# The galaxy group NGC2563

## TL;DR

This study uses deep Chandra X-ray observations to measure the properties of the hot gas in the galaxy group NGC2563 beyond the typical virial radius, revealing gas clumping and its impact on baryon content.

## Contribution

First observational measurement of hot gas properties beyond R500 in a poor galaxy group, highlighting gas clumping and deviations from simulations.

## Key findings

- Evidence of gas clumping with a factor of 2-3 at R200.
- Gas fraction is lower than the cosmological baryon budget.
- Gas inhomogeneities may be more significant than predicted by simulations.

## Abstract

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.