Galaxy formation with local photoionization feedback – II. Effect of X-ray emission from binaries and hot gas

We study how X-rays from stellar binary systems and the hot intracluster medium (ICM) aect the radiative cooling rates of gas in galaxies. Our study uses a novel implementation of gas cooling in the moving-mesh hydrodynamics code arepo. Xrays from stellar binaries do not aect cooling at all as their emission spectrum is too hard to eectively couple with galactic gas. In contrast, X-rays from the ICM couple well with gas in the temperature range 10 4 10 6 K. Idealised simulations show that the hot halo radiation eld has minimal impact on the dynamics of cooling ows in clusters