Double relics in Abell 2345 and Abell 1240: spectral index and polarization analysis

TL;DR

This study uses VLA radio observations to analyze the spectral index and polarization of double relics in galaxy clusters Abell 1240 and Abell 2345, testing formation models and revealing diverse relic properties.

Contribution

It provides new detailed radio observations and analysis of double relics, comparing results with theoretical models to understand their formation mechanisms.

Findings

Double relics in Abell 1240 match outgoing merger shock models.

One relic in Abell 2345 has unusual morphology and spectral profile.

Results support different formation scenarios for the relics.

Abstract

The aim of the present work is to study the radio properties of double relics in Abell 1240 and Abell 2345 in the framework of double relic formation models. We present new Very Large Array observations at 20 and 90 cm for these two clusters. We performed spectral index and polarization analysis and compared our results with expectations from theoretical models. The presence of double relics in these two cluster is confirmed by these new observations. Double relics in Abell 1240 show radio morphology, spectral index and polarization values in agreement with "outgoing merger shocks" models. One of the relics of Abell 2345 shows a peculiar morphology and spectral index profile, that are difficult to reconcile with present scenarios. We suggest a possible origin for this peculiar relic.