Prog. Theor. Phys. Supplement No.169 (2007) pp. 25-28
Absence of Bulk Motions of the Intracluster Medium in the Centaurus Cluster
1Cosmic Radiation Laboratory, RIKEN, Wako 351-0198, Japan
2Department of Physical Science, Hiroshima University,
3Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK
4Department of Physics, Tokyo University of Science, Tokyo
5Department of Physics, The University of Tokyo, Tokyo
6NASA/Goddard Space Flight Center, Code 662, Greenbelt, MD 20771, USA
7Department of Physics, Saitama University, Saitama
8ISAS/JAXA, Sagamihara 229-8510, Japan
9Department of Physics, Tokyo Metropolitan University, Hachioji
We present results from the Suzaku observations of a nearby
cluster, the Centaurus cluster (z = 0.0104). Three pointing observations of
the cluster were carried out with the Suzaku XIS in December 2005,
and the Doppler shift of the iron K lines was investigated in detail
to constrain the bulk velocity of the intracluster medium (ICM) in
its core region. From the spectral analysis, no significant
velocity difference was detected within calibration uncertainty of
±700 km s-1 over a spatial scale of 50 kpc in the
central 240 kpc region. The 90% upper limit on the line-of-sight
velocity is < 1400 km s-1, giving a tighter constraint
than the previous measurements. The significant velocity gradients
inferred from the previous Chandra observations were not detected in
two pairs of regions near the cluster core. These results suggest
that the bulk velocity does not largely exceed the thermal velocity
of the gas in the central region of the Centaurus
cluster. Implications of the present results for the estimation of
the cluster mass are discussed.
DOI : 10.1143/PTPS.169.25
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Citing Article(s) :
Progress of Theoretical Physics Supplement No.169 (2007) pp. 65-70
Summary of the Conference Papers on Clusters of Galaxies
Takaya Ohashi and J. Patrick Henry