J/AJ/170/201 NGC 5194, 4631, 5474 point sources from X-band VLA (Dage+, 2025)
Classifying compact radio emission in nearby galaxies: A 10 GHz study of active
galactic nuclei, supernovae, anomalous microwave emission, and star-forming
regions.
Dage K.C., Koch E.W., Tremou E., Oh K., Sett S., Eibensteiner C.,
Linden S.T., Mahida A.D., Murphy E.J., Ridha Aldhalemi M., Bustani Z.,
Fawaz M.I., Harff H.J., Khalyleh A., McBride T., Mason J., Preston A.,
Rinehart C., Vinson E., Panurach T., Plotkin R.M., Rivera Sandoval L.
<Astron. J., 170, 201 (2025)>
=2025AJ....170..201D 2025AJ....170..201D
ADC_Keywords: Active gal. nuclei; Binaries, X-ray; Supernova remnants;
X-ray sources; Star Forming Region; Proper motions; Radio sources;
Millimetric/submm sources; Photometry; Galaxies; Interferometry
Keywords: Active galactic nuclei ; Supernova remnants ; X-ray binary stars
Abstract:
We present 115 compact radio point sources in three galaxies,
NGC 5474, NGC 4631, and M51, taken in the most extended
(A-)configuration of the Karl G. Jansky Very Large Array at 10GHz.
Several of these compact radio point sources have diffuse counterparts
identified in previous multiband studies of resolved radio continuum
emission. We find compact counterparts to eight star forming regions,
four anomalous microwave emission candidates, and one supernova
remnant (SN 2011dh). Nine of the compact radio sources match X-ray
counterparts, the majority of which are background galaxies. These AGN
are all within the D25 (isophotal diameter) of the host galaxy and
might act as contaminants for X-ray binary population studies,
highlighting the need for high-resolution multiband imaging. This
study showcases the broad number of science cases that require
sensitive radio facilities, like the upcoming Square Kilometre Array
and the planned next generation Very Large Array.
Description:
We reduced compact (A-configuration), X-band radio from the Very Large
Array (VLA) and archival X-ray observations from Chandra of three
galaxies, NGC 4631 (7.3Mpc), NGC 5474 (6.8Mpc), and M51 (8.58Mpc). We
were able to detect 115 compact radio point sources across all three
galaxies. We crossmatched these to existing studies of resolved radio
emission from Linden+2020 (J/ApJS/248/25), as well as X-ray from
Chandra, and compared to previous radio studies in other
bands/resolution.
For our X-ray analysis, we utilized the latest calibration files from
the Chandra Calibration Database, focusing on the full 0.3-10.0keV
energy band to ensure a comprehensive analysis of the X-ray sources.
For M51, we processed the longest available observations from 2012
(PI: Kuntz): ObsIDs 13812 (2012 September 12; 160ks),
13813 (2012 September 9; 180ks), 18314 (2012 September 20; 190ks),
13815 (2012 September 23; 68ks), and 13816 (2012 September 26; 74ks).
For NGC 5474, we used ObsID 9546 (PI: Jenkins), a 30ks observation
taken on 2007 December 3. For NGC 4361, we use a 60ks observation,
ObsID 797 (PI: Wang), taken on 2000 April 16. All observations were
taken using the Advanced CCD Imaging Spectrometer S (ASIS-S).
The field of NGC 5474, and four separate fields of M51 were observed
by the VLA in the most extended A-array configuration between 2023
June and July, with X-band receivers (8-12GHz) and two independent
2048MHz wide basebands centered at 9.0 and 11.0GHz. The bandwidth was
divided into 128MHz wide spectral windows, each sampled by 64 channels.
The total time of each observing block was 2hr long with approximately
1.1hr on source. For NGC 4631, we used archival VLA data taken with
VLA A-configuration using the X-band receiver and the same instrument
setup as for the M51 and NGC 5474. three observations were taken
between 2022 May and June. NGC 4631 field was targeted for 1hr total
per observing epoch (3hr total).
Objects:
---------------------------------------------------------------------
RA (2000) DE Designation(s)
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13 29 52.69 +47 11 42.9 M51 = NGC 5194 = NAME Whirlpool Galaxy
12 42 08.00 +32 32 29.4 NGC 4631 = NAME Whale Galaxy
14 05 01.60 +53 39 43.9 NGC 5474 = LEDA 50216
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 31 3 Galaxy Properties and Derived Parameters from Z0MGS
(Leroy+2019, J/ApJS/244/24)
table5.dat 447 115 X-band radio point source catalogs of M51 (NGC 5194),
NGC 4631, and NGC 5474
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See also:
II/335 : Revised catalog of GALEX UV sources (GUVcat_AIS GR6+7) (Bianchi+ 2017)
II/363 : The band-merged unWISE Catalog (Schlafly+, 2019)
VIII/111 : VCCS Epoch 1 Bright Catalog Release (Peters+, 2021)
IX/70 : Chandra Source Catalog Release 2 (CSC 2.1) (Evans+, 2024)
J/ApJS/65/485 : 1.49GHz Atlas of Spiral Galaxies (Condon, 1987)
J/ApJ/601/735 : M51 luminous X-ray sources (Terashima+, 2004)
J/AJ/133/2559 : Compact radio sources in spiral galaxies. II. (Maddox+, 2007)
J/MNRAS/419/2095 : HMXBs in nearby galaxies (Mineo+, 2012)
J/AJ/146/86 : Cosmicflows-2 catalog (Tully+, 2013)
J/MNRAS/437/1561 : DR 21 Chandra source catalogue (Rivilla+, 2014)
J/AJ/150/81 : CHANG-ES. IV. VLA D-configuration obs. (Wiegert+, 2015)
J/ApJ/827/46 : A deep Chandra ACIS survey of M51 (Kuntz+, 2016)
J/AJ/152/50 : Cosmicflows-3 catalog (CF3) (Tully+, 2016)
J/ApJS/244/24 : A z=0 Multiwave. Galaxy Synthesis (z0MGS). I. (Leroy+, 2019)
J/A+A/625/A19 : 33 GHz continuum map of M51 (Querejeta+, 2019)
J/ApJS/248/25 : The SFRS: 3-33GHz VLA obs. of SFRs (Linden+, 2020)
J/MNRAS/520/63 : Cl* ages, masses & extinctions of 4 gal. (Whitmore+, 2023)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Galaxy Name of the galaxy
10- 13 F4.2 Mpc Dist [6.8/8.58] Distance (1)
15- 19 F5.2 [Msun] log(M*) [8.67/10.73] Log stellar mass
21- 25 F5.2 [Msun/yr] log(SFR) [-1.27/0.65] Log star forming rate (2)
27- 31 F5.2 [-] DeltaMS [-0.28/0.38] Offset from the z=0
star-forming main sequence (3)
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Note (1): Distances from Tully+2013 (J/AJ/146/86; NGC 4631),
Tikhonov+2015 (2015AstL...41..239T 2015AstL...41..239T; NGC 5474), and
McQuinn+2016 (2016ApJ...826...21M 2016ApJ...826...21M; M51).
Note (2): Measured from a combination of GALEX-FUV (II/335) and WISE4 (II/363).
Note (3): From Leroy+2019 (J/ApJS/244/24), Equation 19.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Galaxy Name of the galaxy (1)
10- 11 I2 --- Seq [0/65] Zero-based source identifier in
Galaxy (ID) (2)
13- 23 F11.7 deg RAdeg Right Ascension (J2000)
25- 33 E9.3 deg e_RAdeg 1-σ error on RAdeg
35- 44 F10.7 deg DEdeg Declination (J2000)
46- 54 E9.3 deg e_DEdeg 1-σ error on DEdeg
56- 64 E9.3 Jy S [1.1e-5/8.8e-4] Total, integrated
Stokes I flux density
66- 74 E9.3 Jy e_S [3.8e-6/4e-5] 1-σ error on S
76- 84 E9.3 Jy/beam Speak [1.5e-5/8.6e-4] Peak Stokes I flux
density per beam (PeakS)
86- 94 E9.3 Jy/beam e_Speak [2.5e-6/5.6e-6] 1-σ error on
Speak (e_PeakS)
96- 106 F11.7 deg RA-max [190.5/211.3] Right ascension of the
maximum of the source
108- 116 E9.3 deg e_RA-max [1.2e-7/1.1e-5] 1-σ error on
RA-max
118- 127 F10.7 deg DE-max [32.5/53.7] Declination of the maximum
of the source
129- 137 E9.3 deg e_DE-max [7.5e-8/1.5e-5] 1-σ error on
DE-max
139- 147 E9.3 deg a [3.2e-5/2.2e-4] FWHM of the major axis
of the source (Maj)
149- 157 E9.3 deg e_a [3.4e-7/3.8e-5] 1-σ error on a
(e_Maj)
159- 167 E9.3 deg b [2.5e-5/1.4e-4] FWHM of the minor axis
of the source (Min)
169- 177 E9.3 deg e_b [1.7e-7/1.7e-5] 1-σ error on b
(e_Min)
179- 185 F7.3 deg PA [2.9/179.2] Position angle of the major
axis of the source measured east of
north
187- 193 F7.3 deg e_PA [0.012/180] 1-σ error on PA
195- 203 E9.3 deg a-plane [3.2e-5/2.2e-4] FWHM of the major axis
of the source in the image plane
(Maj-img-plane)
205- 213 E9.3 deg e_a-plane [3.4e-7/3.8e-5] 1-σ error on
a-plane (e_Maj-img-plane)
215- 223 E9.3 deg b-plane [2.5e-5/1.4e-4] FWHM of the minor axis
of the source in the image plane
(Min-img-plane)
225- 233 E9.3 deg e_b-plane [1.7e-7/1.7e-5] 1-σ error on
b-plane (e_Min-img-plane)
235- 241 F7.3 deg PA-plane [2.9/179.2] Position angle in the image
plane of the major axis of the source
(PA-img-plane)
243- 249 F7.3 deg e_PA-plane [0.012/180] 1-σ error on PA-plane
(e_PA-img-plane)
251- 259 E9.3 deg DC-a [0/2.1e-4] FWHM of the deconvolved
major axis of the source (DC-Maj)
261- 269 E9.3 deg e_DC-a [3.4e-7/3.8e-5] 1-σ error on DC-a
(e_DC-Maj)
271- 279 E9.3 deg DC-b [0/1.2e-4] FWHM of the deconvolved
minor axis of the source (DC-Min)
281- 289 E9.3 deg e_DC-b [1.7e-7/1.7e-5] 1-σ error on DC-b
(e_DC-Min)
291- 297 F7.3 deg DC-PA [0/178.6] Position angle of the
deconvolved major axis of the source
299- 305 F7.3 deg e_DC-PA [0.012/180] 1-σ error on DC-PA
307- 315 E9.3 deg DC-a-plane [0/2.1e-4] FWHM of the deconvolved
major axis of the source in the image
plane (DC-Maj-img-plane)
317- 325 E9.3 deg e_DC-a-plane [3.4e-7/3.8e-5] 1-σ error on
DC-a-plane (e_DC-Maj-img-plane)
327- 335 E9.3 deg DC-b-plane [0/1.2e-4] FWHM of the deconvolved
minor axis of the source in the image
plane (DC-Min-img-plane)
337- 345 E9.3 deg e_DC-b-plane [1.7e-7/1.7e-5] 1-σ error on
DC-b-plane (e_DC-Min-img-plane)
347- 353 F7.3 deg DC-PA-plane [0/178.6] Position angle in the image
plane of the deconvolved major axis
(DC-PA-img-plane)
355- 361 F7.3 deg e_DC-PA-plane [0.012/180] 1-σ error on
DC-PA-plane (e_DC-PA-img-plane)
363- 371 E9.3 Jy Isl-S [6.8e-6/8.7e-4] Total, integrated
Stokes I flux density of the island
373- 381 E9.3 Jy e_Isl-S [1.7e-6/4.7e-5] 1-σ error on
Isl-S
383- 391 E9.3 Jy/beam Isl-rms [3e-6/5.2e-6] Average background rms
value of the island
393- 402 E10.3 Jy/beam Isl-mean [-4.2e-9/8.4e-9] Averge background mean
value of the island
404- 412 E9.3 Jy/beam Res-Isl-rms [0/1.6e-5] Average residual background
rms value of the island
414- 423 E10.3 Jy/beam Res-Isl-mean [-1.7e-6/2.5e-5] Averge residual
background mean value of the island
425 A1 --- SCode Code that defines the source structure
(3)
427- 431 A5 --- eDE>eRA Uncertainty in DE > Uncertainty in RA
(true/false) (DE-Err-larger)
433- 441 E9.3 deg ePos-deg [1.6e-7/1.6e-5] Radial positional error
(pos-err-deg)
443- 447 F5.3 arcsec ePos-" [0/0.06] Radial positional error
(pos-err-arcsec)
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Note (1): Galaxies as follows:
M 51 = 66 sources
NGC 4631 = 46 sources
NGC 5474 = 3 sources
Note (2): For the original labels, which are almost entirely defined by pybdsf,
see: https://pybdsf.readthedocs.io/en/latest/write_catalog.html.
Note (3): Source structure as follows:
S = a single-Gaussian source that is the only source in the island
(16 occurrences)
C = a single-Gaussian source in an island with other sources (2 occurrences)
M = a multi-Gaussian source (1 occurrence)
History:
From electronic version of the journal
License: CC-BY-4.0
(End) Prepared by [AAS], Robin Leichtnam [CDS] 10-Jul-2026