2009/12/31 by Myriam Gitti, Ewan O'Sullivan, Ewan O’Sullivan +5 · 3 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Brightness temperature #Galaxies: Formation, Evolution, Phenomena #Galaxy #Giant Metrewave Radio Telescope #Luminosity #Radio galaxy #Radio telescope #Ram pressure #Shock (circulatory) #Surface brightness #astro-ph.CO
paper · pdf · doi:10.1088/0004-637x/714/1/758
published as Astrophys.J.714:758-771,2010 · 14 pages, 8 figures, accepted for publication in ApJ. Revised version including minor comments and expanded discussion (version with full resolution figures available at http://hea-www.harvard.edu/~mgitti/hcg62-gitti.pdf)
arxiv created 2010/03/16 · openalex publication_date 2010/04/14 · arxiv updated 2014/11/20 · openalex created_date 2019/06/27 · openalex updated_date 2026/08/05
We report on the results of an analysis of Chandra , XMM-Newton , and new Giant Metrewave Radio Telescope (GMRT) data of the X-ray bright compact group of galaxies HCG 62, which is one of the few groups known to possess clear, small X-ray cavities in the inner regions. This is part of an ongoing X-ray/low-frequency radio study of 18 groups, initially chosen for the availability of good-quality X-ray data and evidence for active galactic nucleus/hot gas interaction. At higher frequency (1.4 GHz), the HCG 62 cavity system shows minimal if any radio emission, but the new GMRT observations at 235 MHz and 610 MHz clearly detect extended low-frequency emission from radio lobes corresponding to the cavities. By means of the synergy of X-ray and low-frequency radio observations, we compare and discuss the morphology, luminosity, and pressure of the gas and of the radio source. We find that the radio source is radiatively inefficient, with a ratio of radio luminosity to mechanical cavity power of ∼10 −4 , and that the radio pressure of the lobes is about 1 order of magnitude lower than the X-ray pressure of the surrounding thermal gas. Thanks to the high spatial resolution of the Chandra surface brightness and temperature profiles, we also identify a shock front located at 36 kpc to the southwest of the group center, close to the southern radio lobe, with a Mach number ∼1.5 and a total power which is about 1 order of magnitude higher than the cavity power. Such a shock may have heated the gas in the southern region, as indicated by the temperature map. The shock may also explain the arc-like region of enriched gas seen in the iron abundance map, as this may be produced by a non-Maxwellian electron distribution near its front.