J/A+A/686/A82 Cool-core clusters at 144MHz (Biava+, 2024)
First evidence of a connection between cluster-scale diffuse radio emission
in cool-core galaxy clusters and sloshing features.
Biava N., Bonafede A., Gastaldello F., Botteon A., Brienza M.,
Shimwell T.W., Brunetti G., Bruno L., Rajpurohit K., Riseley C.J.,
van Weeren R.J., Rossetti M., Cassano R., De Gasperin F., Drabent A.,
Rottgering H.J.A., Edge A.C., Tasse C.
<Astron. Astrophys. 686, A82 (2024)>
=2024A&A...686A..82B 2024A&A...686A..82B (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Interstellar medium ; Radio sources
Keywords: acceleration of particles - radiation mechanisms: non-thermal -
radiation mechanisms: thermal -
galaxies: clusters: intracluster medium -
large-scale structure of Universe
Abstract:
Radio observations of a few cool-core galaxy clusters have revealed
the presence of diffuse emission on cluster scales, similar to what
was found in merging clusters in the form of radio halos. These
sources might suggest that a minor merger, while not sufficiently
energetic to disrupt the cool core, could still trigger particle
acceleration in the intracluster medium on scales of hundreds of
kiloparsecs. We aim to verify the occurrence of cluster-scale diffuse
radio emission in cool-core clusters and test the minor merger
scenario. With the LOw Frequency ARray (LOFAR) at 144MHz, we observed
a sample of twelve cool-core galaxy clusters presenting some level of
dynamical disturbances, according to X-ray data. We also performed a
systematic search of cold fronts in these clusters, re-analysing
archival Chandra observations. The clusters PSZ1G139.61+24, A1068 (new
detection), MS 1455.0+2232, and RX J1720.1+2638 present diffuse radio
emission on a cluster scale. This emission is characterised by a
double component: a central mini-halo confined by cold fronts and
diffuse emission on larger scales, whose radio power at 144 MHz is
comparable to that of radio halos detected in merging systems with the
same cluster mass. The cold fronts in A1068 are a new detection. We
also found a candidate plasma depletion layer in this cluster. No
sloshing features are found in the other eight clusters. Two of them
present a mini-halo, with diffuse radio emission confined to the
cluster core. We also found a new candidate mini-halo. Whereas, for
the remaining five clusters, we did not detect halo-like emission. For
clusters without cluster-scale halos, we derived upper limits to the
radio halo power. We found that cluster-scale diffuse radio emission
is not present in all cool-core clusters when observed at a low
frequency, but it is correlated to the presence of cold fronts. The
coexistence of cluster-scale diffuse radio emission and cold fronts in
cool-core clusters requires a specific configuration of the merger and
so it puts some constraints on the turbulence, which deserves to be
investigated in the future with theoretical works.
Description:
The sample consists of 12 cool-core galaxy clusters observed with
LOFAR at 144MHz. Attached are provided the high resolution images of
each cluster. We also re-analysed archival Chandra data to look for
cold fronts. The observations that we used are given in table 2.
High resolution (∼6 arcsec) LOFAR HBA images at 144MHz centred on the
cluster, flux corrected to align with the LoTSS survey.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
sources.dat 57 12 List of studied sources
list.dat 131 12 List of fits images
fits/* . 12 Individual fits images
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Byte-by-byte Description of file: sources.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Name Source name
20- 21 I2 h RAh Right ascension (J2000)
23- 24 I2 min RAm Right ascension (J2000)
26- 30 F5.2 s RAs Right ascension (J2000)
32 A1 --- DE- Declination sign (J2000)
33- 34 I2 deg DEd Declination (J2000)
36- 37 I2 arcmin DEm Declination (J2000)
39- 43 F5.2 arcsec DEs Declination (J2000)
45- 57 A13 --- FileName Name of the fits image in subdirectory fits
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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- 51 A22 "datime" Obs.date Observation date
53- 57 I5 Kibyte size Size of FITS file
59- 71 A13 --- FileName Name of FITS file, in subdirectory fits
73-131 A59 --- Title Title of the FITS file
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Acknowledgements:
Nadia Biava, nadia.biava2(at)unibo.it
(End) Patricia Vannier [CDS] 15-Mar-2024