J/A+A/634/A4 3 X-ray galaxy clusters radio images (Mandal+, 2020)
Revived fossil plasma sources in galaxy clusters.
Mandal S., Intema H.T., van Weeren R.J., Shimwell T.W., Botteon A.,
Brunetti G., de Gasperin F., Bruggen M., Di Gennaro G., Rottgering H.J.A.,
Hardcastle M., Tasse C.
<Astron. Astrophys. 634, A4 (2020)>
=2020A&A...634A...4M 2020A&A...634A...4M (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Radio sources ; Radio lines
Keywords: radiation mechanisms: non-thermal - X-rays: galaxies: clusters -
galaxies: clusters: individual: Abell 2593 -
galaxies: clusters: individual: Abell 2048 -
galaxies: clusters: individual: SDSS-C4-DR3-3088 -
galaxies: clusters: intracluster medium
Abstract:
It is well established that particle acceleration by shocks and
turbulence in the intra-cluster medium can produce cluster-scale
synchrotron emitting sources. However, the detailed physics of these
particle acceleration processes is still not well understood. One of
the main open questions is the role of fossil relativistic electrons
that have been deposited in the intracluster medium (ICM) by radio
galaxies. These synchrotron-emitting electrons are very difficult to
study as their radiative lifetime is only tens of Myr at gigahertz
frequencies, and they are therefore a relatively unexplored
population. Despite the typical steep radio spectrum due to
synchrotron losses, these fossil electrons are barely visible even at
radio frequencies well below the gigahertz level. However, when a
pocket of fossil radio plasma is compressed, it boosts the visibility
at sub-gigahertz frequencies, creating what are known as radio
phoenices. This compression can be the result of bulk motion and
shocks in the ICM due to merger activity. In this paper we demonstrate
the discovery potential of low-frequency radio sky surveys to find and
study revived fossil plasma sources in galaxy clusters. We used the
150MHz TIFR GMRT Sky Survey (TGSS) and the 1.4GHz NVSS sky survey to
identify candidate radio phoenices. A subset of three candidates was
studied in detail using deep multi-band radio observations (LOFAR and
GMRT), X-ray observations (Chandra or XMM-Newton), and archival optical
observations. Two of the three sources are new discoveries. Using
these observations, we identified common observational properties
(radio morphology, ultra-steep spectrum, X-ray luminosity, dynamical
state) that will enable us to identify this class of sources more
easily, and will help us to understand the physical origin of these
sources.
Description:
We observed two of our targets (Abell 2593 and SDSS-C4-DR3-3088) with
the GMRT at 325 and 610MHz (project codes 31_018 and 33_014), while
for the third target (Abell 2048) we used archival observations at the
same frequencies (project codes 15HRA01 and 16_065).
Objects:
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RA (ICRS) DE Designation(s) (z)
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23 24 13.0 +14 41 38 Abell 2593 = ACO 2593 (0.041)
09 46 45.4 +54 25 37 SDSS-C4-DR3-308 (0.046)
15 15 09.7 +04 24 37 Abell 2048 = ACO 2048 (0.097)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 131 12 List of fits images
fits/* . 12 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- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 50 A21 "datime" Obs.date Observation date
52- 58 F7.2 MHz Freq ? Observed frequency
60- 64 I5 Kibyte size Size of FITS file
66- 96 A31 --- FileName Name of FITS file, in subdirectory fits
98-131 A34 --- Title Title of the FITS file
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Acknowledgements:
Soumyajit Mandal, mandal(at)strw.leidenuniv.nl
(End) Patricia Vannier [CDS] 10-Jan-2020