ABSTRACT We present results from a deep (174 ks) Chandra observation of the FR-II radio galaxy 3C 220.1, the central brightest cluster galaxy (BCG) of a kT ∼ 4 keV cluster at z = 0.61. The temperature of the hot cluster medium drops from ∼5.9 to ∼3.9 keV at ∼35 kpc radius, while the temperature at smaller radii may be substantially lower. The central active galactic nucleus (AGN) outshines the whole cluster in X-rays, with a bolometric luminosity of 2.0 × 1046 erg s−1 (∼10 per cent of the Eddington rate). The system shows a pair of potential X-ray cavities ∼35 kpc east and west of the nucleus. The cavity power is estimated within the range of 1.0 × 1044 and 1.7 × 1045 erg s−1, from different methods. The X-ray enhancements in the radio lobes could be due to inverse Compton emission, with a total 2–10 keV luminosity of ∼8.0 × 1042 erg s−1. We compare 3C 220.1 with other cluster BCGs, including Cygnus A, as there are few BCGs in rich clusters hosting an FR-II galaxy. We also summarize the jet power of FR-II galaxies from different methods. The comparison suggests that the cavity power of FR-II galaxies likely underestimates the jet power. The properties of 3C 220.1 suggest that it is at the transition stage from quasar-mode feedback to radio-mode feedback.
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Chandra view of Abell 407: the central compact group of galaxies and the interaction between the radio AGN and the ICM
Abell 407 (A407) is a unique galaxy cluster hosting a central compact group of nine galaxies (named as ‘Zwicky’s Nonet’; G1–G9 in this work) within a 30 kpc radius region. The cluster core also hosts a luminous radio active galactic nucleus (AGN), 4C 35.06 with helically twisted jets extending over 200 kpc. With a 44 ks Chandra observation of A407, we characterize the X-ray properties of its intracluster medium and central galaxies. The mean X-ray temperature of A407 is 2.7 keV and the M200 is $1.9 \times 10^{14}\, {\mathrm{M}_{\odot }}$. We suggest that A407 has a weak cool core at r < 60 kpc scales and at its very centre, <1–2 kpc radius, a small galaxy corona associated with the strong radio AGN. We also conclude that the AGN 4C 35.06 host galaxy is most likely G3. We suggest that the central group of galaxies is undergoing a ‘slow merge’ procedure. The range of the merging time-scale is 0.3 ∼ 2.3 Gyr and the stellar mass of the future brightest cluster galaxy (BCG) will be $7.4\times 10^{11} \, \mathrm{M}_{\odot }$. We find that the regions that overlap with the radio jets have higher temperature and metallicity. This is consistent with AGN feedback activity. The central entropy is higher than that for other clusters, which may be due to the AGN feedback and/or merging activity. With all these facts, we suggest that A407 is a unique and rare system in the local universe that could help us to understand the formation of a massive BCG.
more » « less- Award ID(s):
- 1714764
- NSF-PAR ID:
- 10363264
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Monthly Notices of the Royal Astronomical Society
- Volume:
- 511
- Issue:
- 3
- ISSN:
- 0035-8711
- Page Range / eLocation ID:
- p. 3994-4004
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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