J/A+A/686/A44 MeerKAT L-band image of Abell 2142 (Riseley+, 2024)
A 'MeerKAT-meets-LOFAR' study of the complex multi-component (mini-)halo in the
extreme sloshing cluster Abell 2142.
Riseley C.J., Bonafede A., Bruno L., Botteon A., Rossetti M., Biava N.,
Bonnassieux E., Loi F., Vernstrom T., Balboni M.
<Astron. Astrophys. 686, A44 (2024)>
=2024A&A...686A..44R 2024A&A...686A..44R (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Photometry, infrared
Keywords: galaxies: clusters: general -
galaxies: clusters: intracluster medium -
galaxies: clusters: individual: Abell 2142 - radio continuum: general
Abstract:
Clusters of galaxies are known to be turbulent environments, whether
they are merging systems where turbulence is injected
via the conversion of gravitational potential energy into the
intracluster medium (ICM), or whether they are relaxed systems in
which small-scale core sloshing is occurring within the potential
well. In many such systems, diffuse radio sources associated with the
ICM are found: radio haloes and mini-haloes.
Abell 2142 is a rich cluster undergoing an extreme episode of core
sloshing, which has given rise to four cold fronts and a complex
multi-component radio halo. Recent work revealed that there are three
primary components to the halo that spans a distance of up to around
2.4 Mpc. The underlying physics of particle acceleration on these
scales is poorly explored, and requires high-quality multi-frequency
data with which to perform precision spectral investigation. We aim to
perform such an investigation.
We used new deep MeerKAT L-band (1283MHz) observations in conjunction
with LOFAR HBA (143MHz) data as well as X-ray data from XMM-Newton
and Chandra to study the spectrum of the halo and the connection
between the thermal and nonthermal components of the ICM.
We confirm the presence of the third halo component, detecting it for
the first time at 1283MHz and confirming its ultrasteep spectrum
nature, as we recovered an integrated spectrum of
αH3,total=11.68±0.10. All halo components follow power-law
spectra with increasingly steep spectra moving towards the cluster
outskirts. We profiled the halo in three directions, finding evidence
of asymmetry and spectral steepening along an axis perpendicular to
the main axis of the cluster. Our investigation of the thermal
non-thermal connection shows sub-linear correlations that are steeper
at 1283MHz than 143MHz, and we find evidence of different connections
in different components of the halo. In particular, we find both a
moderate anti-correlation (H1, the core) and positive correlation
(H2, the ridge) between the radio spectral index and X-ray
temperature.
Our results are broadly consistent with an interpretation of turbulent
(re-)acceleration following an historic minor cluster merger scenario
in which we must invoke some inhomogeneities. However, the
anti-correlation between the radio spectral index and X-ray
temperature in the cluster core is more challenging to explain; the
presence of three cold fronts and a generally lower temperature may
provide the foundations of an explanation, but detailed modelling is
required to study this further.
Description:
MeerKAT L-band image of the Abell 2142 field at 10 arcsecond
resolution, corrected for primary beam attenuation and truncated at a
radius of 1 degree from the phase centre. Image has been converted to
the Scaife & Heald (2012MNRAS.423L..30S 2012MNRAS.423L..30S) flux density scale.
Objects:
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RA (2000) DE Designation(s)
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15 58 14.38 +27 12 57.8 Abell 2142 = ACO 2142
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 134 1 Informations on fits image
fits/* . 1 fits image
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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- 58 I6 Kibyte size Size of FITS file
60- 99 A40 --- FileName Name of FITS file, in subdirectory fits
101-134 A34 --- Title Title of the FITS file
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Acknowledgements:
Chris Riseley, chris.riseley.astro(at)gmail.com
(End) Patricia Vannier [CDS] 15-Mar-2024