Premium
The duty cycle of the radio mode feedback
Author(s) -
Bîrzan L.,
Rafferty D.A.,
Nulsen P.E.J.,
McNamara B.R.,
Röttgering H.J.A.,
Wise M.W.
Publication year - 2013
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.201211864
Subject(s) - cooling flow , duty cycle , physics , intracluster medium , astrophysics , active galactic nucleus , cluster (spacecraft) , bubble , luminosity , galaxy cluster , galaxy , observatory , flux (metallurgy) , flow (mathematics) , astronomy , power (physics) , mechanics , thermodynamics , materials science , computer science , metallurgy , programming language
The Chandra X‐ray Observatory has revealed X‐ray bubbles in the intracluster medium (ICM) of many nearby clusters, which are thought to be created by the central active galactic nucleus (AGN). However, the duty cycle of such AGN outbursts is not well understood. In order to further understand how cooling is balanced by bubble heating we studied complete samples of cooling flow clusters (from the Brightest 55 clusters of galaxies sample, B55, and the HIghest X‐ray FLUx Galaxy Cluster Sample, HIFLUGCS). We found that there is a radio luminosity cut‐off of 2.5×10 30 erg s –1 Hz –1 for the cooling flow clusters. Furthermore, we find a duty cycle for radio mode feedback, the fraction of time that a system possesses bubbles inflated by its central radio source, of ≳ 69 % for the B55 sample and ≳ 63 % for the HIFLUGCS sample. These duty cycles are lower limits since some bubbles are likely missed in existing images. We used simulations to constrain the bubble power that might be present and remain undetected in the cooling flow systems without detected bubbles. Among theses systems, almost all could have significant bubble power. Therefore, our results imply that the duty cycle of AGN outbursts with the potential to heat the gas significantly in cooling flow clusters is at least 60% and could approach 100 %. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)