Аннотация
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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