# Signatures from a merging galaxy cluster and its AGN population: LOFAR observations of Abell 1682

## TL;DR

This study uses LOFAR radio observations to analyze the complex radio emission structures in the merging galaxy cluster Abell 1682, revealing new diffuse emissions, old radio galaxy remnants, and potential radio halo features linked to the cluster merger.

## Contribution

First detailed low-frequency LOFAR imaging of Abell 1682 revealing new diffuse structures, old radio galaxy remnants, and candidate radio halo associated with the merger.

## Key findings

- Detection of diffuse emission indicating particle acceleration from merger activity
- Identification of an old radio galaxy with steep spectrum emission
- Discovery of a new candidate radio halo and six new giant radio galaxies

## Abstract

We present LOFAR data from 110--180~MHz of the merging galaxy cluster Abell 1682, alongside archival optical, radio and X-ray data. Our 6 arc-second resolution images at low frequencies reveal new structures associated with numerous radio galaxies in the cluster. At 20 arc-second resolution we see diffuse emission throughout the cluster over hundreds of kpc, indicating particle acceleration mechanisms are in play as a result of the cluster merger event and powerful active galactic nuclei. We show that a significant part of the cluster emission is from an old radio galaxy with very steep spectrum emission (having a spectral index of $\alpha < -2.5$). Furthermore we identify a new region of diffuse steep spectrum emission ($\alpha < -1.1$) as a candidate for a radio halo which is co-spatial with the centre of the cluster merger. We suggest its origin as a population of old and mildly relativistic electrons left over from radio galaxies throughout the cluster which have been re-accelerated to higher energies by shocks and turbulence induced by the cluster merger event. We also note the discovery of six new giant radio galaxies in the vicinity of Abell 1682.