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

RAPHAEL ALEXANDRE SIMON GOBAT , E. Daddi, V. Strazzullo, B. Garilli, M. Mignoli, Z. Ma, S. Jin, C. Maraston, G. Magdis, M. Béthermin, M. Cappellari, M. Carollo, A. Cimatti, C. Feruglio, M. Moresco, M. Onodera, L. Pozzetti, A. Renzini, M. Sargent, F. ValentinoA. Zanella

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11 Scopus citations


We present a sample of 34 spectroscopically confirmed BzK-selected 1011 M 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 and 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 emission line, with SFROII 3:74:5 M yr1. 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 24 M yr1). This second, photometric sample also displays significant excess at 1.4 GHz, suggestive of the presence of radio-mode AGN activity.

Original languageEnglish
Article numberA95
JournalAstronomy and Astrophysics
StatePublished - 1 Mar 2017


  • Galaxies: elliptical and lenticular, cD
  • Galaxies: formation
  • Galaxies: high-redshift
  • Galaxies: star formation
  • Galaxies: stellar content

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