J/A+A/666/A131 Galaxy subtypes in the VIPERS survey (Siudek+, 2022)
Shaping physical properties of galaxy subtypes in the VIPERS survey:
environment matters.
Siudek M., Malek K., Pollo A., Iovino A., Haines C.P., Bolzonella M.,
Cucciati O., Gargiulo A., Granett B., Krywult J., Moutard T., Scodeggio M.
<Astron. Astrophys. 666, A131 (2022)>
=2022A&A...666A.131S 2022A&A...666A.131S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxy catalogs ; Photometry, classification
Keywords: galaxies: evolution - galaxies: stellar content -
galaxies: groups: general
Abstract:
This study aims to explore the relation between the physical
properties of different galaxy subclasses, from red passive to
blue star-forming, and their environment. Our work is based on the
analysis of 31 631 VIMOS Public Extragalactic Redshift Survey (VIPERS)
galaxies observed at 0.5<z<0.9. The unprecedented volume of VIPERS
and the wealth of auxiliary derived data allow us to associate
subclasses of the main galaxy populations with their possibly
different evolutionary paths. Such a study is performed for the first
time with such statistical precision.
We use the results of an unsupervised clustering algorithm to
distinguish 11 subclasses of VIPERS galaxies based on the
multi-dimensional feature space defined by rest-frame UV to NIR
colours presented in Siudek et al. (2018A&A...617A..70S 2018A&A...617A..70S). We
investigate the relationship between the properties of these
subclasses of galaxies and their local environment, defined as the
galaxy density contrast, δ, derived from the 5th nearest
neighbour technique.
We confirm that the galaxy population-density relation is already in
place at z∼0.9, with the blue galaxy fraction decreasing with
density, compensated by an increase of the red fraction. We
demonstrate how the properties of red, green, and blue galaxy
subclasses are altered as they assemble into denser regions and we
attempt to interpret it in the context of their evolution. On average
red galaxies in the high-density environment are larger by 28% than
the ones in low-density environments. In particular, we find one group
of galaxies, subclass C3, whose increase of size with time can be
explained mainly as the result of mergers; for other red subclasses,
mergers would not seem to play the major role (subclass C2) or play a
negligible role (subclass C1). The properties of the green galaxies
(subclasses C4-6) depend on whether their stellar mass is above or
below a transition mass, log(Mstar/M☉)=10.6. Low-mass green
(9.5≲log(Mstar/M☉)≲10.6) galaxies appear to have grown through
secular processes, while in high-mass (10.6≲log(Mstar/M☉)≲11.5)
green galaxies mass assembly appears to be dominated by mergers. When
it comes to blue galaxies, the trend of decreasing fraction with
denser environments seen for the group as a whole (subclasses C7-11)
is found to be driven mostly by one (the most numerous) group of
galaxies, subclass C10. These are compact low-mass galaxies with high
specific star formation rates, that are preferentially found in
low-density environments. However, the remaining blue galaxies
(subclasses C7-9) are larger and appear in denser environments than
galaxies within C10.
Description:
We analyse the relations between the physical properties of
galaxy (sub)classes and their local density contrast δ, based on
a sample of 31631 VIPERS galaxies observed over redshift range
0.5<z<0.9.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
class.dat 39 31631 Catalog of the galaxies with their class
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See also:
J/A+A/562/A23 : VIMOS Public Extragalactic Survey (VIPERS) DR1 (Garilli+, 2014)
http://vipers.inaf.it/ : VIPERS Home Page
Byte-by-byte Description of file: class.dat
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Bytes Format Units Label Explanations
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1- 9 I9 --- VIPERS VIPERS identification number
(Scodeggio et al. 2018A&A...609A..84S 2018A&A...609A..84S)
11- 19 F9.5 deg RAdeg Right ascension (J2000)
21- 29 F9.5 deg DEdeg Declination (J2000)
31- 36 F6.4 --- zspec Spectroscopic redshift
38- 39 I2 --- Class [1/11] VIPERS galaxy class assigned with
unsupervised machine-learning technique by
Siudek et al. 2018A&A...617A..70S 2018A&A...617A..70S (1)
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Note (1): red (1-3), green (4-6) and blue (7-11) galaxy classes.
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Acknowledgements:
Malgorzata Siudek, malgorzata.siudek(at)gmail.com
(End) Patricia Vannier [CDS] 31-May-2022