J/A+A/705/A84 Galaxy size-mass relation (Liao+, 2026)
Environmental invariance of the Galaxy size-mass relation.
Liao L.-W., Cooper A.
<Astron. Astrophys. 705, A84 (2026)>
=2026A&A...705A..84L 2026A&A...705A..84L (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, masses ; Stars, diameters
Keywords: galaxies: dwarf - galaxies: formation - galaxies: statistics
Abstract:
The galaxy size-luminosity and size-stellar mass relations are
important constraints on the galactic baryon cycle of gas accretion,
star formation, and feedback. There are conflicting claims in the
literature regarding how environment influences size: both `direct'
transformative effects and `assembly bias' may contribute to observed
variations with environment.
We construct a large homogeneous sample of size measurements to
Mr~-14 (M*∼107M☉). Our sample fills a gap in field galaxy
size measurements around ∼107-108M☉; the literature at these
masses is biased towards satellites of L* galaxies and members of
galaxy clusters. We use sizes from the DESI Legacy Survey (DESI-LS;
significantly larger and deeper than SDSS), together with a published
catalog that contains stellar masses and cluster positions derived
from DESI-LS photometry. Our sample extends to z<0.3 and comprises
540228 galaxies with spectroscopic redshifts and 9513732 galaxies with
photometric redshifts. We explore the environmental dependence of size
for a mass-limited subset of our sample at z<0.05, based on distance
to the nearest cluster center.
We obtain size-luminosity and size-mass relations in good agreement
with previous studies. By separating galaxies according to color and
morphology, we show that the environmental variation of the overall
size-mass relation on megaparsec scales can be understood as the
consequence of a changing mixture of subpopulations, rather than
`direct' size transformation. For example, at fixed mass, quiescent
(red) late-type galaxies within 2Mpc of a cluster have the same size
as quiescent late-type galaxies 30Mpc from the nearest cluster. Our
results support individual galaxy assembly histories as the primary
determinant of galaxy size. The existence of significantly different,
environment-insensitive size mass relations for subpopulations
separated by color (star formation rate) and Sersic index (morphology)
provides a clear target for calibration of the baryon cycle in
cosmological simulations.
Description:
In this paper, we study the size-mass relation of galaxies at
z<0.3 using the photometric catalog from the DESI Legacy Imaging
Survey DR10. We further select a subsample of galaxies with z<0.05
and investigate the size changes in different environments, defined by
distance to the nearest cluster in the catalog of Wen & Han
(2024ApJS..272...39W 2024ApJS..272...39W, Cat. J/ApJS/272/39).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
fig4a.dat 125 11 Spectroscopic-redshift sample,
circular R50 sizes, in a given magnitude
fig4b.dat 125 11 Spectroscopic-redshift sample,
major-axis sizes, in a given magnitude
fig4c.dat 125 15 Photometric-redshift sample,
circular R50 sizes, in a given magnitude
fig4d.dat 125 15 Photometric-redshift sample,
major-axis sizes, in a given magnitude
fig5a.dat 123 14 Spectroscopic-redshift sample,
circularized half-light radii,
in a given stellar mass bin
fig5b.dat 123 14 Spectroscopic-redshift sample,
major-axis half-light radii,
in a given stellar mass bin
fig5c.dat 123 14 Photometric-redshift sample,
circularized half-light radii,
in a given stellar mass bin
fig5d.dat 123 14 Photometric-redshift sample,
major-axis half-light radii,
in a given stellar mass bin
fig11.dat 167 12 Galaxy size-mass relation measured within a
fixed 2Mpc aperture at z=0.05
--------------------------------------------------------------------------------
Byte-by-byte Description of file: fig4a.dat fig4b.dat fig4c.dat fig4d.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 A2 --- Sample [SZ PZ] Sample name (G1)
3 A1 --- --- [_]
4- 9 A6 --- Param Parameter name (G2)
11- 15 F5.1 [mag] Mbin Stellar-magnitude bin (log10(rMAG))
17- 26 F10.6 [kpc] logmuall ?=-99 Param median size for all galaxies
28- 37 F10.6 [kpc] e_logmuall ?=-99 Param 1-sigma error for all galaxies
39- 48 F10.6 [kpc] logmured ?=-99 Param median size for red subsample
50- 59 F10.6 [kpc] e_logmured ?=-99 Param 1-sigma error for red subsample
61- 70 F10.6 [kpc] logmublue ?=-99 Param median size for blue subsample
72- 81 F10.6 [kpc] e_logmublue ?=-99 Param 1-sigma error for blue subsample
83- 92 F10.6 [kpc] logmuell ?=-99 Param median size for
elliptical subsample
94-103 F10.6 [kpc] e_logmuell ?=-99 Param 1-sigma error for
elliptical subsample
105-114 F10.6 [kpc] logmuspi ?=-99 Param median size for spiral subsample
116-125 F10.6 [kpc] e_logmuspi ?=-99 Param 1-sigma error for spiral subsample
--------------------------------------------------------------------------------
Byte-by-byte Description of file: fig5a.dat fig5b.dat fig5c.dat fig5d.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 A2 --- Sample [SZ PZ] Sample name (G1)
3 A1 --- --- [_]
4- 7 A4 --- Param Parameter name (G2)
9- 13 F5.2 [Msun] sm Log10 stellar mass (bin center)
15- 24 F10.6 [kpc] logmuall ?=-99 Param median size for all galaxies
26- 35 F10.6 [kpc] e_logmuall ?=-99 Param 1-sigma error for all galaxies
37- 46 F10.6 [kpc] logmured ?=-99 Param median size for red subsample
48- 57 F10.6 [kpc] e_logmured ?=-99 Param 1-sigma error for red subsample
59- 68 F10.6 [kpc] logmublue ?=-99 Param median size for blue subsample
70- 79 F10.6 [kpc] e_logmublue ?=-99 Param 1-sigma error for blue subsample
81- 90 F10.6 [kpc] logmuell ?=-99 Param median size for
elliptical subsample
92-101 F10.6 [kpc] e_logmuell ?=-99 Param 1-sigma error for
elliptical subsample
103-112 F10.6 [kpc] logmuspi ?=-99 Param median size for spiral subsample
114-123 F10.6 [kpc] e_logmuspi ?=-99 Param 1-sigma error for spiral subsample
--------------------------------------------------------------------------------
Byte-by-byte Description of file: fig11.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 F5.2 [Msun] sm Log10 stellar mass (bin center)
7- 16 F10.6 [kpc] logmured ?=-99 Median size of red galaxies
18- 27 F10.6 [kpc] e_logmured ?=-99 1-sigma error for red galaxies
29- 38 F10.6 [kpc] logmublue ?=-99 Median size of blue galaxies
40- 49 F10.6 [kpc] e_logmublue ?=-99 1-sigma error for blue galaxies
51- 60 F10.6 [kpc] logmuell ?=-99 Median size of elliptical galaxies
62- 71 F10.6 [kpc] e_logmuell ?=-99 1-sigma error for elliptical galaxies
73- 82 F10.6 [kpc] logmuspi ?=-99 Median size of spiral galaxies
84- 93 F10.6 [kpc] e_logmuspi ?=-99 1-sigma error for spiral galaxies
95-104 F10.6 [kpc] logmuredell ?=-99 Median size of red ellipticals
106-115 F10.6 [kpc] e_logmuredell ?=-99 1-sigma error for red ellipticals
117-126 F10.6 [kpc] logmuredspi ?=-99 Median size of red spirals
128-137 F10.6 [kpc] e_logmuredspi ?=-99 1-sigma error for red spirals
139-141 I3 [kpc] logmublueell [-99] Median size of blue ellipticals
143-145 I3 [kpc] e_logmublueell [-99] 1-sigma error for blue ellipticals
147-156 F10.6 [kpc] logmubluespi ?=-99 Median size of blue spirals
158-167 F10.6 [kpc] e_logmubluespi ?=-99 1-sigma error for blue spirals
--------------------------------------------------------------------------------
Global notes:
Note (G1): Samples as follows:
SZ = spectroscopic-redshift
PZ = photometric-redshift
Note (G2): Parameters as follows:
R50 = circularized half-light radius
RMAJOR = major-axis half-light radius
--------------------------------------------------------------------------------
Acknowledgements:
Li-Wen Liao, lwliao(at)ice.csic.es
(End) Patricia Vannier [CDS] 21-Nov-2025