Upgraded GMRT observations of the Coma cluster of galaxies: The observations

TL;DR

This study uses upgraded GMRT observations at multiple frequencies to map the Coma cluster, revealing detailed radio structures and spectral properties of its sources, with implications for understanding synchrotron cooling.

Contribution

The paper presents high-resolution radio maps of the Coma cluster at two frequency bands, providing detailed morphological and spectral data for its radio sources for the first time.

Findings

Majority of sources show steep spectra consistent with synchrotron cooling

Median spectral index is -0.78, with about 59% of sources having steep spectra

Detailed images of 32 brightest sources are presented

Abstract

We have used the upgraded Giant Metrewave Radio Telescope to map the Coma cluster of galaxies at 250-500 MHz and 1050-1450 MHz bands. These 6.26 arcsec and 2.18 arcsec resolutions observations allow detailed radio structures to be determined of all detected radio sources that show both discrete pointlike and extended morphologies. We present images of a subset of 32 brightest (flux density >= 30 mJy) and dominant sources, and several sources show discrete pointlike radio morphologies. We find the steepening of the spectra consistent with synchrotron cooling in the majority of sources and the median for spectral indices is -0.78, suggesting that ~59% sources have steep spectra. The nature and the statistical properties of the radio sources in the Coma cluster will be discussed in subsequent papers.