J/A+A/706/A89 BP/X-shaped bulge galaxies with GalaxyZoo/SDSS (Samanta+, 2026)
Bar evolution in edge-on galaxies A demographic study of boxy/peanut bulges.
Samanta A.A., Kumar A., Das M., Artale M.C.
<Astron. Astrophys. 706, A89 (2026)>
=2026A&A...706A..89S 2026A&A...706A..89S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies ; Morphology ; Photometry, SDSS; Optical ; Infrared
Keywords: galaxies: bulges - galaxies: evolution - galaxies: formation -
galaxies: general
Abstract:
Boxy/peanut and X-shaped (BP/X) bulges are prominent features in
edge-on disk galaxies and are believed to be vertically thickened
bars. Despite their relevance in bar evolution, a statistically robust
census of these structures in large surveys has been lacking.
We aim to provide the largest catalog of BP/X structures in edge-on
galaxies to date, and to investigate their properties and role in
shaping galaxy scaling relations. Methods. We selected a sample of
6684 edge-on galaxies from SDSS DR8 using Galaxy Zoo classifications,
requiring a high edge-on probability (>0.9) and a minimum of 10
independent votes. Two-dimensional image decomposition is performed
using GALFIT to obtain structural parameters. Residual images are
visually inspected to classify BP/X features into four categories:
strong both-sided, both-sided, one-sided, and control (no BP/X). We
also estimate stellar mass, distance, and physical size for each
galaxy.
Out of 6653 classified galaxies, we identified 1673 (∼25%) with
both-sided BP/X features-504 (∼8%) strong and 1169 (∼17%) weak-as well
as 1112 (∼17%) one-sided structures, making up a total of 2785
BP/X-hosting galaxies (∼42%). One-sided structures, likely signatures
of ongoing buckling, are more frequent than strong both-sided bulges
across all stellar masses. The fraction of BP/X bulges increases with
stellar surface mass density, indicating a connection with bar
formation in dense disks. We also find that galaxies with strong BP/X
bulges contribute to increased scatter in the stellar mass-size and
stellar mass-surface density relations, particularly at higher masses.
Description:
Various physical parameters are provided for the galaxies along with
their observational identities like SDSS Object ID, RA, DEC, RUN,
RERUN, CAMCOL, FIELD. The mass and distance is reported along with the
edge-on disk profile fitting parameters. The bulge type is mentioned
in the column 'BPX'. It is classified as 'control': No BP/X, 'ones':
One-sided BP/X, 'bpx-': Weak BP/X and 'bpx+': Strong BP/X. The first
19 columns (6-182 Bytes) are obtained from the SDSS catalog and used
in the calculation of other parameters. Results are presented in
catalog.dat.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 343 6653 Photometry, physical and visual properties
our galaxies with and without BP/X bulges
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See also:
J/A+A/644/A38 : Halpha images of stellar bars in galaxies
(Diaz-Garcia+, 2020)
J/A+A/587/A160 : 3.6um S4G Galactic bars characterization (Diaz-Garcia+,2016)
J/A+A/445/765 : A Catalog of Edge-on Disk Galaxies (Kautsch+, 2006)
J/A+AS/145/405 : Box- and peanut-shaped bulges. I. (Luetticke+, 2000)
J/ApJ/845/87 : CGS. V. Statistical study of bars and buckled bars
(Li+, 2017)
J/ApJS/196/11 : Bulge+disk decompositions of SDSS galaxies (Simard+, 2011)
J/MNRAS/495/4158 : Star formation in barred galaxies (Fraser-McKelvie+, 2020)
J/MNRAS/468/2058 : Boxy/peanut-shaped bulges in barred galaxies (Edwin+, 2017)
J/MNRAS/446/3749 : SDSS nearby galaxies morphologies (Yoshino+, 2015)
J/MNRAS/410/166 : Morphological types from Galaxy Zoo 1 (Lintott+, 2011)
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID Assigned unique identifier number index
of the object (Index)
6- 24 I19 --- SDSS SDSS DR8 object id (ObjID)
26- 37 F12.8 deg RAdeg Right ascension (J2000) (ra)
39- 50 F12.8 deg DEdeg Declination (J2000) (dec)
52- 55 I4 --- run SDSS run number (run)
57- 59 I3 --- rerun SDSS rerun number (rerun)
61 I1 --- camcol SDSS Camera column (camcol)
63- 65 I3 --- field SDSS field number (field)
67- 76 F10.6 mag gMAG Rest frame absolute g magnitude (absMagG)
78- 87 F10.6 mag rMAG Rest frame absolute r magnitude (absMagR)
89- 97 F9.6 arcsec Pth50 Petrosian Radius (PetroRadr)
99-110 E12.9 --- z Spectroscopic redshift
112-120 F9.6 arcsec Rad Exponential fit scale radius (expRadr)
122-131 F10.6 deg PAfit Exponential fit position angle
(expPhir)
133-140 F8.6 --- b/a Exponential fit b/a (expABr)
142-150 F9.6 mag gcormag Simplified g magnitude corrected for
extinction (dered_g)
152-160 F9.6 mag rcormag Simplified r magnitude corrected for
extinction (dered_r)
162-169 F8.6 mag Ag Extinction in g-band (extinctiong)
171-181 F11.9 mag Ar Extinction in r-band (extinctionr)
183-192 F10.3 --- Chi2 Chi-square of GALFIT fitting (chisq)
194-198 F5.3 --- RChi2 Reduced chi-square of fitting (rchi_sq)
200-207 F8.4 pix X Position of center X axis (centerx)
209-216 F8.4 pix Y Position of center Y axis (centery)
218-224 F7.4 mag/arcsec2 SBmag Central surface brightness magnitude
(centmag)
226-232 F7.4 pix pixH Disk scale height (DSheightpix)
234-240 F7.4 pix pixR Disk scale radius (DSrad_pix)
242-249 F8.4 deg PA [] Position angle (posang) (1)
251-256 F6.4 --- DSb/a Axial ratio of disk scale height to scale
radius in edge-on fitting (axialrat)
258-264 F7.4 deg i Inclination angle (inclination)
266-276 F11.4 10+10Msun M* The extinction corrected mass (Mass)
278-289 F12.4 kpc Dist Angular diameter distance
(angulardist)
291-303 F13.4 kpc DL Luminosity distance (luminositydist)
305-311 F7.4 arcsec angH Disk scale height (dsheight)
313-319 F7.4 arcsec angR Disk scale radius (dsrad)
321-327 F7.4 kpc H Disk scale height (DSheightkpc)
329-335 F7.4 kpc R Disk scale radius (DSradkpc)
337-343 A7 --- BPX Description of BPX (BPX) (2)
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Note (1): When exponential fit b/a is less than 0.2, it is filled 90,
(Perfectly edge-on). Here a and b are semi-major and semi-minor axis
length, respectively.
Note (2): Fully described in section BP/X bulge classification, four groups of
Boxy/peanut and X-shaped description are as follows:
control = Considerated as sample without BP/X bulges, 3868 sources in
our sample
bpx- = Considerated as weak both-sided BP/X bulges sample, 1169
sources in our sample
bpx+ = Considerated as strong both-sided BP/X bulges sample,
504 sources in our sample
ones = Considerated as one-sided BP/X bulges sample, 1112
sources in our sample
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Acknowledgements:
From Atul A. Samanta, satulashutosh(at)gmail.com, IISER, Bhopal,
Ankit Kumar, UNAB, Chile
The authors gratefully acknowledge the support from Sloan Digital Sky
Survey (SDSS), Galaxy Zoo and CDS.
(End) A. Samanta [IISER], A. Kumar [UNAB], L. Trabelsi [CDS] 08-Dec-2025