TY - JOUR
T1 - A Combined Low-Radio Frequency/X-Ray Study of Galaxy Groups. I. Giant Metrewave Radio Telescope Observations At 235 Mhz and 610 Mhz
AU - Giacintucci, S
AU - O'Sullivan, E
AU - Vrtilek, J
AU - David, LP
AU - Raychaudhury, Somak
AU - Venturi, T
AU - Athreya, RM
AU - Clarke, TE
AU - Murgia, M
AU - Mazzotta, P
AU - Gitti, M
AU - Ponman, Trevor
AU - Ishwara-Chandra, CH
AU - Jones, C
AU - Forman, WR
PY - 2011/5/1
Y1 - 2011/5/1
N2 - 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.
AB - 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.
KW - galaxies: clusters: general
KW - X-rays: galaxies: clusters
KW - galaxies: active
KW - intergalactic medium
KW - radio continuum: galaxies
U2 - 10.1088/0004-637X/732/2/95
DO - 10.1088/0004-637X/732/2/95
M3 - Article
SN - 1538-4357
VL - 732
SP - 95
JO - The Astrophysical Journal
JF - The Astrophysical Journal
IS - 2
ER -