Looking for the Signals of the Missing Baryons in the Extragalactic Background Light

Abstract

The missing baryons in the universe are assumed to be hidden in the whole space as a warm-hot intergalactic medium (WHIM). Finding them is one of the important subjects in modern cosmology. In this paper, we point out that the very high energy electron/positron rays may light up the WHIM due to the anomalous bremsstrahlung according to an improved Bethe-Heitler formula. The resulting excess of the extragalactic background light (EBL) can be observed by the direct measurement method. A possible explanation on the difference between the direct and indirect measurements of EBL is also proposed. Thus, we find a new window to probe the WHIM properties via the EBL.