Seeking the Missing Baryons of the Universe in the Intergalactic Medium

by Prof. Ehud Behar

at Physics Colloquium

Tue, 30 May 2023, 15:15
Ilse Katz Institute for Nanoscale Science & Technology (51), room 015


The atom (baryon) content of the universe is well known from big-bang nucleosynthesis and the cosmic microwave background. However, in the local universe only ~10% of the baryons are found in galaxies. It is natural to search for the remaining baryons in the intergalactic medium (IGM), but only ~50% are found there. According to cosmological simulations, the remaining baryons should be in a diffuse warm-hot phase of the IGM that is almost impossible to observe. X-ray absorption of γ-ray burst (GRB) afterglows is not well measured and only poorly understood, yet it may provide a unique tool to probe the diffuse IGM on cosmological distances. In particular, it features a strong dependence on redshift that optical absorbers do not. I will discuss the interpretation of GRB X-ray afterglow absorption in the context of the diffuse IGM and confront it with new cosmological simulations, suggesting we may have found the missing baryons.

Created on 27-02-2023 by Maniv, Eran (eranmaniv)
Updaded on 17-05-2023 by Maniv, Eran (eranmaniv)