2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/12417The transmission grating spectrometers on AXAF have sufficient sensitivity and energy resolution to detect resonance X-ray absorption lines in the spectra of distant quasars. Such lines would be produced in an ionized, and somewhat chemically enriched component of the inter-galactic medium. The bulk of the baryonic content of the universe at redshifts <=2-3 could be in this form and would thus be revealed by AXAF.3 pages, to appear in "Fundamental Parameters in Cosmology" XXXIII Rencontres de MoriondAstrophysicstext