In and out star formation in z 1.5 quiescent galaxies from rest-frame UV spectroscopy and the far-infrared

Journal
Date Issued
2017
Author(s)
Gobat, R.
•
Daddi, E.
•
•
•
•
Ma, Z.
•
Jin, S.
•
Maraston, C.
•
Magdis, G.
•
Béthermin, M.
•
Cappellari, M.
•
Carollo, M.
•
Cimatti, A.
•
•
Moresco, M.
•
Onodera, M.
•
•
Renzini, A.
•
Sargent, M.
•
Valentino, F.
•
DOI
Abstract
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 ∆age ≤ 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. The stacked VIMOS spectrum of all A+B quality ETGs is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/599/A95
Volume
599
Start page
A95
Uri
Url
Issn Identifier
0004-6361
Ads BibCode
2017A&A...599A..95G
Rights
open.access
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