J/A+A/704/A137 4C32.25, 4C61.23, MRC2011-298 uGMRT obs (Retana-Montenegro, 2025)
Wide-Field uGMRT band-3 imaging of the fields around X-shaped radio galaxies.
Spectral properties of 4C32.25 and 4C61.23.
Retana-Montenegro E.
<Astron. Astrophys. 704, A137 (2025)>
=2025A&A...704A.137R 2025A&A...704A.137R (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Galaxies, radio ; Radio continuum
Keywords: galaxies: active - galaxies: evolution - galaxies: formation -
galaxies: jets - galaxies: nuclei
Abstract:
We present wide-field upgraded Giant Metrewave Radio Telescope (uGMRT)
images of the fields around the X-shaped radio galaxies (XRGs)
4C32.25, 4C61.23, and MRC 2011-298 obtained at 400MHz. The
observations are calibrated using the extreme peeling method to
account for direction-dependent effects across the field of view, as
was previously applied to Low-Frequency ARray (LOFAR) data. Our 400
MHz images capture in fine detail the radio morphology of the XRGs, as
well as other serendipitous radio sources located in these fields. We
use these images along with archival low-frequency and high-frequency
radio data to investigate the spectral properties of the XRGs 4C32.25
and 4C61.23. Under the assumption of conditions corresponding to the
maximum radio source age, we estimate the spectral ages of both the
primary lobes and the wings. These ages indicate that the wings are
the oldest component of the XRGs and are a product of past radio
activity. Moreover, we have used the radio images available to derive
high-resolution spectral index maps for these two XRGs. We find that
the spectral index steepens from the primary lobes toward the wings,
consistent with our spectral age estimates. These results suggest that
precessional and backflow models explain the X-shaped radio morphology
of 4C32.25 and 4C61.23, respectively. Finally, taking advantage of our
wide-area images, we identify several serendipitous diffuse radio
sources located in our XRG fields and cross-reference them with
previous surveys.
Description:
The uGMRT band-3 mosaic images of the fields around the X-shaped radio
galaxies 4C32.25, 4C61.23, and MRC 2011-298. The corresponding source
catalogs are also presented here.
Objects:
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RA (2000) DE Designation(s)
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08 31 27.48 +32 19 26.8 4C32.25 = LEDA 23915
11 37 21.36 +61 20 01.1 4C61.23 = LEDA 2616039
20 14 18.69 -29 42 36.4 MRC 2011-298 = LEDA 726073
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
cat_4c32.dat 118 505 4C32.25 source catalog
cat_4c61.dat 118 799 4C61.23 source catalog
cat_mrc.dat 118 449 MRC2011-298 source catalog
list.dat 83 3 List of fits images
fits/* . 3 Individual fits images
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Byte-by-byte Description of file: cat_4c32.dat cat_4c61.dat cat_mrc.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- Source Source name (JHHMMSS.ss+DDMMSS.s)
(Source_ID)
22- 29 F8.4 deg RAdeg Right ascension (J2000) (RA)
31- 38 F8.4 deg e_RAdeg rms uncertainty on RAdeg (E_RA)
40- 47 F8.4 deg DEdeg Declination (J2000) (DEC)
49- 57 F9.4 deg e_DEdeg rms uncertainty on DEdeg (E_DEC)
59- 67 F9.4 mJy Ftotal Integrated source flux density at 400MHz
(Ftotal)
69- 76 F8.4 mJy e_Ftotal rms uncertainty on Ftotal (e_Ftotal)
78- 86 F9.4 mJy/beam Fpeak Peak flux density at 400Hz
88- 95 F8.4 mJy/beam e_Fpeak rms uncertainty on Fpeak (e_Fpeak)
97-103 F7.4 --- Fsmear Approximate correction factor to the peak
flux density to account for bandwidth-
and time-smearing (Fsmear)
105-112 F8.4 mJy/beam rms Local rms noise used for the source
detection (rms)
114 A1 --- PyBDSFCode [S/M] flag indicating the source structure
code by PyBDSF (PyBDSF_code) (1)
116 I1 --- FlagEdge [0/1] an object that is located close to
or in a facet edge, which could result in
some flux loss (Flag_edge)
118 I1 --- FlagMerged [1/2] a large diffuse source whose
separate components are merged into a
single one according to a visual
inspection (Flag_merged)
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Note (1): Flag indicating the source structure code by PyBDSF as follows:
S = a source with a single component
M = a source with multiple components
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 34 I5 Kibyte size Size of FITS file
36- 64 A29 --- FileName Name of FITS file, in subdirectory fits
66- 83 A18 --- Title Title of the FITS file
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Acknowledgements:
Edwin Retana, edwinretana(at)gmail.com
(End) Patricia Vannier [CDS] 29-Oct-2025