J/A+A/704/A284 Multifrequency images of 3 giant radio galaxies (Wolnik+, 2025)
Multifrequency study of three giant radio galaxies with recurrent jet-formation
activity: J1021+1216, J1528+0544, and J2345-0449. I. Radio observations.
Wolnik K., Jamrozy M.
<Astron. Astrophys. 704, A284 (2025)>
=2025A&A...704A.284W 2025A&A...704A.284W (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, radio ; Interferometry ; Radio continuum
Keywords: galaxies: active - galaxies: individual: J1021+1216 -
galaxies: individual: J1528+0544 - galaxies: individual: J2345-0449 -
radio continuum: galaxies
Abstract:
The general population of radio galaxies, there exist several
classes of peculiar objects. Among them, there are giant radio
galaxies (GRGs with linear sizes greater than 0.7Mpc and
double-double radio galaxies (DDRGs) showing signs of recurrent
jet-formation activity. Observations and models developed in recent
decades suggest that recurrent activity, among other factors, may
stimulate the growth of the GRGs. However, the connection between the
two classes of objects is still poorly understood and few of the known
giant DDRGs were thoroughly studied.
Our goal is to perform a detailed study of selected giant DDRGs -
J1021+1216, J1528+0544, and J2345-0449. The collection of radio maps
along with the basic parameters of the sources, such as independent
measurements of flux density in the inner and outer lobes,
measurements of linear sizes and axial ratio of the lobes, will
facilitate further in-depth modeling of the objects performed in the
second part of our study.
In this study, we perform multifrequency radio observations of the
selected sources with Karl G. Jansky Very Large Array and the upgraded
Giant Metrewave Radio Telescope. Analysis of the radio-lobe morphology
and the structure of the spectral index maps provides preliminary
information about the sources' environment and activity.
Outer doubles with asymmetric backflows and minor misalignments were
observed in J1021+1216, J1528+0544, and J2345-0449. In J2345-0449,
there appear low surface brightness wings close to the core. In all
three sources, the shorter lobe is the brighter one, suggesting the
existence of large scale inhomogeneties in the ambient medium. A trace
of emission with low values of spectral index appears in the
J1528+0544 outer double maps, possibly marking the orientation of the
jet in the initial phase of activity. Asymmetries of the inner lobes
in J1021+1216 and J2345-0449 can be explained by relativistic
Doppler effect, while the J1528+0544 inner double structure requires a
contamination of the radio cocoon.
The shown examples of asymmetric backflows and wings in the outer
doubles of the studied sources show the existence of inhomogeneities
of the external medium around the host galaxies on the scale of the
radio-lobe size, suggesting a complex evolution of the radio cocoons.
The initial jets seem to clear the ambient medium for the subsequent
phases of activity. Spectral aging analysis and dynamical modeling,
made in the second part of this study, are necessary to confirm the
results.
Description:
The full set of radio maps, convolved to common beam sizes, used in
this study.
Objects:
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RA (2000) DE Designation(s)
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10 21 24.21 +12 17 05.4 J1021+1216 = [KJK2017] J1021+1216
15 28 04.96 +05 44 28.2 J1528+0544 = [KJK2017] J1528+0544
23 45 32.71 -04 49 25.3 J2345-0449 = [KJK2017] J2345-0449
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 104 50 List of fits images
fits/* . 50 Individual fits images
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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- 22 I3 --- Nx Number of pixels along X-axis
24- 26 I3 --- Ny Number of pixels along Y-axis
28- 37 A10 "datime" Obs.date Observation date
39- 49 E11.6 Hz Freq Observed frequency
51- 54 I4 Kibyte size Size of FITS file
56- 67 A12 --- FileName Name of FITS file, in subdirectory fits
69-104 A36 --- Title Title of the FITS file
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Acknowledgements:
Kamil Wolnik, kamil.wolnik(at)doctoral.uj.edu.pl
(End) Patricia Vannier [CDS] 23-Oct-2025