Spitzer observations of Abell 1763 - II: Constraining the nature of activity in the cluster-feeding filament with VLA and XMM-Newton data

TL;DR

This study uses VLA and XMM-Newton data to analyze galaxy activity in the Abell 1763 filament, revealing predominantly starburst activity with few AGN, and provides evidence of streaming motions feeding the cluster.

Contribution

First direct mid-infrared detection of a galaxy filament and analysis of galaxy activity using multi-wavelength data to understand cluster feeding mechanisms.

Findings

Most filament galaxies are starbursts, not AGN.

Radio and X-ray data show streaming motions along the filament.

Evidence of ram pressure stripping in the brightest cluster galaxy.

Abstract

The Abell 1763 superstructure at z=0.23 contains the first galaxy filament to be directly detected using mid-infrared observations. Our previous work has shown that the frequency of starbursting galaxies, as characterized by 24{\mu}m emission is much higher within the filament than at either the center of the rich galaxy cluster, or the field surrounding the system. New VLA and XMM-Newton data are presented here. We use the radio and X-ray data to examine the fraction and location of active galaxies, both active galactic nuclei (AGN) and starbursts. The radio far-infrared correlation, X-ray point source location, IRAC colors, and quasar positions are all used to gain an understanding of the presence of dominant AGN. We find very few MIPS-selected galaxies that are clearly dominated by AGN activity. Most radio selected members within the filament are starbursts. Within the supercluster, 3 of 8 spectroscopic members detected both in the radio and in the mid-infrared are radio-bright AGN. They are found at or near the core of Abell 1763. The five starbursts are located further along the filament. We calculate the physical properties of the known wide angle tail (WAT) source which is the brightest cluster galaxy (BCG) of Abell 1763. A second double lobe source is found along the filament well outside of the virial radius of either cluster. The velocity offset of the WAT from the X-ray centroid, and the bend of the WAT in the intracluster medium (ICM) are both consistent with ram pressure stripping, indicative of streaming motions along the direction of the filament. We consider this as further evidence of the cluster-feeding nature of the galaxy filament.