J/A+A/689/A28 The edges of galaxies in the Fornax Cluster (Chamba+, 2024)
he impact of environment on size:
Galaxies are 50% smaller in the Fornax Cluster compared to the field.
Chamba, N., Hayes, M., LSST Dark Energy Science Collaboration
<Astron. Astrophys. 689, A28 (2024)>
=2024A&A...689A..28C 2024A&A...689A..28C (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, optical ; Galaxies, photometry ; Photometry, SDSS
Keywords: methods: data analysis - methods: observational -
techniques: photometric - galaxies: formation -
galaxies: fundamental parameters - galaxies: photometry
Abstract:
Size is a fundamental parameter for measuring the growth of galaxies
and the role of the environment on their evolution. However, the
conventional size definitions used for this purpose are often biased
and miss the diffuse, outermost signatures of galaxy growth, including
star formation and gas accretion. We address this issue by examining
low surface brightness truncations or galaxy "edges" as a physically
motivated tracer of size based on star formation thresholds. Our total
sample consists of ∼900 galaxies with stellar masses ranging from
105M☉<M*<1011M☉. This sample of nearby cluster, group
satellite, and nearly isolated field galaxies was compiled using
multi-band imaging from the Fornax Deep Survey, deep IAC Stripe 82,
and Dark Energy Camera Legacy Surveys. We find that the edge radii
scale as Redge∝M*0.42, with a very small intrinsic scatter
(∼0.07dex). The scatter is driven by the morphology and environment of
galaxies. In both the cluster and field, early-type dwarfs are
systematically smaller by approximately 20% compared to late-type
dwarfs. However, galaxies in the Fornax cluster are the most impacted.
At a fixed stellar mass, edges in the cluster can be found at about
50% smaller radii, and the average stellar surface density at the
edges is a factor of two higher, ∼1M☉/pc2. Our findings
support the rapid removal of loosely bound neutral hydrogen (HI) in
hot, crowded environments, which truncates galaxies outside-in
earlier, preventing the formation of more extended sizes and lower
density edges. Our results highlight the importance of deep imaging
surveys to the study of low surface brightness imprints of the
large-scale structure and environment on galaxy evolution.
Description:
Physically motivated measurements are crucial for understanding galaxy
growth and the role of the environment on their evolution. In
particular, the growth of galaxies as measured by their size or radial
extent provides an empirical approach for addressing this issue.
However, the established definitions of galaxy size used for nearly a
century are ill-suited for these studies because of a previously
ignored bias. The conventionally-measured radii consistently miss the
diffuse, outer extensions of stellar emission which harbour key
signatures of galaxy growth, including star formation and gas
accretion or removal. This issue is addressed by examining low surface
brightness truncations or galaxy "edges" as a physically motivated
tracer of size based on star formation thresholds. Our total sample
consists of ∼900 galaxies with stellar masses ranging from
105M☉<M*<10^11M☉. This sample of nearby cluster, group
satellite and nearly isolated field galaxies was compiled using
multi-band imaging from the Fornax Deep Survey, deep IAC Stripe 82 and
Dark Energy Camera Legacy Survey. Across the full mass range studied,
we find that compared to the field, the edges of galaxies in the
Fornax Cluster are located at 50% smaller radii and the average
stellar surface density at the edges are two times higher. These
results are consistent with the rapid removal of loosely bound neutral
hydrogen (HI) in hot, crowded environments which truncates galaxies
outside-in earlier, preventing the formation of more extended sizes
and lower density edges. In fact, we find that galaxies with lower HI
fractions have edges with higher stellar surface density. Our results
highlight the importance of deep imaging surveys to study the low
surface brightness imprints of the large scale structure and
environment on galaxy evolution.
Edge radii and the associated surface stellar density at these
locations are provided for the 894 galaxies categorised as:
1. cluster (Venhola et al. 2019A&A...625A.143V 2019A&A...625A.143V and Su et al.
2021A&A...647A.100S 2021A&A...647A.100S, Cat. J/A+A/647/A100
using the Fornax Deep Survey (FDS))
2. satellite/group (Mao et al. 2021ApJ...907...85M 2021ApJ...907...85M for Satellites Around
Galactic Analogs (SAGA) and Carlsten et al. 2022ApJ...933...47C 2022ApJ...933...47C for
The Exploration of Local VolumE Satellites (ELVES) samples)
3. nearly isolated/field (Chamba et al. 2022A&A...667A..87C 2022A&A...667A..87C where the radii
was already available and Karachentsev et al. 2013AJ....145..101K 2013AJ....145..101K for a
sub-sample from he Updated Nearby Galaxy Catalog (UNGC)).
For each galaxy, the object name, right-ascension, declination
coordinates, Galactic extinction magnitude, distance scale used,
effective radius, derived stellar masses and global SDSS g-r colour,
sample category and survey used are included. The derivation of all
edge parameters and stellar surface density profiles accounts for
galaxy inclination using the provided axis ratios. We provide the
observed surface brightness and corrected stellar density profiles
used to make these measurements.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
sample.dat 118 894 Cluster, group and nearly isolated field sample
elvesp.dat 167 9089 Surface brightness and stellar density profiles
for galaxies selected from ELVES
sagap.dat 167 4581 Surface brightness and stellar density profiles
for galaxies selected from SAGA
ungcp.dat 167 8649 Surface brightness and stellar density profiles
for galaxies selected from UNGC
fdsdwp.dat 167 18056 Surface brightness and stellar density profiles
for the dwarf galaxies from FDS
fdseltgp.dat 167 4015 Surface brightness and stellar density profiles
for early- and late-type galaxies from FDS
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See also:
J/AJ/145/101 : UNGC (Karachentsev+, 2013)
J/A+A/623/A1 : Early-type galaxies in the Fornax Cluster (Iodice+, 2019)
J/A+A/647/A100 : Pre-processing in Fornax main cluster and group (Su+, 2021)
J/ApJ/922/267 : Structure of dwarfs in ELVES (Carsten+, 2021)
J/ApJ/907/85 : Stage II SAGA (Mao+, 2021)
J/ApJ/933/47 : The ELVES Survey (Carlsten+, 2022)
J/A+A/667/A87 : Edges of galaxies. Limits of Star Formation (Chamba+, 2022)
Byte-by-byte Description of file: sample.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- Name Name of galaxy (G1)
21- 29 F9.5 deg RAdeg Right Ascension (J2000)
31- 39 F9.5 deg DEdeg Declination (J2000)
41- 44 F4.2 mag Ag Galactic extinction in SDSS-g (1)
46- 49 F4.2 mag Ar Galactic extinction in SDSS-r (1)
51- 55 F5.3 kpc/arcsec scale Physical distance-to-arcsec scale (G2)
57- 60 F4.2 --- q Axis ratio
62- 68 F7.2 deg PA [] Position angle (G3)
70- 74 F5.2 [Msun] logMstar Log10 of stellar mass (2)
76- 80 F5.2 kpc Re Effective/half-light radius (3)
82- 86 F5.2 mag g-r ? SDSS-g minus SDSS-r global colour (4)
88- 92 F5.2 kpc Redge Edge radius (5)
94- 97 F4.2 Msun/pc2 Sigmaedge Surface stellar density at the edge (2)
99-103 A5 --- Sample C22, SAGA, ELVES, UNGC or FDS (6)
105-111 A7 --- Class cluster, group or field
113-118 A6 --- Survey IACS82, DECaLs or FDS (7)
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Note (1): Galactic extinction values were obtained using the NED calculator
(https://ned.ipac.caltech.edu/forms/calculator.html) by specifying
(RAdeg, DEdeg).
Note (2): Stellar surface densities and masses were computed using
mass-to-light ratio and g-r colour relations from Roediger & Courteau
(2015MNRAS.452.3209R 2015MNRAS.452.3209R).
Note (3): The radius enclosing half the total light using the SDSS-g band.
The total light is computed by creating a flux growth curve of the galaxy
until the surface brightness limit of the image is reached.
Note (4): Global colours are corrected for Galactic extinction using the values
provided.
Note (5): See Chamba et al. (2022A&A...667A..87C 2022A&A...667A..87C. Cat. J/A+A/667/A87) for
edge identification procedure and criteria.
Note (6): C22 for Chamba et al. (Cat. J/A+A/667/A87).
Note (7): All surveys and images are public. The sample selection depended on
SDSS-g and SDSS-r band image availability from these surveys as their
quality is similar (PSF FWHM ∼ 1'').
DECaLs (Day et al. 2019AJ....157..168D 2019AJ....157..168D) imaging is ∼1mag shallower than
IACS82 (Roman et al. 2018RNAAS...2..144R 2018RNAAS...2..144R) but sufficient to detect edges.
FDS (Peletier et al. 2020arXiv200812633P 2020arXiv200812633P) is our deepest dataset by
∼1mag compared to IACS82.
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Byte-by-byte Description of file: *p.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- Name Name of galaxy (G1)
22- 35 F14.11 kpc Dist Distance from galaxy centre (G4)
38- 46 F9.6 mag/arcsec2 SBg Observed surface brightness in SDSS-g (G5)
50- 61 E12.10 mag/arcsec2 e_SBg Lower error bar of SBg (G6)
65- 76 E12.10 mag/arcsec2 E_SBg ?=- Upper error bar of SBg (G6)
80- 88 F9.6 mag/arcsec2 SBr Observed surface brightness in SDSS-r (G5)
92-103 E12.10 mag/arcsec2 e_SBr Lower error bar of SBr (G6)
107-118 E12.10 mag/arcsec2 E_SBr ?=- Upper error bar of SBr (G6)
122-138 F17.13 Msun/pc2 logSD Log10 of stellar surface density
140-152 F13.10 Msun/pc2 e_logSD Lower error bar of logSD (G7)
155-167 F13.10 Msun/pc2 E_logSD ?=- Upper error bar of logSD (G7)
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Global notes:
Note (G1): Names of galaxies are as those used in the cited catalogs per sample.
Note (G2): The distances using to calculate the kpc-arcsec scale are also taken
from the sample catalogs. For ELVES specifically, we ranked the distances
according to availability and in order of preference for those derived using
the: TGRB, recession velocity and surface brightness fluctuations method.
Note (G3): PA was measured counter-clockwise w.r.t the positive x-axis.
Note (G4): The centre of each elliptical bin (semi-major axis) used to average
the flux in kpc (see paper for details). The profiles are provided up to
1.5 times Redge.
Note (G5): The profile provided is background corrected.
Use SB - A - 10log10(1+z) for the additional Galactic extinction and dimming
corrections used in the publication. z (the redshift) is obtained using the
adopted distance for a flat cosmology with H0 = 70.4 and omega = 0.3.
See Trujillo et al. (2020MNRAS.493...87T 2020MNRAS.493...87T, Cat. J/MNRAS/493/87) for the
separate formula used for inclination corrections.
Note (G6): The error bars were computed by quadratically summing the standard
uncertainties from (a) averaging flux in elliptical annuli and
(b) the background subtraction.
We provide lower and upper error bars as they are non-symmetric along the
y-axis.
Note (G7): Computed using the uncertainties in surface brightness.
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Acknowledgements:
Nushkia Chamba, nushkia.chamba(at)nasa(dot)gov,
Stockholm University/NASA Ames Research Center
(End) Nushkia Chamba [Stockholm Univ.], Patricia Vannier [CDS] 17-Dec-2023