http://www.isas.jaxa.jp/topics/002198.html
2017/01/22
A very deep Chandra observation of the Perseus cluster: shocks, ripples and conduction
http://adsabs.harvard.edu/abs/2006MNRAS.366..417F
http://chandra.harvard.edu/photo/2005/perseus/
http://chandra.harvard.edu/photo/2005/perseus/
Fig.3 Colour image made from the 0.3–1.2 (red), 1.2–2 (green) and 2–7 keV (blue) bands. A 10-arcsec smoothed image has been scaled to 80 per cent of its intensity and then subtracted in order to bring out fainter features lost in the high-intensity range of raw images. The blue structure to the N of the nucleus is caused by absorption in the infalling high-velocity system, We suspect that these arc-like pressure minima are old bubbles. projected at least 60 kpc in front of the nucleus of NGC 1275 (Gillmon, The large size of these bubbles could indicate that the activity was Sanders & Fabian 2004).
2016/03/04
2015/10/23
2006/11/22
A very deep Chandra observation of the Perseus cluster: shocks, ripples and conduction
MNRAS, 2006
We present the first results from a very deep Chandra X-ray observation of the core of the Perseus cluster of galaxies. A pressure map reveals a clear thick band of high pressure around the inner radio bubbles. The gas in the band must be expanding outwards and the sharp front to it is identified as a shock front, yet we see no temperature jump across it; indeed, there is more soft emission behind the shock than in front of it. We conclude that in this inner region either thermal conduction operates efficiently or the co-existing relativistic plasma seen as the radio mini-halo is mediating the shock. If common, isothermal shocks in cluster cores mean that we cannot diagnose the expansion speed of radio bubbles from temperature measurements alone. They can at times expand more rapidly than currently assumed without producing significant regions of hot gas. Bubbles may also be significantly more energetic. The pressure ripples found in earlier images are identified as isothermal sound waves. A simple estimate based on their amplitude confirms that they can be an effective distributed heat source able to balance radiative cooling. We see multiphase gas with about 109Msolar at a temperature of about 0.5 keV. Much, but not all, of this X-ray emitting cooler gas is spatially associated with the optical filamentary nebula around the central galaxy, NGC1275. A residual cooling flow of about 50Msolaryr-1 may be taking place. A channel is found in the pressure map along the path of the bubbles, with indications found of outer bubbles. The channel connects in the south (S) with a curious cold front.
We present the first results from a very deep Chandra X-ray observation of the core of the Perseus cluster of galaxies. A pressure map reveals a clear thick band of high pressure around the inner radio bubbles. The gas in the band must be expanding outwards and the sharp front to it is identified as a shock front, yet we see no temperature jump across it; indeed, there is more soft emission behind the shock than in front of it. We conclude that in this inner region either thermal conduction operates efficiently or the co-existing relativistic plasma seen as the radio mini-halo is mediating the shock. If common, isothermal shocks in cluster cores mean that we cannot diagnose the expansion speed of radio bubbles from temperature measurements alone. They can at times expand more rapidly than currently assumed without producing significant regions of hot gas. Bubbles may also be significantly more energetic. The pressure ripples found in earlier images are identified as isothermal sound waves. A simple estimate based on their amplitude confirms that they can be an effective distributed heat source able to balance radiative cooling. We see multiphase gas with about 109Msolar at a temperature of about 0.5 keV. Much, but not all, of this X-ray emitting cooler gas is spatially associated with the optical filamentary nebula around the central galaxy, NGC1275. A residual cooling flow of about 50Msolaryr-1 may be taking place. A channel is found in the pressure map along the path of the bubbles, with indications found of outer bubbles. The channel connects in the south (S) with a curious cold front.
2000/01/01
Chandra Observation of Abell 2142: Survival of Dense Subcluster Cores in a Merger
http://adsabs.harvard.edu/abs/2000ApJ...541..542M
Markevitch et al. 2000.
The cold front cluster.
Markevitch et al. 2000.
The cold front cluster.
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