J/MNRAS/521/1502 WALLABY Hydra I cl. H I galaxy morphometrics (Holwerda+, 2023)
WALLABY Pilot Survey: hydra cluster galaxies UV and H I morphometrics.
Holwerda B.W., Bigiel F., Bosma A., Courtois H.M., Deg N., Denes H.,
Elagali A., For B.-Q., Koribalski B., Leahy D.A., Lee-Waddell K.,
Lopez-Sanchez A.R., Oh S.-H., Reynolds T.N., Rhee J., Spekkens K., Wang J.,
Westmeier T., Wong O.I.
<Mon. Not. R. Astron. Soc. 521, 1502-1517 (2023)>
=2023MNRAS.521.1502H 2023MNRAS.521.1502H (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Galaxies, group ; Galaxies, nearby ;
Intergalactic medium ; Photometry, hydrogen-line ; H I data ;
Morphology ; Positional data ; Velocity dispersion ;
Galaxies, radius
Keywords: galaxies: disc - galaxies: ISM - galaxies: kinematics and dynamics -
galaxies: spiral - galaxies: statistics - galaxies: structure
Abstract:
Galaxy morphology in atomic hydrogen (H I) and in the ultraviolet (UV)
are closely linked. This has motivated their combined use to quantify
morphology over the full H I disc for both H I and UV imaging. We
apply galaxy morphometrics: concentration, asymmetry, gini, M20 and
multimode-intensity-deviation statistics to the first moment-0 maps of
the WALLABY Survey of galaxies in the hydra cluster centre. Taking
advantage of this new H I survey, we apply the same morphometrics over
the full H I extent on archival GALEX FUV and NUV data to explore how
well H I truncated, extended ultraviolet disc (XUV) and other
morphological phenomena can be captured using pipeline WALLABY data
products. Extended H I and UV discs can be identified relatively
straightforward from their respective concentration. Combined with
WALLABY H I, even the shallowest GALEX data are sufficient to identify
XUV discs. Our second goal is to isolate galaxies undergoing
ram-pressure stripping in the H I morphometric space. We employ four
different machine learning techniques, a decision tree, a k-nearest
neighbour, a support-vector machine, and a random forest. Up to 80 per
cent precision and recall are possible with the random forest giving
the most robust results.
Description:
In principle, the appearance of galaxies is a direct result of the
processes that formed and shaped them. Turning their appearance into a
qualified value, while accounting for viewing angle is a long-standing
undertaking in observational extragalactic astronomy.
While most morphology quantifications focus on the stellar component
of galaxies, a very information-rich view of gas-rich galaxies is the
21-cm line emission of neutral hydrogen (H I). In this paper, we
apply the galaxy morphometrics originally developed for stellar discs,
which were applied with some success on H I data in the past but on
often heterogeneous data. The optimal application is therefore within
a single survey although careful comparisons can successfully be made
between instrument setups of different surveys. We use the statmorph
implementation of these morphometrics. Starting with the early
Widefield ASKAP L-band Legacy All-sky Blind surveY data , we apply the
image morphometrics on H I and GALEX FUV data to explore their
utility in identifying disturbed H I discs, H I deficient or
truncated discs, and extended UV discs.
WALLABY has run its own sofia software to produce source catalogues
and source images/spectra for the team to work on. The WALLABY team
internal data release covers a subregion of the core of the hydra
cluster in a region of the cube that is relatively clean from
artefacts. WALLABY has run its own sofia software to produce source
catalogues and source images/spectra for the team to work on. The
WALLABY team internal data release covers a subregion of the core of
the hydra cluster in a region of the cube that is relatively clean
from artefacts H I detections done with sofia were linked across a
spatial and spectral radius of 2 with a minimum size requirement for a
reliable source of 8 spatial pixels and 5 spectral channels. The
resulting detections were inspected by eye to remove obvious artefacts
that were unlikely to be genuine H I sources. After manual removal
of artefacts, 272 detections remain. This data set was released
internally to the WALLABY team as hydra TR2. We use the internal
moment-0 maps the 3D mask cube, and the sofia source catalog.
As explained in section 3, We use the statmorph package to compute the
morphometrics. We utilize a Gaussian smoothing kernel with a 1 pixel
full width at half-maximum (6 arcsec) for both H I and GALEX UV
implementations of statmorph. More, we computed
Concentration-Asymmetry-Smoothness morphometrics, Gini, M20 parameters
and also multimode-intensity-deviation morphometrics to complete our
catalog presented in table.dat. The full 30 square degree
spectral-line cubes can be accessed on the CSIRO ASKAP Science Data
Archive (https://data.csiro.au/domain/casdaObservation) with the DOI:
https://doi.org/10.25919/5f7bde37c20b5 for this data set.
Objects:
----------------------------------------------------------------------------
RA (2000) DE Designation(s)
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10 36 36.00 -27 31 03.9 Hydra I Cluster = 1E 1034.3-2716
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table.dat 998 272 Astrometric informations and morphometric
parameters of our HI WALLABY galaxies
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See also:
J/MNRAS/493/5089 : HI asymmetries with LVHIS, VIVA, and HALOGAS
(Reynolds+, 2020)
J/MNRAS/489/5723 : ASKAP HI imaging of the Lyon Group of Galaxies 351
(For+, 2019)
J/MNRAS/458/963 : CANDELS galaxy structure classification (Peth+, 2016)
J/MNRAS/427/3159 : Quantified HI morphology. VI. NUV/FUV (Holwerda+, 2012)
J/MNRAS/416/2401 : HI morphology of 28 THINGS galaxies (Holwerda+, 2011)
J/MNRAS/416/2415 : Morphological parameters of WHISP galaxies (Holwerda+, 2011)
J/MNRAS/416/2437 : Quantified H I morphology of WHISP sample (Holwerda+, 2011)
J/A+A/596/A100 : Planck high-z source candidates catalog (PHZ) (Planck+,2016)
J/A+A/442/137 : HI observations of WHISP disk galaxies (Noordermeer+, 2005)
J/ApJ/915/70 : WALLABY pilot survey: HI gas in Hydra cluster (Wang+, 2021)
J/ApJ/733/74 : GALEX - SDSS properties of local galaxies (Lemonias+, 2011)
J/ApJ/731/28 : UV star-forming association in spiral galaxies
(Alberts+, 2011)
J/AJ/136/2563 : HI Nearby Galaxy Survey, THINGS (Walter+, 2008)
J/AJ/128/163 : Galaxy morphological classification (Lotz+, 2004)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
Byte-by-byte Description of file: table.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID Number in the WALLABY SoFiA catalog (id)
5- 18 A14 --- WALLABY Identification in the WALLABY SoFiA
catalog (catid)
20- 26 F7.2 pix Xpos The x-position in the mosaic data cube
(x)
28- 34 F7.2 pix Ypos The y-position in the mosaic data cube
(y)
36- 42 F7.2 pix Zpos The z-position in the mosaic data cube
(z)
44- 47 I4 pix Xmin Minimum x-pixel in the cutout (x_min)
49- 52 I4 pix Xmax Maximum x-pixel in the cutout (x_max)
54- 57 I4 pix Ymin Minimum y-pixel in the cutout (y_min)
59- 62 I4 pix Ymax Maximum y-pixel in the cutout (y_max)
64- 67 I4 pix Zmin Minimum z-pixel in the cutout (z_min)
69- 72 I4 pix Zmax Maximum z-pixel in the cutout (z_max)
74- 79 I6 --- Npix Number of pixels in the object (n_pix)
81- 89 F9.6 --- Fmin Minimum flux value (f_min)
91- 98 F8.6 --- Fmax Maximum flux value (f_max)
100-107 F8.1 --- Fsum Summed flux in the cutout (f_sum)
109-114 F6.4 --- Rel Rel value quantity always 0 (rel)
116-118 F3.1 --- FlagS SoFiA flag (flag)
120-127 F8.6 --- RMS Root-mean-square noise estimate (rms)
129-137 F9.1 --- W20 The 20% flux width (w20)
139-147 F9.1 --- W50 The 50% flux width (w50)
149-153 F5.2 arcsec MajAxis Major axis of the aperture ellipse
(ell_maj)
155-159 F5.2 arcsec MinAxis Minor axis of the aperture ellipse
(ell_min)
161-166 F6.2 deg PA [] Position angle of the aperture
ellipse (ell_pa)
168-173 F6.2 arcsec MajAxis3s Major axis of the aperture ellipse
(ell3s_maj)
175-179 F5.2 arcsec MinAxis3s Minor axis of the aperture ellipse
(ell3s_min)
181-186 F6.2 deg PA3s [] Position angle of the aperture
ellipse (ell3s_pa)
188-193 F6.2 deg PAkin Kinematic position angle (kin_pa)
195-198 F4.2 pix e_Xpos Uncertainty in the central x-position
(err_x)
200-203 F4.2 pix e_Ypos Uncertainty in the central y-position
(err_y)
205-208 F4.2 pix e_Zpos Uncertainty in the central z-position
(err_z)
210-215 F6.1 --- e_Fsum Uncertainty in the summed flux
(errfsum)
217-224 F8.4 deg RAdeg Right Ascension central position (J2000)
(ra)
226-233 F8.4 deg DEdeg Declination central position (J2000)
(dec)
235-247 F13.2 Hz Freq Frequency of the central pixel position
(freq)
249-322 A74 --- Comm Comments (comments)
324-341 F18.15 pix Xcpos Statmorph centroid central pixel
x-position (xc_centroid)
343-360 F18.15 pix Ycpos Statmorph centroid central pixel
y-position (yc_centroid)
362-381 F20.18 --- Ellc Ellipticity of the centroid
(ellipticity_centroid)
383-400 F18.16 deg Elonc Elongation of the centroid
(elongation_centroid)
402-422 F21.18 deg Orienc Orientation of the centroid
(orientation_centroid)
424-441 F18.15 pix Xasypos Central x-position for asymmetry measure
(xc_asymmetry)
443-460 F18.15 pix Yasypos Central y-position for asymmetry measure
(yc_asymmetry)
462-480 F19.17 --- Ellasy Ellipticity of the asymmetry aperture
(ellipticity_asymmetry)
482-499 F18.16 deg Elonasy Elongation of the asymmetry aperture
(elongation_asymmetry)
501-521 F21.18 deg Orienasy Orientation of the asymmetry aperture
(orientation_asymmetry)
523-541 F19.16 arcsec Rcircp Circular Petrosian radius (rpetro_circ)
543-561 F19.16 arcsec Rellp Elliptical Petrosian radius
(rpetro_ellip)
563-581 F19.16 arcsec Rcirchl Circular half-light radius (rhalf_circ)
583-601 F19.16 arcsec Rellhl Elliptical half-light radius
(rhalf_ellip)
603-621 F19.16 arcsec R20 The 20% of flux radius
(input for concentration) (r20)
623-641 F19.16 arcsec R80 The 80% of flux radius
(input for concentration) (r80)
643-661 F19.17 --- Gini Gini parameter (Gini)
663-681 F19.16 --- M20 M20 parameter (M20)
683-685 F3.1 --- FGM20 FGM20 value quantity always 0
(FG;M20)
687-689 F3.1 --- SGM20 SGM20 value quantity always 0
(SG M20)
691-709 F19.15 --- SNRpix Signal-to-noise per pixel (snperpixel)
711-728 F18.16 [-] log(R80/R20) Concentration log (r80/r20) (C)
730-748 F19.17 --- Circ Asymmetry (A)
750-769 F20.18 --- Smooth Smoothness (S)
771-791 F21.15 --- SersAmp Sersic fit amplitude (sersic_amplitude)
793-812 F20.17 arcsec SersRhl Sersic fit half-light radius
(sersic_rhalf)
814-836 F23.20 --- SersN Sersic fit index (sersic_n)
838-855 F18.15 pix SersXpos Sersic fit central x-position (sersic_xc)
857-874 F18.15 pix SersYpos Sersic fit central y-position (sersic_yc)
876-896 F21.18 --- SersEll Sersic fit ellipticity (sersic_ellip)
898-917 F20.18 deg SersPA Sersic fit on-sky angle (position angle)
(sersic_theta)
919-921 F3.1 --- Skym Mean sky value (sky_mean)
923-925 F3.1 --- Skymed Median sky value (sky_median)
927-929 F3.1 --- Skysig Standard deviation of sky pixels
(sky_sigma)
931-933 F3.1 --- SersQ Flag for the quality of Sersic fit
(flag_sersic)
935-954 F20.18 --- M Multimode (M)
956-976 F21.19 --- I Intensity (I)
978-998 F21.19 --- D Deviation (D)
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History:
From electronic version of the journal
License: CC-BY-4.0
(End) Luc Trabelsi [CDS] 28-May-2026