Dimming of supernovae and gamma ray busts by Compton Scattering and its cosmological implications

TL;DR

This paper investigates how Compton scattering by free electrons causes dimming of supernovae and gamma-ray bursts, affecting cosmological measurements and emphasizing the need for correction in future surveys.

Contribution

It quantifies the Compton dimming effect on supernovae and gamma-ray bursts and highlights its importance for accurate cosmological parameter estimation.

Findings

Compton dimming reaches 0.004 mag at redshift 1

Dimming reaches 0.01 mag at redshift 2

Effect can bias dark energy constraints if uncorrected

Abstract

Free electrons deplete photons from type Ia supernovae through the (inverse) Compton scattering. This Compton dimming increases with redshift and reaches 0.004 mag at $z=1$ and 0.01 mag at $z=2$. Although far from sufficient to invalidate the existence of dark energy, it can bias constraint on dark energy at a level non-negligible for future supernova surveys. This effect is correctable and should be incorporated in supernova analysis. The Compton dimming has similar impact on cosmology based on gamma ray bursts as standard candles.