TY - JOUR

T1 - COSMOS2020

T2 - Exploring the Dawn of Quenching for Massive Galaxies at 3 < z < 5 with a New Color-selection Method

AU - Gould, Katriona M. L.

AU - Brammer, Gabriel

AU - Valentino, Francesco

AU - Whitaker, Katherine E.

AU - Weaver, John. R.

AU - Lagos, Claudia del P.

AU - Rizzo, Francesca

AU - Franco, Maximilien

AU - Hsieh, Bau-Ching

AU - Ilbert, Olivier

AU - Jin, Shuowen

AU - Magdis, Georgios

AU - J. McCracken, Henry

AU - Mobasher, Bahram

AU - Shuntov, Marko

AU - Steinhardt, Charles L.

AU - Strait, Victoria

AU - Toft, Sune

PY - 2023/5/23

Y1 - 2023/5/23

N2 - We select and characterize a sample of massive (log(M (*)/M (circle dot)) > 10.6) quiescent galaxies (QGs) at 3 < z < 5 in the latest Cosmological Evolution Survey catalog (COSMOS2020). QGs are selected using a new rest-frame color-selection method, based on their probability of belonging to the quiescent group defined by a Gaussian mixture model (GMM) trained on rest-frame colors (NUV - U, U - V, V - J) of similarly massive galaxies at 2 < z < 3. We calculate the quiescent probability threshold above which a galaxy is classified as quiescent using simulated galaxies from the shark semi-analytical model. We find that, at z >= 3 in shark, the GMM/NUVU - VJ method outperforms classical rest-frame UVJ selection and is a viable alternative. We select galaxies as quiescent based on their probability in COSMOS2020 at 3 < z < 5, and compare the selected sample to both UVJ- and NUVrJ-selected samples. We find that, although the new selection matches UVJ and NUVrJ in number, the overlap between color selections is only similar to 50%-80%, implying that rest-frame color commonly used at lower-redshift selections cannot be equivalently used at z > 3. We compute median rest-frame spectral energy distributions for our sample and find the median QG at 3 < z < 5 has a strong Balmer/4000 angstrom break, and residual NUV flux indicating recent quenching. We find the number densities of the entire quiescent population (including post-starbursts) more than doubles from 3.5 +/- 2.2 x 10(-6) Mpc(-3) at 4 < z < 5 to 1.4 +/- 0.4 x 10(-5) Mpc(-3) at 3 < z < 4, confirming that the onset of massive galaxy quenching occurs as early as 3 < z < 5.

AB - We select and characterize a sample of massive (log(M (*)/M (circle dot)) > 10.6) quiescent galaxies (QGs) at 3 < z < 5 in the latest Cosmological Evolution Survey catalog (COSMOS2020). QGs are selected using a new rest-frame color-selection method, based on their probability of belonging to the quiescent group defined by a Gaussian mixture model (GMM) trained on rest-frame colors (NUV - U, U - V, V - J) of similarly massive galaxies at 2 < z < 3. We calculate the quiescent probability threshold above which a galaxy is classified as quiescent using simulated galaxies from the shark semi-analytical model. We find that, at z >= 3 in shark, the GMM/NUVU - VJ method outperforms classical rest-frame UVJ selection and is a viable alternative. We select galaxies as quiescent based on their probability in COSMOS2020 at 3 < z < 5, and compare the selected sample to both UVJ- and NUVrJ-selected samples. We find that, although the new selection matches UVJ and NUVrJ in number, the overlap between color selections is only similar to 50%-80%, implying that rest-frame color commonly used at lower-redshift selections cannot be equivalently used at z > 3. We compute median rest-frame spectral energy distributions for our sample and find the median QG at 3 < z < 5 has a strong Balmer/4000 angstrom break, and residual NUV flux indicating recent quenching. We find the number densities of the entire quiescent population (including post-starbursts) more than doubles from 3.5 +/- 2.2 x 10(-6) Mpc(-3) at 4 < z < 5 to 1.4 +/- 0.4 x 10(-5) Mpc(-3) at 3 < z < 4, confirming that the onset of massive galaxy quenching occurs as early as 3 < z < 5.

KW - POST-STARBURST GALAXIES

KW - STELLAR POPULATION SYNTHESIS

KW - STAR-FORMATION HISTORIES

KW - HUBBLE-SPACE-TELESCOPE

KW - SIMILAR-TO 4

KW - LESS-THAN 6

KW - QUIESCENT GALAXIES

KW - SPECTROSCOPIC CONFIRMATION

KW - PHYSICAL-PROPERTIES

KW - PASSIVE GALAXIES

U2 - 10.3847/1538-3881/accadc

DO - 10.3847/1538-3881/accadc

M3 - Journal article

VL - 165

JO - The Astronomical Journal

JF - The Astronomical Journal

SN - 0004-6256

IS - 6

M1 - 248

ER -