched fraction, and formation history in galaxies is difficult to define, primarily due to the uncertainties in galaxy star-formation histories. Star-formation histories are better constrained for higher redshift galaxies, observed closer to their formation and quenching epochs. Here we use "non-parametric" star-formation histories and a nested sampling method to derive constraints on the formation and quenching timescales of quiescent galaxies at $0.7 $10.25, where $\Sigma_1$ is the stellar mass within 1~pkpc (proper kpc). Quiescent galaxies with the highest stellar-mass surface density, $\log\Sigma_1 / (M_\odot\ \mathrm{kpc}^{-2}) > 10.25$, } show a \textit{minimum} formation redshift: all such objects in our sample have $z_{50} > 2.9$. Quiescent galaxies with lower surface density, $\log \Sigma_1 / (M_\odot\ \mathrm{kpc}^{-2}) = 9.5 - 10.25$, show a range of formation epochs ($z_{50} \simeq 1.5 - 8$), implying these galaxies experienced a range of formation and assembly histories. We argue that the surface density threshold $\log\Sigma_1/(M_\odot\ \mathrm{kpc}^{-2})>10.25$ uniquely identifies galaxies that formed in the first few Gyr after the Big Bang, and we discuss the implications this has for galaxy formation models.

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Vicente Estrada-Carpenter, Casey Papovich, Ivelina Momcheva, Gabriel Brammer, Raymond Simons, Joanna Bridge, Nikko J. Cleri, Henry Ferguson, Steven L. Finkelstein, Mauro Giavalisco, Intae Jung, Jasleen Matharu, Jonathan R. Trump, Benjamin Weiner. 2020-05-25. CLEAR II: Evidence for Early Formation of the Most Compact Quiescent Galaxies at High Redshift. https://doi.org/10.3847/1538-4357/aba004

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