Exploring the properties of low-frequency radio emission and magnetic fields in a sample of compact galaxy groups using the LOFAR Two-Metre Sky Survey (LoTSS)

TL;DR

This study uses LOFAR data to detect and analyze radio emissions and magnetic fields in compact galaxy groups, revealing widespread magnetic activity and its potential role in galaxy evolution.

Contribution

It provides the first large-scale detection of low-frequency radio emission in galaxy groups and estimates magnetic field strengths, advancing understanding of magnetic fields in these environments.

Findings

73 systems detected with radio emission

17 systems show extended radio structures

Magnetic field strengths comparable to star-forming galaxies

Abstract

We use the LOFAR Two-metre Sky Survey (LoTSS) Data Release I to identify the groups of galaxies (and individual galaxies) from the Hickson Compact Groups and Magnitude Limited Compact Groups samples that emit at the frequency of 150\,MHz, characterise their radio emission (extended or limited to the galaxies), and compare new results to earlier observations and theoretical predictions. The detection of 73 systems (and 7 more -- probably) out of 120, of which as many as 17 show the presence of extended radio structures, confirms the previous hypothesis of the common character of the magnetic field inside galaxy groups and its detectability. In order to investigate the future potential of low-frequency radio studies of galaxy groups, we also present a more detailed insight into four radio-emitting systems, for which the strength of the magnetic field inside their intergalactic medium (IGM) is calculated. The estimated values are comparable to that found inside star-forming galaxies, suggesting a dynamical and evolutionary importance of the magnetic field in galaxy groups.