J/A+A/633/A70 VIS3COS. III. Galaxy spectra (Paulino-Afonso+, 2020)
VIS3COS. III. Environmental effects on the star formation histories of galaxies
at z∼0.8 seen in [OII], Hδ, and Dn4000.
Paulino-Afonso A., Sobral D., Darvish B., Ribeiro B., Smail I., Best P.,
Stroe A., Cairns J.
<Astron. Astrophys. 633, A70 (2020)>
=2020A&A...633A..70P 2020A&A...633A..70P (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Galaxies, spectra ; Optical
Keywords: galaxies: evolution - galaxies: high redshift -
galaxies: star formation - large-scale structure of Universe
Abstract:
We present spectroscopic observations of 466 galaxies in and around a
superstructure at z∼0.84 targeted by the VIMOS Spectroscopic Survey of
a Supercluster in the COSMOS eld (VIS3COS). We use [OII]3727,
Hδ, and Dn4000 to trace recent, medium-, and long-term star
formation histories and investigate the eect of stellar mass and local
environment on them. By studying trends in individual and composite
galaxy spectra, we find that stellar mass and environment play a role
in the observed galactic properties. Galaxies with low stellar mass
(10<log10(M*/M☉)<10.5) in the eld show the strongest Hδ
absorption. Similarly, the massive population (log10(M*/M☉) >
11) shows an increase in H absorption strengths in
intermediate-density environments (e.g. filaments). Galaxies with
intermediate stellar mass (10.5<log10(M*/M☉)<11) have similar
Hδ absorption proles in all environments, but show an indication
of enhanced [OII] emission in intermediate-density environments. This
indicates that field galaxies with low stellar mass and lament
galaxies with high stellar mass are more likely to have experienced a
recent burst of star formation, while galaxies of the intermediate
stellar-mass show an increase of star formation at lament-like
densities. We also find that the median [OII] equivalent width
(|EW[OII]|) decreases from 27±2Å to 2.0+0,5-0.4Å and
Dn4000 increases from 1.09±0.01 to 1.56±0.03 with increasing
stellar mass (from ∼109.25 to ∼1011.35M☉). For the
dependence on the environment, we find that at fixed stellar mass,
|EW[OII]| is tentatively lower in environments with higher density. We
find for Dn4000 that the increase with stellar mass is sharper in
denser environments, which indicates that these environments may
accelerate galaxy evolution. Moreover, we find higher Dn4000 values in
denser environments at fixed stellar mass, suggesting that galaxies
are on average older and/or more metal rich in these dense
environments. This set of tracers depicts a scenario where the most
massive galaxies have, on average, the lowest specic star formation
rates and the oldest stellar populations (age≳1Gyr, showing a
mass-downsizing eect). We also hypothesize that the observed increase
in star formation (higher EW[OII], higher specic star formation rate)
at intermediate densities may lead to quenching because we find that
the quenched fraction increases sharply from the lament to
cluster-like regions at similar stellar masses.
Description:
For individual spectra, the observed-frame and flux-calibrated spectra is
provided. The spectra was calibrated to the I-band magnitude of the catalog
described by Ilbert el al. (2009ApJ...690.1236I 2009ApJ...690.1236I. Cat. J/ApJ/690/1236).
The spectra is in units of erg/s/cm2/Å. For stacked spectra, the
rest-frame and normalised flux spectra is provided. Information on
which variables and bin limits were used in each stack is given in the
header of each file.
A full description of the VIS3COS survey and its sample at
Paulino-Afonso et al. (2018A&A...620A.186P 2018A&A...620A.186P).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 141 740 List of fits spectra
fits/* . 740 Individual spectra ans stacked spectra
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See also:
J/A+A/620/A186 : Properties of VIS3COS galaxies (Paulino-Afonso+, 2018)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- ID VIS3COS ID string (VIS3COS-NNN) (1)
13- 22 F10.6 deg RAdeg ? Right ascension (J2000.0) (1)
24- 31 F8.6 deg DEdeg ? Declination (J2000.0) (1)
33- 36 I4 --- Nx Number of pixels along X-axis
38- 43 F6.1 --- Ny Number of pixels along Y-axis
45- 50 F6.1 --- Nz Number of pixels along Z-axis
52- 54 F3.1 --- Nt Number of pixels along R-axis
56- 57 I2 Kibyte size Size of FITS file
59-105 A47 --- FileName Name of FITS file, in subdirectory fits
107-141 A35 --- Title Title of the FITS file
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Note (1): only for individual spectra, from Paper I,
Paulino-Afonso et al., 2018, Cat. J/A+A/620/A186.
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Acknowledgements:
Ana Paulino-Afonso, apaulinoafonso(at)tecnico.ulisboa.pt
References:
Paulino-Afonso et al., Paper I 2018A&A...620A.186P 2018A&A...620A.186P, Cat. J/A+A/620/A186
Paulino-Afonso et al., Paper II 2019A&A...630A..57P 2019A&A...630A..57P
(End) Patricia Vannier [CDS] 01-Jan-2020