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Related Experiment Video

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Investigation of Early Plasma Evolution Induced by Ultrashort Laser Pulses

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Published on: July 2, 2012

Cosmic gamma-ray background from structure formation in the intergalactic medium

¹Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA. aloeb@cfa.harvard.edu

|May 23, 2000

Summary

This summary is machine-generated.

Cosmic structure formation generates relativistic electrons that scatter cosmic microwave background photons, explaining the diffuse gamma-ray background. This finding aligns with cosmological models and Big Bang nucleosynthesis predictions.

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Published on: January 30, 2020

Area of Science:

Cosmology
Astrophysics
High-energy astrophysics

Background:

The origin of the diffuse gamma-ray background is a major unsolved problem in cosmology.
Discrete sources like active galactic nuclei account for less than 25% of the observed gamma-ray flux.

Purpose of the Study:

To explain the origin of the diffuse gamma-ray background radiation.
To link large-scale structure formation to gamma-ray emission.

Main Methods:

Modeling shock waves in the intergalactic medium during cosmic structure formation.
Simulating the scattering of cosmic microwave background photons by relativistic electrons produced by these shocks.

Main Results:

Shock waves in the intergalactic medium generate highly relativistic electrons.
These electrons scatter cosmic microwave background photons to gamma-ray energies, producing the diffuse background.
The model's predicted flux matches observations across four orders of magnitude in photon energy.

Conclusions:

The diffuse gamma-ray background is generated locally by cosmic structure formation processes.
The model predicts the gamma-ray background is isotropic to within 5% on angular scales larger than one degree.
The agreement implies a mean cosmological baryon density consistent with Big Bang nucleosynthesis.