Astronomers detect radio halo in a massive galaxy cluster

A global crew of astronomers has carried out radio observations of an enormous galaxy cluster often called ACT-CL J0329.2-2330, which resulted within the detection of a brand new radio halo on this cluster. The finding was reported in a analysis paper revealed April 5 on the pre-print server arXiv.

Radio halos are monumental areas of diffuse radio emission, normally discovered on the facilities of large galaxy clusters, showcasing an everyday morphology, which tends to hint the X-ray emitting intracluster medium (ICM). Nevertheless, diffuse emissions typically have very low floor brightness, notably at GHz frequencies, which makes them onerous to detect. Their brightness will increase at lower frequencies, unveiling the presence of those areas.

Now, a bunch of astronomers led by Sinenhlanhla Treasured Sikhosana of the College of KwaZulu-Natal in Durban, South Africa, has discovered a brand new radio halo in ACT-CL J0329.2-2330 (or ACT-CL J0329 for brief)—a galaxy cluster with a mass of about 970 trillion solar lots, at a redshift of 1.23. The invention is a results of L-band and UHF-band observations of this cluster with the MeerKAT radio telescope as a part of the MeerKAT Large Distant Cluster Survey (MMDCS).

“On this letter, now we have offered MeerKAT L and UHF-band observations of ACT-CL J0329.2-2330, a galaxy cluster at z=1.23. The low-resolution images reveal a radio halo within the cluster. (…) The MeerKAT observations had been carried out at L-band with a total on-target time of three.5 hours, utilizing a dump fee of 8 seconds and 4,096 channels,” the researchers wrote.

By analyzing MeerKAT pictures, Sikhosana’s crew recognized prolonged emission on the middle of ACT-CL J0329, with a largest linear dimension of three.59 million gentle years at 1.28 GHz. MeerKAT pictures additionally present that the radio halo in ACT-CL J0329 has a easy, common morphology that traces the thermal bremsstrahlung emission of the intracluster medium (ICM).

Primarily based on these outcomes, the astronomers categorised this emission as a radio halo, which suggests that it’s the highest redshift halo to this point detected.

The examine discovered that the newly found radio halo has a flux density of three.44 and 6.11 mJy at L and UHF-band, respectively. The built-in spectral index of the halo was calculated to be 1.3, whereas its radio energy was estimated to be of 4.4 YW/Hz.

These outcomes recommend that the halo in ACT-CL J0329 is as luminous because the halos present in close by large galaxy clusters, which appears to substantiate that there’s fast magnetic area amplification in galaxy clusters at excessive redshifts.

In concluding remarks, the authors of the paper underlined that the spectral index map of ACT-CL J0329 showcases distinguishable fluctuations as steeper spectral index values are concentrated within the jap area. This may increasingly point out that the turbulent power just isn’t homogeneously dissipated within the halo quantity.

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