An X-ray and Radio Study of the Hubble Frontier Field Cluster Abell S1063

TL;DR

This study combines X-ray and radio observations to analyze the complex structure, temperature, and radio halo properties of the galaxy cluster Abell S1063, revealing evidence of merging activity and insights into the halo's origin.

Contribution

It provides the first observational confirmation of the merging axis in Abell S1063 and characterizes its under-luminous radio halo with detailed X-ray and radio data.

Findings

Detection of large-scale excess brightness in X-ray residuals

Confirmation of the merging axis through residual flux mapping

Identification of an under-luminous radio halo with a steep spectrum

Abstract

We present results from \textit{Chandra} X-ray observations and 325 MHz Giant Metrewave Radio Telescope (GMRT) observations of the massive and X-ray luminous cluster of galaxies Abell S1063. We report the detection of large-scale \lq\lq excess brightness\rq\rq\ in the residual \textit{Chandra} X-ray surface brightness map, which extends at least 2.7 Mpc towards the north-east from the center of the cluster. We also present a high fidelity X-ray flux and temperature map using \textit{Chandra} archival data of 122 ksec, which shows the disturbed morphology in the cluster. The residual flux map shows the first observational confirmation of the merging axis proposed by earlier simulation by \citet{Gomez2012AJ....144...79G}. The average temperature within $R_{500}$ is $11.7 \pm 0.56$ keV, which makes AS1063 one of the hottest clusters in the nearby Universe. The integrated radio flux density at 325 MHz is found to be $62.0\pm6.3$ mJy. The integrated spectrum of the radio halo follows a power-law with a spectral index $\alpha=-1.43\pm 0.13$. The radio halo is found to be significantly under-luminous, which favored for both the hadronic as well as the turbulent re-acceleration mechanism for its origin.