2004/05/05 by A. Finoguenov, M. J. Henriksen, U. G. Briel +2 · 2 citations
Physics and Astronomy · #Amplitude #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Galaxy #Geology #Mach number #Mechanics #Optics #Physics #Quake (natural phenomenon) #Ridge #Surface brightness #astro-ph
paper · pdf · doi:10.1086/422246
published as Astrophys.J. 611 (2004) 811-820 · ApJ in press, 10 pages
arxiv created 2004/05/05 · openalex publication_date 2004/08/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Using a mosaic of six XMM-Newton observations, we study the hydrodynamic state of A3562, a cluster in the center of the Shapley supercluster. The X-ray image reveals a sharp surface brightness gradient within the core of A3562, a 200 kpc ridge extending to the southwest. A nearby group, SC 1329-313, imaged within this program also exhibits a tail aligned with the ridge. Study of the pressure and entropy identified the ridge with a 40% pressure enhancement. An associated Mach number of 1.15 relative to a polytropic sound speed for a 5 keV plasma requires the velocity of the group to be 1400 km s -1 , while the projected velocity difference between the cluster and the group amounts to 1200-1500 km s -1 . Apparent disruption of the group, if attributed to the ram pressure, also requires the velocity of the group in the cluster frame to amount to 1700 ± 150 km s -1 . The sharp surface brightness gradient at the center is identified with a contact discontinuity, which together with dovetails in the large-scale entropy distribution reveals a sloshing of the bright cluster galaxy in response to the passage of the SC 1329-313 group. Using the extent of the low-entropy tails in A3562, we estimate the amplitude of sloshing motion to be 200 h kpc and the oscillation frequency to be 1 Gyr.