J/A+A/608/A142 Fornax Deep Survey with VST. III. LSB galaxies (Venhola+, 2017)
The Fornax Deep Survey with VST.
III. Low surface brightness dwarfs and ultra diffuse galaxies in the center
of the Fornax cluster.
Venhola A., Peletier R., Laurikainen E., Salo H., Lisker T., Iodice E.,
Capaccioli M., Kleijn G.V., Valentijn E., Mieske S., Hilker M.,
Wittmann C., van de Ven G., Grado A., Spavone M., Cantiello M.,
Napolitano N., Paolillo M., Falcon-Barroso J.
<Astron. Astrophys., 608, A142 (2017)>
=2017A&A...608A.142V 2017A&A...608A.142V (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Galaxies, photometry ; Morphology
Keywords: galaxies: dwarf - galaxies: photometry - galaxies: evolution -
galaxies: clusters: individual: Fornax
Abstract:
Studies of low surface brightness (LSB) galaxies in nearby clusters
have revealed a sub-population of extremely diffuse galaxies with
central surface brightness of µ0,g'>24mag/arcsec2, total
luminosity Mg' fainter than -16mag and effective radius between
1.5kpc<Re<10kpc. The origin of these ultra diffuse galaxies (UDGs)
is still unclear, although several theories have been suggested. As
the UDGs overlap with the dwarf-sized galaxies in their luminosities,
it is important to compare their properties in the same environment.
If a continuum is found between the properties of UDGs and the rest of
the LSB population, it would be consistent with the idea that they
have a common origin.
Our aim is to exploit the deep g', r' and i'-band images of the Fornax
Deep Survey (FDS), in order to identify LSB galaxies in an area of
4deg2 in the center of the Fornax cluster. The identified galaxies
are divided into UDGs and dwarf-sized LSB galaxies, and their
properties are compared.
We identified visually all extended structures having r'-band central
surface brightness of µ0,r'>23mag/arcsec2. We classified the
objects based on their appearance into galaxies and tidal structures,
and perform 2D Sersic model fitting with GALFIT to measure the
properties of those classified as galaxies. We analyzed their radial
distribution and orientations with respect of the cluster center, and
with respect to the other galaxies in our sample. We also studied
their colors and compare the LSB galaxies in Fornax with those in
other environments.
Our final sample complete in the parameter space of the previously
known UDGs, consists of 205 galaxies of which 196 are LSB dwarfs (with
Re<1.5kpc) and nine are UDGs (Re>1.5kpc). We show that the UDGs
have (1) g'-r' colors similar to those of LSB dwarfs of the same
luminosity; (2) the largest UDGs (Re>3kpc) in our sample appear
different from the other LSB galaxies, in that they are significantly
more elongated and extended; whereas (3) the smaller UDGs differ from
the LSB dwarfs only by having slightly larger effective radii; (4) we
do not find clear differences between the structural parameters of the
UDGs in our sample and those of UDGs in other galaxy environments; (5)
we find that the dwarf LSB galaxies in our sample are less
concentrated in the cluster center than the galaxies with higher
surface brightness, and that their number density drops within 180 kpc
from the cluster center. We also compare the LSB dwarfs in Fornax with
the LSB dwarfs in the Centaurus group, where data of similar quality
to ours is available. (6) We find the smallest LSB dwarfs to have
similar colors, sizes and Sersic profiles regardless of their
environment. However, in the Centaurus group the colors become bluer
with increasing galaxy magnitudes, an effect which is probably due to
smaller mass and hence weaker environmental influence of the Centaurus
group.
Our findings are consistent with the small UDGs forming the tail of a
continuous distribution of less extended LSB galaxies. However, the
elongated and distorted shapes of the large UDGs could imply that they
are tidally disturbed galaxies. Due to limitations of the automatic
detection methods and uncertainty in the classification the objects,
it is yet unclear what is the total contribution of the tidally
disrupted galaxies in the UDG population.
Description:
We use the ongoing Fornax Deep Survey (FDS), which consists of the
combined data of the Guaranteed Time Observation Surveys FOCUS (P.I.
R. Peletier) and VEGAS (P.I. E. Iodice), dedicated to the Fornax
cluster. Both surveys are performed with the ESO VLT Survey Telescope
(VST), which is a 2.6-m diameter optical telescope located at Cerro
Paranal, Chile. The imaging is done with the OmegaCAM instrument,
using the u', g', r' and i'-bands, and 1°x1° field of view.
The observations used in this work were gathered in visitor mode runs
during November 2013, 2014 and 2015 (ESO P92, P94 and P96,
respectively). All the observations were performed in clear
(photometric variations <10%) or photometric conditions. The
observations in u' and g'-bands were obtained in dark time, and
those of the other bands in gray or dark time.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tabled1.dat 99 205 Parameters of the LSB galaxies in our sample
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See also:
J/A+A/623/A1 : Fornax Deep Survey with VST. V. Isophote fit (Iodice+, 2019)
Byte-by-byte Description of file: tabled1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Name of the object (FDSNN_LSBNN)
12 A1 --- n_Name [*] Note on Name (1)
14- 19 F6.3 deg RAdeg Right ascension (J2000)
21- 27 F7.3 deg DEdeg Declination (J2000)
29- 32 F4.2 --- b/a Axial ratio
34- 37 F4.2 --- e_b/a rms uncertainty on b/a
39- 44 F6.2 deg theta Position angle (east of north)
46- 50 F5.2 mag r'mag Sloan r' magnitude
52- 55 F4.2 mag e_r'mag rms uncertainty on r'mag (2)
57- 61 F5.1 arcsec Re Effective radius in r'-band
63- 66 F4.1 arcsec e_Re rms uncertainty on Re (2)
68- 71 F4.2 --- n Sersic index
73- 76 F4.2 --- e_n rms uncertainty on n (2)
78- 81 F4.2 mag g'-r' Sloan g'-r' colour index
83- 86 F4.2 mag e_g'-r' rms uncertainty on g'-r' (2)
88- 93 A6 --- FCC Possible FCC number (Cat. VII/180)
95- 99 A5 --- Ref Identifications in earlier works (3)
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Note (1): * indicates that it was fit using a additional PSF component for
the nucleus.
Note (2): The error estimations for each parameter are adopted from the tests
made with the mock galaxies in Sect. 5.4.2.
Note (3): References as follows:
a = Ferguson (1989AJ.....98..367F 1989AJ.....98..367F, Cat. VII/180)
b = Bothun et al. (1991ApJ...376..404B 1991ApJ...376..404B)
c = Munoz et al. (2015, Cat. J/ApJ/813/L15)
d = Mieske et al. (2007, Cat. J/A+A/463/503)
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History:
From electronic version of the journal
References:
Iodice et al., Paper I 2016ApJ...820...42I 2016ApJ...820...42I
Iodice et al., Paper II 2017ApJ...839...21I 2017ApJ...839...21I
Venhola et al., Paper IV 2018A&A...620A.165V 2018A&A...620A.165V
Iodice et al., Paper V 2019A&A...623A...1I 2019A&A...623A...1I, Cat. J/A+A/623/A1
(End) Patricia Vannier [CDS] 20-Feb-2018