Luminous Supermassive Black Holes in the Brightest Cluster Galaxies

2015-08-06 ISAS astro seminar

Shutaro Ueda (ISAS/JAXA)

Title: 
Abstract:
Supermassive black holes (SMBHs) in the central galaxies of clusters of galaxies (i.e.,
in the brightest cluster galaxies; BCGs) are the most massive BH in the Universe. Their
masses are estimated to be up to 1011 M. The SMBHs in nearby BCGs have a slight gas
accretion rate, which is typically less than 1 % of the Eddington limit. This indicates
that their mass growth may be performed at the early stage of evolution of their hosted
cluster. However its mechanism is still under debate. We therefore search for quasar
hosted BCGs (i.e., with high accretion rate) systematically by referring both the Planck
SZ cluster catalogue and the Swift hard X-ray catalogue. We find two sources out of 1203
clusters, which are the Phoenix cluster and H1821+643 cluster. We also investigate their
surrounding environment by using X-ray observations with Chandra and Suzaku. We find the
neutral iron K-shell line (Fe I) from both quasars and heavily absorption component from
the quasar of the Phoenix cluster. We discuss the environments of both quasars and the
origin of neutral medium surrounding quasars.