J/MNRAS/520/L85 HSC gLSB galaxies structures and SB properties (Saburova+, 2023)
The volume density of giant low surface brightness galaxies.
Saburova A.S., Chilingarian I.V., Kulier A., Galaz G., Grishin K.A.,
Kasparova A.V., Toptun V., Katkov I.Y.
<Mon. Not. R. Astron. Soc. 520, L85-90 (2023)>
=2023MNRAS.520L..85S 2023MNRAS.520L..85S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies ; Galaxies, ring ; Redshifts ; Morphology ; Photometry ;
Optical ; X-ray sources ; Active gal. nuclei ; Galaxies, radius ;
Magnitudes, absolute
Keywords: galaxies: evolution - galaxies: formation -
galaxies: kinematics and dynamics - galaxies: spiral
galaxies: photometry
Abstract:
Rare giant low surface brightness galaxies (gLSBGs) act as a stress
test for the current galaxy formation paradigm. To answer the question
'How rare are they?', we estimate their volume density in the local
Universe. A visual inspection of 120 deg2 covered by deep Subaru
Hyper Suprime-Cam data was performed independently by four team
members. We detected 42 giant disky systems (30 of them isolated) at
z ≤ 0.1 with either g-band 27.7 mag arcsec-2 isophotal radius or
four disc scale lengths 4h => 50 kpc, 37 of which (including 25
isolated) had low central surface brightness
(µ0,g => 22.7 mag arcsec-2). This corresponds to volume
densities of 4.70*10-5 Mpc-3 for all galaxies with giant extended
discs and 4.04*10-5Mpc-3 for gLSBGs, which converts to ∼12700 such
galaxies in the entire sky out to z < 0.1. These estimates agree well
with the result of the Evolution and Assembly of GaLaxies and their
Environments (EAGLE) cosmological hydrodynamical simulation. Giant
disky galaxies represent the large-sized end of the volume density
distribution of normal-sized spirals, suggesting the non-exceptional
nature of giant discs. We observe a high active galactic nucleus
fraction among the newly found gLSBGs.
Description:
Giant low surface brightness galaxies (gLSBGs) are rare objects with a
low surface brightness (LSB) disc (the central B-band disc surface
brightness µ0 > 22 mag.arcsec-2) and radii up to 130 kpc,
dynamical and stellar masses of the order of 1012 and 1011
M☉, respectively. These enormous regularly rotating stellar
systems act as a stress test for the currently considered scenarios of
galaxy formation: in the reference EAGLE cosmological hydrodynamical
simulation. Deep images obtained with the 8-m Subaru telescope Hyper
Suprime-Cam HSC present the best opportunity to search for gLSBGs in a
large area of the sky and study their structure. Due to the low number
of known gLSBGs in the HSC footprint, their automatic search, with
e.g. artificial neural networks, is impossible because the training
set is too small. Therefore, we decided to undertake a visual search
for gLSBGs using HSC data by several team members to minimize the
subjectivity of the selection. Our ultimate goal is to estimate the
volume density of gLSBGs with disc radii rd => 50 kpc and compare it
to the value derived from cosmological hydrodynamical simulations,
(i.e. see Introduction section). We chose a 120 deg2 patch of the
HSC-SSP DR2 survey (images are available on DESI Legacy Survey
website) (28° < RA < 40°, -7° < Dec. < 3°), which
contains one historically known gLSBG (UGC 1382) and is relatively
compact in the sky so that we can neglect the variations of the
Galactic foreground extinction across the area. We looked available
redshifts in NED, SIMBAD and RCSED of Chilingarian et al.
(2017ApJS..228...14C 2017ApJS..228...14C) and retained the objects with visual radii
r > 40 kpc. For statistical analysis, we restrain our sample to z < 0.1.
Each of the four team members performed the search independently, then
the lists of candidates were compared and merged. For photometry
extractions we used ELLIPSE task in the python photutils library (see
section 2).
The isophotal analysis revealed 52 galaxies having riso,28B > 50 kpc.
The radii obtained from the analysis exceed those estimated by eye by
our team members by 10-24 per cent. The next step was to derive the
disc scale length (h) and the central surface brightness (µ0) for
each object, because some of the 52 galaxies resembled oversized
'normal' HSB spirals. We assumed that the radial light profiles in the
surface brightness range µg = 27.6 to 25.1 mag are adequately
described by a single exponential profile, which then yields both h
and µ0 by extrapolation to the galaxy centre. This surface
brightness range was chosen iteratively by visual inspection of the
light profiles to find the best compromise between the effects of
noise and background subtraction on the low end and the complexity of
galaxy structure (e.g. spiral arms, H II regions) affecting the
brighter end. Since the galaxies have different inclination angles, we
deprojected the surface brightness profiles using a simple geometric
assumption for the thin disc without internal extinction, which is
model dependent. We used the ellipticity from the isophotal 25th
g-band isophote. The correction led to the decrease of the isophotal
radii in the more inclined galaxies. In some cases, the galaxies came
outside the limit riso,28B > 50 kpc. Some of the outliers still
appeared to have giant discs if we used the alternative disc radius
definition rD = 4h which is more suitable for LSB galaxies. Thus, we
decided to use the milder restriction rD => 50 kpc or
riso,28B => 50 kpc to form the final sample of giant disky galaxies,
and came up with 42 galaxies. Among them we found 27 galaxies that
satisfy both criteria and 37 galaxies with the outer discs having
deprojected µ0,g > 22.7 mag.arcsec-2, which corresponds to
µ0,B > 23.0 mag.arcsec-2. All 37 LSB galaxies have disc radii
rD => 50 kpc. The area corresponds to a volume of 9.2 * 105 Mpc3
and a volume density of (4.7 ± 0.64) * 10-5 Mpc-3 for all the
galaxies (rD => 50 kpc or riso,28B => 50 kpc) and
(4.7 ± 0.64) * 10-5 Mpc-3 for gLSBGs (see section 3).
For the 42 galaxies, we present in table1.dat the coordinates,
redshifts, structural properties (morphological types, scales, b/a
axis ratio, isophote radius R and rD), g-r colour and g-band
absolute magnitude from Abbott et al. (2018ApJS..239...18A 2018ApJS..239...18A,
Cat. II/357), notes (as on AGN/SF types, catalog names for spectral
data and environments of the galaxy from visual inspection as seen in
section 3.4) and finally retreived X-ray luminosities from XMM, SWIFT
and ROSAT catalogs as seen in section 3.3. Our results are compared to
cosmological hydrodynamical simulations in section 3.2.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 200 42 Astrometrics, redshifts, structural properties
of the giant disc galaxies discovered in the HSC
imaging data by visual inspection
appen.pdf 512 29913 Appendix images of the 42 galaxies
--------------------------------------------------------------------------------
See also:
J/MNRAS/489/4669 : UGC 1378's giant low surface brightness disc
(Saburova+, 2019)
J/MNRAS/410/166 : Morphological types from Galaxy Zoo 1 (Lintott+, 2011)
J/A+A/651/L15 : Angular-momentum plane for disc galaxies
(Mancera Pina+, 2021)
J/A+A/631/A87 : Close pairs of galaxies in MUSE Deep Fields (Ventou+, 2019)
J/A+A/618/A81 : Bayesian group finder applied to the 2MRS data
(Tempel+, 2018)
J/A+A/596/A14 : Group catalogues of the local universe (Saulder+, 2016)
J/A+A/593/A126 : Malin 1 images at 6 wavelengths (Boissier+, 2016)
J/ApJ/861/49 : ALFALFA extragalactic HI source catalog (Haynes+, 2018)
J/ApJS/228/14 : Short Title (Chilingarian+, 2017)
J/ApJS/196/11 : Bulge+disk decompositions of SDSS galaxies (Simard+, 2011)
J/AJ/149/171 : 2MASS galaxy group catalog (Tully, 2015)
J/AJ/130/873 : Properties of BQS objects in the SDSS DR3 area
(Jester+, 2005)
VIII/89 : Northern HI Parkes All Sky Survey Catalogue (HIPASS)
(Wong+, 2006)
II/357 : The Dark Energy Survey (DES): Data Release 1
(Abbott+, 2018)
IX/63 : XMM-Newton Serendipitous Source Catalogue 4XMM-DR10
(Webb+, 2022)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 25 A25 --- Galaxy Name of the galaxy (Galaxy)
27- 34 F8.5 deg RAdeg Right ascension (J2000) (RA)
36- 43 F8.5 deg DEdeg Declination (J2000) (Dec)
45- 49 F5.3 --- z The redshift (z)
51- 54 A4 --- Type The morphological type (Type)
56- 59 F4.2 kpc/arcsec Scale The scale (Scale)
61- 62 I2 kpc R The radius of 27.7 g-band isophote
(Rg=27.7)
64- 68 F5.2 mag/arcsec+2 mu The g-band central surface brightness of
exponential disc (mu0,g)
70- 71 I2 kpc 4H The 4 exponental disc scale-lengths (4h)
73- 76 F4.2 mag g-r ? Total g-r colour index (g-r)
78- 83 F6.2 mag gMag ? The g-band absolute magnitude (Mg)
85- 88 F4.2 --- b/a The ratio of semi-minor to semi-major
axis for 25 g-band isophote (b/a)
90- 99 A10 --- BPT Note on AGN and SF types (BPT)
101-109 A9 --- Spec Note on availability of spectral data
(Spec)
111 A1 --- l_LX Upper limit flag on LX
113-121 F9.3 10+33W LX X-ray luminosity soft-medium from 0.2keV
to 10 keV (LX)
123-129 F7.3 10+33W e_LX ? Uncertainty on LX (LX)
131-135 A5 --- r_LX Literature reference of LX (1)
137-200 A64 --- Env Note on environment of the galaxy
(Environment)
--------------------------------------------------------------------------------
Note (1): Literature reference are as follows:
ROSAT = All ROSAT catalogs presented in nasa's HEASARC website
(https://heasarc.gsfc.nasa.gov/docs/heasarc/biblio/pubs/
rosat_ycat.html), 11 sources in our sample
SWIFT = SWIFT 2SXPS from Evans et al. 2020ApJS..247...54E 2020ApJS..247...54E,
Cat. IX/58, 4 sources in our sample
XMM = 4XMM-DR10 from Webb et al. 2020A&A...641A.136W 2020A&A...641A.136W, Cat. IX/63,
27 sources in our sample
--------------------------------------------------------------------------------
History:
From electronic version of the journal
License: CC-BY-4.0
(End) Luc Trabelsi [CDS] 27-Apr-2026