J/A+A/599/A95 Star formation in z∼1.5 quiescent galaxies (Gobat+, 2017)
In and out star formation in z∼1.5 quiescent galaxies from rest-frame UV
spectroscopy and the far infrared.
Gobat R., Daddi E., Strazzullo V., Garilli B., Mignoli M., Ma Z., Jin S.,
Maraston C., Bethermin M., Cappellari M., Carollo M., Cimatti A.,
Feruglio C., Moresco M., Onodera M., Pozzetti L., Renzini A., Valentino F.,
Zanella A.
<Astron. Astrophys. 599, A95 (2017)>
=2017A&A...599A..95G 2017A&A...599A..95G (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, spectra
Keywords: galaxies: high-redshift - galaxies: elliptical and lenticular, cD -
galaxies: formation - galaxies: stellar content -
galaxies: star formation
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 <1Gyr 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 {DELTA}age≤0.4Gyr over
∼6kpc 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]3727Å emission line,
with SFROII∼3.7-4.5M☉/yr. 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). This second, photometric sample also
displays significant excess at 1.4GHz, suggestive of the presence of
radio-mode AGN activity.
Description:
Median VIMOS spectrum of 31 BzK-selected massive quiescent galaxies in
the COSMOS field, with a median redshift of z=1.5. The observations
were carried out during ESO programs 086.A-0681 and 088.A-0671 using
the medium resolution grism and GG475 order-sorting filter, with a
slit width of 1-arcsec. The 2D data were reduced with VIPGI pipeline,
and corrected for redshift and cosmological dimming before stacking.
The 1D spectrum was extracted using a 12-pixel aperture.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 23 1599 Median 1D VIMOS spectrum of z∼1.5 ETGs
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 F7.2 0.1nm lambda Rest-frame wavelength
10- 15 F6.4 --- Flux Flux, F(lambda) (1)
18- 23 F6.4 --- e_Flux Standard error on Flux (1)
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Note (1): Flux and standard error are in arbitrary units.
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Acknowledgements:
Raphael Gobat, rgobat(at)kias.re.kr
(End) Raphael Gobat [KIAS, South Korea], Patricia Vannier [CDS] 27-Dec-2016