A plethora of diffuse steep spectrum radio sources in Abell 2034 revealed by LOFAR

TL;DR

LOFAR observations of Abell 2034 reveal a complex array of steep spectrum radio emissions, including filaments, a giant halo, and relics, highlighting the cluster's dynamic and intricate ICM activity.

Contribution

This study provides the first detailed low-frequency radio map of Abell 2034, uncovering diverse steep spectrum emissions and emphasizing the importance of high-resolution, low-frequency observations for understanding ICM processes.

Findings

Discovery of a bright bulb of emission connected to filamentary structures

Identification of a giant radio halo with irregular morphology

Detection of up to three radio relics misaligned with X-ray emission

Abstract

With Low-Frequency Array (LOFAR) observations, we have discovered a diverse assembly of steep spectrum emission that is apparently associated with the intra cluster medium (ICM) of the merging galaxy cluster Abell 2034. Such a rich variety of complex emission associated with the ICM has been observed in few other clusters. This not only indicates that Abell 2034 is a more interesting and complex system than previously thought but it also demonstrates the importance of sensitive and high-resolution, low-frequency observations. These observations can reveal emission from relativistic particles which have been accelerated to sufficient energy to produce observable emission or have had their high energy maintained by mechanisms in the ICM. The most prominent feature in our maps is a bright bulb of emission connected to two steep spectrum filamentary structures, the longest of which extends perpendicular to the merger axis for 0.5Mpc across the south of the cluster. The origin of these objects is unclear, with no shock detected in the X-ray images and no obvious connection with cluster galaxies or AGNs. We also find that the X-ray bright region of the cluster coincides with a giant radio halo with an irregular morphology and a very steep spectrum. In addition, the cluster hosts up to three possible radio relics, which are misaligned with the cluster X-ray emission. Finally, we have identified multiple regions of emission with a very steep spectral index that seem to be associated with either tailed radio galaxies or a shock.