X-ray Measurement of Dark Matter Temperature in Abell 1795Report as inadecuate



 X-ray Measurement of Dark Matter Temperature in Abell 1795


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We present a method from an X-ray observation of a galaxy cluster to measure the radial profile of the dark matter velocity dispersion, sigma DM, and to compare the dark matter ``temperature defined as mu m p sigma DM**2 - k B with the gas temperature. The method is applied to the XMM-Newton observation of Abell 1795. The ratio between the specific energy of the dark matter and that of the intracluster medium ICM, which can be defined as beta DM in analogy with beta spec, is found to be less than unity everywhere ranging \~0.3-0.8. In other words, the ICM temperature is higher than the dark matter ``temperature, even in the central region where the radiative cooling time is short. A beta DM value smaller than unity can most naturally be explained by heating of the ICM. The excess energy of ICM is estimated to be ~1-3 keV per particle.



Author: Yasushi Ikebe; Hans Boehringer; Tetsu Kitayama

Source: https://archive.org/







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