• Siddharth Malu

Articles written in Journal of Astrophysics and Astronomy

• Discovery of a Giant Radio Halo in a Massive Merging Cluster at 𝑧 = 0.443

We have discovered a giant radio halo in the massive merging cluster MACSJ0417.5-1154. This cluster, at a redshift of 0.443, is one of the most X-ray luminous galaxy cluster in the MAssive Cluster Survey (MACS) with an X-ray luminosity in the 0.1–2.4 keV band of 2.9 × 1045 erg s-1. Recent observations from GMRT at 230 and 610 MHz have revealed a radio halo of ∼ 1.2 × 0.3 Mpc2 in extent. This halo is elongated along the North-West, similar to the morphology of the X-ray emission from Chandra. The 1400 MHz radio luminosity (𝐿r) of the halo is ∼ 2 × 1025 W Hz-1, in good agreement with the value expected from the 𝐿x - 𝐿r correlation for cluster halos.

• Clusters of Galaxies and the Cosmic Web with Square Kilometre Array

• Study of diffuse emission in cluster MACSJ0417.5-1154 from 76 MHz to 18 GHz

We present new radio observations of the massive and X-ray luminous galaxy cluster MACS J0417.5–1154, at 1.387 GHz and 18 GHz, from the Giant Metrewave Radio Telescope (GMRT) and the Australia Telescope Compact Array (ATCA) respectively.We estimate diffuse emission in the central region ofthe cluster at 1.387 GHz and 18 GHz. We combine these data with previously published results and present the spectrum of diffuse emission from 76 MHz to 18 GHz. This is possibly a unique study of the radio halo emission in galaxy cluster over this wide range of frequencies. Such studies lay the prospects of future studies with radio telescopes with wide-range of frequencies like the Square Kilometre Array (SKA). Our 1.387 GHz data, with 2$^{\prime\prime}$ angular resolution, provides a better estimate of point source emission than previous L-band observations, which is crucial, given the claim of sharp steepening of the radio halo spectrum at 0.61 GHz reported earlier. We find that the spectrum of the radio halo has a spectral index fit up to 18 GHz, and yields a spectral indexbetween 76 MHz and 18 GHz that fits the available data better than earlier L-band observations. We discuss possible reasons for the peculiar spectral characteristics of the diffuse emission.

• # Journal of Astrophysics and Astronomy

Volume 43, 2022
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• # Continuous Article Publication

Posted on January 27, 2016

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• # Editorial Note on Continuous Article Publication

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