A Combined Low-Radio Frequency/X-Ray Study of Galaxy Groups. I. Giant Metrewave Radio Telescope Observations At 235 Mhz and 610 Mhz

Research output: Contribution to journalArticle


  • S Giacintucci
  • E O'Sullivan
  • J Vrtilek
  • LP David
  • T Venturi
  • RM Athreya
  • TE Clarke
  • M Murgia
  • P Mazzotta
  • M Gitti
  • CH Ishwara-Chandra
  • C Jones
  • WR Forman

Colleges, School and Institutes


We present new Giant Metrewave Radio Telescope observations at 235 MHz and 610 MHz of 18 X-ray bright galaxy groups. These observations are part of an extended project, presented here and in future papers, which combines low-frequency radio and X-ray data to investigate the interaction between central active galactic nuclei (AGNs) and the intra-group medium (IGM). The radio images show a very diverse population of group-central radio sources, varying widely in size, power, morphology, and spectral index. Comparison of the radio images with Chandra and XMM-Newton X-ray images shows that groups with significant substructure in the X-ray band and marginal radio emission at greater than or similar to 1 GHz host low-frequency radio structures that correlate with substructures in IGM. Radio-filled X-ray cavities, the most evident form of AGN/IGM interaction in our sample, are found in half of the systems and are typically associated with small, low-, or mid-power double radio sources. Two systems, NGC5044 and NGC4636, possess multiple cavities, which are isotropically distributed around the group center, possibly due to group weather. In other systems the radio/X-ray correlations are less evident. However, the AGN/IGM interaction can manifest itself through the effects of the high-pressure medium on the morphology, spectral properties, and evolution of the radio-emitting plasma. In particular, the IGM can confine fading radio lobes in old/dying radio galaxies and prevent them from dissipating quickly. Evidence for radio emission produced by former outbursts that co-exist with current activity is found in six groups of the sample.


Original languageEnglish
Pages (from-to)95
Number of pages1
JournalThe Astrophysical Journal
Issue number2
Publication statusPublished - 1 May 2011


  • galaxies: clusters: general, X-rays: galaxies: clusters, galaxies: active, intergalactic medium, radio continuum: galaxies