J/A+A/698/L17 ACT-CL J0329.2-2330 MeerKAT images (Sikhosana+, 2025)
The MeerKAT massive distant clusters survey:
A radio halo in a massive galaxy cluster at z = 1.23.
Sikhosana S.P., Hilton M., Bernardi G., Kesebonye K., Klutse D.Y.,
Knowles K., Moodley K., Mroczkowski T., Oozeer N., Partridge B.,
Phuravhathu D., Sifon C., Vargas C., Wollack E.
<Astron. Astrophys. 698, L17 (2025)>
=2025A&A...698L..17S 2025A&A...698L..17S (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Radio sources
Keywords: galaxies: clusters: intracluster medium - radio continuum: galaxies -
X-rays: galaxies: clusters
Abstract:
In the current theoretical paradigm, high redshift radio halos are
expected to be scarce due to inverse Compton energy losses and
redshift dimming, which cause them to be intrinsically faint. This low
occurrence fraction is predicted by cosmic ray electron turbulent
re-acceleration models. To date, only a handful of radio halos have
been detected at redshift z>0.8. We report the MeerKAT detection of a
radio halo hosted by a galaxy cluster ACT-CL J0329.2-2330 at z=1.23,
making it the highest redshift halo detected thus far. Using L-band
and UHF-band observations, we derive a radio halo spectral index of
α1.3GHz0.8GHz=1.3±0.4 and a radio power of
P1.4GHz=(4.4±1.5(x1024W/Hz/ This result further confirms that
there is rapid magnetic field amplification in galaxy clusters at high
redshift.
Description:
MeerKAT is a 64-antenna array operated by the South African
Radio Astronomy Observatory (SARAO). MeerKAT's longest baseline is
8km, resulting in 6" resolution at L-band (900-1670MHz). Approximately
three-quarters of the antennas are located within a 1km radius, with
a minimum baseline of 29m resulting in a UHF-band maximum scale of 52',
making MeerKAT an ideal instrument for observing faint extended
emission.
The MeerKAT observations were carried out at L-band with a total
on-target time of 3.5 hours, using a dump rate of 8 seconds and 4096
channels.
Objects:
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RA (2000) DE Designation(s)
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03 29 17.71 -23 30 09.7 ACT-CL J0329.2-2330 = ACT-CL J0329.2-2330
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 145 4 List of fits images
fits/* . 4 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- 24 I5 --- Nx Number of pixels along X-axis
26- 30 I5 --- Ny Number of pixels along Y-axis
32- 52 A21 "datime" Obs.date Observation date
54- 64 E11.6 Hz Freq observed frequency
66- 71 I6 Kibyte size Size of FITS file
73-103 A31 --- FileName Name of FITS file, in subdirectory fits
105-145 A41 --- Title Title of the FITS file
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Acknowledgements:
Sinenhlanhla Sikhosana, sneprec(at)gmail.com
(End) Patricia Vannier [CDS] 02-Jun-2025