X-ray absorption by the intergalactic medium

Abstract

I have studied the intergalactic medium (IGM) located in galaxy clusters and groups via the so-called "X-ray Forest" the X-ray absorption lines produced by the hot IGM. I gave a semi-analytic calculation of the X-ray forest distribution based on the Press-Schechter formalism. The warm-hot intergalactic medium - the IGM between 10⁵ - 10⁷ K - was investigated via hydrodynamic simulation. I analyzed the simulated spectra which were synthesized in a way similar to simulating the Lya forest and studied column density and the Doppler b-parameter distributions of highly-ionized metals. Finally, we studied X-ray spectra of two high-redshift quasars, S5 0836+710 and PKS 2149-306, obtained with the Chandra High Energy Transmission Grating Spectrometer (HETGS). While no absorption features were detected, a method of constraining the IGM via the X-ray forest theory was proposed. I also discuss constraining the IGM via the X-ray Gunn-Peterson test.