The missing cosmic baryons found?

Behar, E. and Dado, S. and Dar, A. and Laor, A. (2010) The missing cosmic baryons found? Il nuovo cimento C, 33 (5). pp. 53-60. ISSN 1826-9885

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The angular power spectrum of the cosmic microwave background radiation (CMB), the relative abundances of primordial hydrogen, deuterium and helium isotopes, and the large-scale structure of the universe all indicate that 4.5% of the current mass density of the universe consists of baryons. However, only a small fraction of these baryons can be accounted for in stars and gas inside galaxies, galaxy groups and galaxy clusters, and in spectral-line absorbing gas in the intergalactic medium (IGM). Too hot to show up in Lyman-absorption, too cool to cause detectable spectral distortions of the cosmic microwave background radiation, and too diffused to emit detectable X-rays, about 90% of the cosmic baryons remain missing in the local universe (redshift z ∼ 0). Here, we report on prevalent, isotropic, source independent, and fairly uniform soft X-ray absorption along the lines of sight to high-z gamma-ray bursts (GRBs) and quasars. It has the magnitude, redshift and energy dependence that are expected from a hot diffused IGM that contains the missing cosmological baryons and has a mean metallicity similar to that in the intracluster medium (ICM) of galaxy clusters.

Item Type: Article
Uncontrolled Keywords: Cosmology ; γ-ray sources; γ-ray bursts ; Quasars
Subjects: 500 Scienze naturali e Matematica > 530 Fisica
Depositing User: Marina Spanti
Date Deposited: 02 Apr 2020 14:40
Last Modified: 02 Apr 2020 14:40

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