Chandra X-Ray Observations of Abell 119: Cold Fronts And A Shock In An Evolved Off-Axis Merger

TL;DR

This paper reports Chandra X-ray observations of galaxy cluster Abell 119, revealing complex structures, cold fronts, and a shock indicative of a recent or ongoing off-axis merger along the NE-SW axis.

Contribution

The study provides detailed X-ray analysis of Abell 119, identifying cold fronts and a shock, and links multi-wavelength evidence to characterize its merger dynamics.

Findings

Detection of cold fronts indicating gas sloshing.

Identification of a shock front with Mach number 1.21.

Evidence of recent or ongoing off-axis merger activity.

Abstract

We present Chandra X-ray observations of the dynamically complex galaxy cluster Abell 119 ($z = 0.044$). A119 is host to two NAT radio sources (0053-015 & 0053-016) whose tails are oriented parallel to each other despite orthogonally oriented jet axes. Imaging and spectral analysis reveal X-ray emission elongated along the NE-SW axis along with the presence of complex structures, including surface brightness discontinuities, which suggest possible merger activity along this axis. From radial profiles of the X-ray surface brightness, temperature, pressure, and density, we identify two surface brightness edges which are found to be cold fronts, possibly associated with large-scale sloshing of ICM gas. We also identify a brightness edge to the south which is found to be a shock front with Mach number $M = 1.21 \pm 0.11$, consistent with a merger shock. In addition, previous optical studies show alignment of optical substructures along the north-south direction. The elongated X-ray emission, orientations of the NAT tails, and alignment of optical substructure all suggest recent or on-going merger activity in the NE-SW direction.