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Title: On the merging cluster Abell 578 and its central radio galaxy 4C+67.13

Here we analyze radio, optical, and X-ray data for the peculiar cluster Abell 578. This cluster is not fully relaxed and consists of two merging sub-systems. The brightest cluster galaxy (BCG), CGPG 0719.8+6704, is a pair of interacting ellipticals with projected separation ~10 kpc, the brighter of which hosts the radio source 4C+67.13. The Fanaroff–Riley type-II radio morphology of 4C+67.13 is unusual for central radio galaxies in local Abell clusters. Our new optical spectroscopy revealed that both nuclei of the CGPG 0719.8+6704 pair are active, albeit at low accretion rates corresponding to the Eddington ratio $$\sim {{10}^{-4}}$$ (for the estimated black hole masses of $$\sim 3\times {{10}^{8}}\;{{M}_{\odot }}$$ and $$\sim {{10}^{9}}\;{{M}_{\odot }}$$). The gathered X-ray (Chandra) data allowed us to confirm and to quantify robustly the previously noted elongation of the gaseous atmosphere in the dominant sub-cluster, as well as a large spatial offset (~60 kpc projected) between the position of the BCG and the cluster center inferred from the modeling of the X-ray surface brightness distribution. Detailed analysis of the brightness profiles and temperature revealed also that the cluster gas in the vicinity of 4C+67.13 is compressed (by a factor of about ~1.4) and heated (from $$\simeq 2.0$$ keV up to 2.7 keV), consistent with the presence of a weak shock (Mach number ~1.3) driven by the expanding jet cocoon. As a result, this would then require the jet kinetic power of the order of $$\sim {{10}^{45}}$$ erg s–1, implying either a very high efficiency of the jet production for the current accretion rate, or a highly modulated jet/accretion activity in the system.
Authors:
ORCiD logo [1] ; ORCiD logo [2] ;  [3] ;  [4] ;  [5] ;  [5] ;  [6] ;  [3] ;  [7] ;  [1]
  1. Institute of Space and Astronomical Science JAXA, Kanagawa (Japan); Univ. of Tokyo, Tokyo (Japan)
  2. Institute of Space and Astronomical Science JAXA, Kanagawa (Japan); Jagiellonian Univ., Krakow (Poland)
  3. Harvard Smithsonian Center for Astrophysics, Cambridge, MA (United States)
  4. Naval Research Lab., Washington, D.C. (United States)
  5. Jagiellonian Univ., Krakow (Poland)
  6. SLAC National Accelerator Lab., Stanford Univ., Stanford, CA (United States)
  7. Institute of Space and Astronomical Science JAXA, Kanagawa (Japan)
Publication Date:
OSTI Identifier:
1313949
Report Number(s):
SLAC-PUB-16793
Journal ID: ISSN 1538-4357; arXiv:1503.07244
Grant/Contract Number:
AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 805; Journal Issue: 2; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC); National Aeronautics and Space Administration (NASA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; astrophysics; ASTRO; GRQC; galaxies: active; galaxies: clusters: individual (Abell 578); galaxies: individual (4C+67.13); galaxies: jets; intergalactic medium; X-rays: galaxies: clusters