TY - JOUR
T1 - In and out star formation in z ~ 1.5 quiescent galaxies from rest-frame UV spectroscopy and the far-infrared
AU - Gobat, Raphael
AU - Daddi, Emanuele
AU - Strazzullo, V.
AU - Garilli, Bianca
AU - Mignoli, M.
AU - Ma, Zhibo
AU - Jin, S.
AU - Maraston, C.
AU - Magdis, G.
AU - Béthermin, M.
AU - Cappellari, Michele
AU - Carollo, M.
AU - Cimatti, Andrea
AU - Feruglio, C.
AU - Moresco, Michele
AU - Onodera, M.
AU - Pozzetti, L.
AU - Renzini, Alvio
AU - Sargent, M.
AU - Valentino, F.
AU - Zanella, A.
PY - 2017/3/6
Y1 - 2017/3/6
N2 - We present a sample of 34 spectroscopically confirmed BzK-selected ~1011M⊙ quiescent galaxies (pBzK) in the COSMOS field. The targets were initially observed with VIMOS on the VLT to facilitate the calibration of the photometric redshifts of massive galaxies at z ≳ 1.5. Here we describe the reduction and analysis of the data, and the spectrophotometric properties of these pBzK galaxies. In particular, using a spatially resolved median 2D spectrum, we find that the fraction of stellar populations with ages <1 Gyr is at least 3 times higher in the outer regions of the pBzK galaxies than in their cores. This results in a mild age gradient of Δage ≤ 0.4 Gyr over ~6 kpc and suggests either the occurrence of widespread rejuvenation episodes or that inside-out quenching played a role in the passivization of this galaxy population. We also report on low-level star formation rates derived from the [OII]3727 Å emission line, with SFROII ~ 3.7−4.5M⊙ yr-1. This estimate is confirmed by an independent measurement on a separate sample of similarly-selected quiescent galaxies in the COSMOS field, using stacked far-infrared data (SFRFIR ~ 2−4M⊙ yr-1). This second, photometric sample also displays significant excess at 1.4 GHz, suggestive of the presence of radio-mode AGN activity.
AB - We present a sample of 34 spectroscopically confirmed BzK-selected ~1011M⊙ quiescent galaxies (pBzK) in the COSMOS field. The targets were initially observed with VIMOS on the VLT to facilitate the calibration of the photometric redshifts of massive galaxies at z ≳ 1.5. Here we describe the reduction and analysis of the data, and the spectrophotometric properties of these pBzK galaxies. In particular, using a spatially resolved median 2D spectrum, we find that the fraction of stellar populations with ages <1 Gyr is at least 3 times higher in the outer regions of the pBzK galaxies than in their cores. This results in a mild age gradient of Δage ≤ 0.4 Gyr over ~6 kpc and suggests either the occurrence of widespread rejuvenation episodes or that inside-out quenching played a role in the passivization of this galaxy population. We also report on low-level star formation rates derived from the [OII]3727 Å emission line, with SFROII ~ 3.7−4.5M⊙ yr-1. This estimate is confirmed by an independent measurement on a separate sample of similarly-selected quiescent galaxies in the COSMOS field, using stacked far-infrared data (SFRFIR ~ 2−4M⊙ yr-1). This second, photometric sample also displays significant excess at 1.4 GHz, suggestive of the presence of radio-mode AGN activity.
KW - galaxies: high-redshift
KW - galaxies: elliptical and lenticular, cD
KW - galaxies: formation
KW - galaxies: stellar content
KW - galaxies: star formation
U2 - 10.1051/0004-6361/201629852
DO - 10.1051/0004-6361/201629852
M3 - Article
SN - 0004-6361
VL - 599
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
M1 - A95
ER -