The Subaru Seminar is
usually held in Room 104 of the Hilo Base Facility, adjacent
to the main lobby. Everyone is welcome to attend. If you are
interested in giving a seminar, please contact Subaru seminar organizers
(Tadayuki Kodama, Naoyuki Tamura, Tomonori Usuda)
by email : sseminar_at_subaru.naoj.org (please change"_at_" to @).
May 7, Monday, at 11:15 am
" The interplay between the brightest cluster galaxy and the intra-cluster medium via AGN feedback "
(Univ. of Durham, UK)
Using a sample of 123 X-ray clusters and groups drawn from the XMM-Cluster
Survey first data release, we investigate the interplay between the brightest
cluster galaxy (BCG), its black hole, and the intra-cluster/group medium (ICM).
It appears that for groups and clusters with a BCG likely to host significant
AGN feedback, gas cooling dominates in those with TX > 2 keV while AGN
feedback dominates below. This can be understood through the subunity
exponent found in the scaling relation we derive between the BCG mass
and cluster mass over the halo mass range 1013 < M500 < 1015Msol, such that
BCG AGN in groups can have relatively more energetic influence on the ICM.
The LX - TX relation for systems with the most massive BCGs, or those with
BCGs co-located with the peak of the ICM emission, is steeper than that for
those with the least massive and most offset, which instead follows
self-similarity. This is evidence that a combination of central gas cooling
and powerful, well fuelled AGN causes the departure of the ICM from pure
gravitational heating, with the steepened relation crossing self-similarity
at TX = 2 keV. Importantly, regardless of their black hole mass, BCGs are
more likely to host radio-loud AGN if they are in a massive cluster
(TX & 2 keV) and again co-located with an effective fuel supply of dense,
cooling gas. This demonstrates that the most massive black holes appear to
know more about their host cluster than they do about their host galaxy.
The results lead us to propose a physically motivated, empirical
definition of 'cluster' and 'group', delineated at 2 keV.
Seminars are also held at JAC,