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|Title:||In and out star formation in z 1.5 quiescent galaxies from rest-frame UV spectroscopy and the far-infrared||Authors:||Gobat, R.
GARILLI, BIANCA MARIA ROSA
|Issue Date:||2017||Journal:||ASTRONOMY & ASTROPHYSICS||Number:||599||First Page:||A95||Abstract:||We present a sample of 34 spectroscopically confirmed BzK-selected 10<SUP>11</SUP>M<SUB>☉</SUB> 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 SFR<SUB>OII</SUB> 3.7-4.5M<SUB>☉</SUB> yr<SUP>-1</SUP>. 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 (SFR<SUB>FIR</SUB> 2-4M<SUB>☉</SUB> yr<SUP>-1</SUP>). 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 <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (<A href="http://126.96.36.199">http://188.8.131.52</A>) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/599/A95">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/599/A95||URI:||http://hdl.handle.net/20.500.12386/27054||URL:||https://www.aanda.org/articles/aa/abs/2017/03/aa29852-16/aa29852-16.html||ISSN:||0004-6361||DOI:||10.1051/0004-6361/201629852||Bibcode ADS:||2017A&A...599A..95G||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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checked on Sep 21, 2020
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