Suzaku observations of the merging cluster abell 85: Temperature map and impact direction

Nobuhiro Tanaka, Akihiro Furuzawa, Shigeru J. Miyoshi, Takayuki Tamura, Tadafumi Takata

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10 Citations (Scopus)


To investigate the present situation of the merging in the southern outer region of Abell 85, we carried out long time (∼ lOOks) observations with Suzaku, and produced an X-ray hardness ratio map. We found a high hardness ratio peak on the east side of a subcluster located south of the cluster; an X-ray spectrum of the region including this peak indicates a high temperature of ∼ 8.5 keV. This hot spot has not been reported so far. We consider that this hot spot is a postshock region produced by the infall of the subcluster from the southwest. By using the Rankine- Hugoniot jump conditions for shocks, the Mach number and the infall velocity of the subcluster were obtained as 1.5 ±0.2 and 1950-280 +290km s-1, respectively, in the case of merging with the subcluster from the southwest direction. By using the difference in redshift between A 85 and the subcluster obtained from optical observations, the angle between the line of sight and the direction of the motion of the subcluster is estimated to be 75°+7°-8°,. We estimate the kinetic energy of the subcluster and the energy used for the intracluster medium (ICM) heating to be ∼ 1063 and ≲8 × l060erg, respectively. This shows that the deceleration of the subcluster by the ICM heating has been negligibly small.

Original languageEnglish
Pages (from-to)743-754
Number of pages12
JournalPublications of the Astronomical Society of Japan
Issue number3
Publication statusPublished - 2010
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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