* Astronomy

Title: The galaxy group NGC2563
Author: Andrea Morandi, Ming Sun, John Mulchaey, Daisuke Nagai, Massimiliano Bonamente

We present a Chandra study of the hot intragroup medium (hIGM) of the galaxy group NCG2563. The Chandra mosaic observations, with a total exposure time of ~430 ks, allow the gas density to be detected beyond R_200 and the gas temperature out to 0.75 R_200. This represents the first observational measurement of the physical properties of a poor groups beyond R_500. By capitalizing on the exquisite spatial resolution of Chandra that is capable to remove unrelated emission from point sources and substructures, we are able to radially constrain the inhomogeneities of gas ("clumpiness"), gas fraction, temperature and entropy distribution. Although there is some uncertainty in the measurements, we find evidences of gas clumping in the virialization region, with clumping factor of about 2 - 3 at R_200. The gas clumping-corrected gas fraction is significantly lower than the cosmological baryon budget. These results may indicate a larger impact of the gas inhomogeneities with respect to the prediction from hydrodynamic numerical simulations, and we discuss possible explanations for our findings.

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