Mock X-Ray Observations of Hot Gas with L-Galaxies Semi-analytic Models of Galaxy Formation

We create mock X-ray observations of hot gas in galaxy clusters with a new extension of the L-Galaxies semianalyticmodel of galaxy formation, which includes the radial distribution of hot gas in each halo. Based on themodel outputs, we first build some mock light cones, then generate mock spectra with the SOXS package andderive the mock images in the light cones. Using the mock data, we simulate mock X-ray spectra for the ROSATall-sky survey, and compare the mock spectra with the observational results. Then, we consider the designparameters of the HUBS mission and simulate the observation of the halo hot gas for HUBS as an importantapplication of our mock work. We find: (1) our mock data match the observations by current X-ray telescopes. (2)The survey of hot baryons in resolved clusters by HUBS is effective below redshift 0.5, and the observations of theemission lines in point-like sources at z > 0.5 by HUBS help us understand the hot baryons in the early universe.(3) By taking advantage of the large simulation box and flexibility in semi-analytic models, our mock X-rayobservations provide the opportunity to select targets and observation strategies for forthcoming X-ray facilities.