J/MNRAS/520/5870 Remnant merger structures of ETGs with SDSS (Giri+, 2023)
Remnants of recent mergers in nearby early-type galaxies and their
classification.
Giri G., Barway S., Raychaudhury S.
<Mon. Not. R. Astron. Soc. 520, 5870-5884 (2023)>
=2023MNRAS.520.5870G 2023MNRAS.520.5870G (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies ; Galaxies, interacting ; Morphology ; Photometry ;
Optical ; Positional data
Keywords: galaxies: elliptical and lenticular, cD - galaxies: evolution -
galaxies: interactions - galaxies: peculiar - galaxies: structure
Abstract:
We search for signatures of recent galaxy close interactions and
mergers in a sample of 202 early-type galaxies in the local universe
from the public SDSS Stripe82 deep images
(µr ∼ 28.5 mag arcsec-2). Using two different methods to remove
galaxies' smooth and symmetric light distribution, we identify and
characterize 11 distinct types of merger remnants embedded in the
diffuse light of these early-type galaxies. We discuss how the
morphology of merger remnants can result from different kinds of minor
and major mergers, and estimate the fraction of early-type galaxies in
the local universe with evidence of recent major (27 per cent) and
minor (57 per cent) mergers. The merger fractions deduced are higher
than in several earlier surveys. Among remnants, we find that shells
are the dominant merger debris (54 per cent) associated with
early-type galaxies, resulting from both major and minor mergers, with
those characteristics of major mergers being significant (24 per cent
of shell host galaxies). The most uncommon merger-related structures
are boxy isophotes of the stellar distribution and the presence of
disc fragments near the cores of galaxies. We develop a classification
scheme for these fine structures that may be used to infer their
likely genesis histories. The classification is primarily based on the
mass ratios of the merged galaxies. This work, when combined with
predictions from numerical simulations, indicates that most (if not
all) early-type galaxies in the local Universe are continually
evolving as a result of (minor) merger activities.
Description:
In this work, we search for low-surface brightness features in a
sample of ETGs. For this purpose, we make use of the deep imaging in
the SDSS Stripe82 (S82) from the IAC Stripe82 legacy project (Fliri &
Trujillo 2016MNRAS.456.1359F 2016MNRAS.456.1359F, Cat. J/MNRAS/456/1359). The S82 is a
region of the skycovering 275 degree2 The IAC Stripe82 legacy
project provides deep images, co-adding multi-epoch observations to
reach very faint surface brightness limits (3σ limits of 28.5
per arcsec2) in the r-band. To obtain morphological information for
the galaxies found in the S82 deep images, we have used the Galaxy Zoo
2 Strip82 co-added depth catalogues (Willett et al.
2013MNRAS.435.2835W 2013MNRAS.435.2835W, Cat. J/MNRAS/435/2835), which provide visual
morphology for ∼39530 galaxies and classify them into elliptical and
spiral morphological types. We then select only the galaxies
classified as ellipticalo obtain parameters such as position,
Petrosian radius, and redshift of these galaxies, we used the table
SDSS metadata for GZ2. We applied a cut-off in redshift z ≤ 0.05 to
retain only the nearby early-types. In order to search for low
brightness features, we select galaxies with large enough angular
extent by putting another cut in Petrosian radius, i.e.
Rp90 => 10arcsec. This gives us a sample of 566 ETGs, which we use
for this study. We have also used a sample of 55 bright elliptical
galaxies taken from the OBEY survey (Observations of Bright
Ellipticals at Yale) as a control sample (Tal et al.
2009AJ....138.1417T 2009AJ....138.1417T). We use this sample to check the compatibility of
the techniques used in this study. All science image are available in
archival r-band data of IAC Stripe 82 Legacy Project
(http://research.iac.es/proyecto/stripe82/) and for the 55 bright
elliptical galaxies taken from the OBEY survey
(http://www.astro.yale.edu/obey/index.html), (see section 2 and
Introduction for more details).
As exposed in section 3, in images, we find irregular galaxies and
edge-on-disc galaxies that are misclassified as ETGs. We exclude such
galaxies from our subsequent analysis, reducing our sample to 202
galaxies classified as elliptical by Galaxy Zoo 2 and showing no sign
of large-scale spiral features in the residual images. Next, we
identified merger structures associated to ETGs by visual inspection
as highlighted in section 4 figures. We releaved eleven types of
merger structures, we now focus on merger remnants ones to construct a
a classification scheme of these as explained in section 5 figure 9.
We have prepared a 'Merger Catalogue of Early-type Galaxies' as shown
in table3.dat for our 202 ETGs.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 144 202 Merger Catalogue of Early-type Galaxies with
z≤0.05 and petrosian radius RP90=>10"
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See also:
J/MNRAS/499/3399 : Long tidal tails in merging galaxies (Ren+, 2020)
J/MNRAS/471/4027 : CVRHS classifications for the GZ2 Ring Sample (Buta, 2017)
J/MNRAS/456/1359 : IAC Stripe 82 Legacy Project: Photometry (Fliri+, 2016)
J/MNRAS/446/120 : ATLAS3D project. XXIX (Duc+, 2015)
J/MNRAS/435/2835 : Morphological types from Galaxy Zoo 2 (Willett+, 2013)
J/MNRAS/416/1680 : ATLAS3D project. VII. (Cappellari+, 2011)
J/MNRAS/406/382 : Early-type galaxies in the SDSS Stripe82 (Kaviraj, 2010)
J/ApJ/857/144 : Tidal features from RESOLVE survey & DECaLS images
(Hood+, 2018)
J/ApJ/697/1369 : GOODS Ks-selected multiwavelength compilations (Bundy+,2009)
J/ApJ/685/235 : Host and companion galaxies in the SDSS (Patton+, 2008)
J/A+A/640/A38 : gr images of 20 isolated early-type galaxies
(Rampazzo+, 2020)
J/A+A/631/A87 : Close pairs of galaxies in MUSE Deep Fields (Ventou+, 2019)
J/A+A/602/A100 : Merging groups and clusters from the SDSS data
(Tempel+, 2017)
J/A+A/597/A134 : Kohonen selected E+A galaxies from SDSS DR7
(Meusinger+, 2017)
J/ApJ/565/208 : Galaxy pairs in the CNOC2 Redshift Survey (Patton+, 2002)
J/ApJS/217/32 : S4G galaxy morphologies in the CVRHS system (Buta+, 2015)
J/ApJS/186/427 : Detailed morphology of SDSS galaxies (Nair+, 2010)
J/ApJS/181/572 : Collisional ring galaxies atlas (Madore+, 2009)
J/AJ/134/579 : Morphologically classified galaxies from SDSS DR3
(Fukugita+, 2007)
J/AJ/129/2138 : Centers of early-type galaxies with HST (Lauer+, 2005)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 24 A24 --- SDSS Early-type galaxy SDSS names as SDSS
JHHMMSS.ss+DDMMSS.s (SDSS_name)
26- 36 F11.7 deg RAdeg Right ascension (J2000)
38- 47 F10.7 deg DEdeg Declination (J2000)
49- 54 A6 --- Struc Merger structure characteristic from type of
structure as proposed in the classification
scheme discussed (Structure) (1)
56- 60 A5 --- FileName The linked file name of the merger (File_name)
62-144 A83 --- n_Struc The corresponded work comment on morphologies
and structures (Comments)
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Note (1): For example, if one galaxy reveals an underlying structure
corresponding to a collisional ring, we attach the label 'mb'.
Similarly, suppose a shell appears in a galaxy, in that case, we
will label it with 'mb' or 'mi' ('mb/mi') or 'Ml', depending on
the structure's properties. As fully explicited in section 4, we
have identified merger structures by visual inspection, given that
automated processes can have issues which raise misleading results.
The full labels list is Mh, Ml, R, mb, mb/mi, mi, mi/ms, ms.
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History:
From electronic version of the journal
License: CC-BY-4.0 [see https://spdx.org/licenses/]
(End) Luc Trabelsi [CDS] 17-Apr-2026