Probing cosmic opacity at high redshifts with gamma-ray bursts

Abstract

Probing the evolution of the universe at high redshifts with standard candles is a powerful way to discriminate dark energy models, where an open question nowadays is whether this component is constant or evolves with time. One possible source of ambiguity in this kind of analysis comes from cosmic opacity, which can mimic a dark energy behavior. However, most tests of cosmic opacity have been restricted to the redshift range $z<2$. In this work, by using luminosity distances of gamma-ray bursts, given the validity of the Amati relation, and the latest $H(z)$ data we determine constraints on the cosmic opacity at high redshifts ($z>2$) for a flat $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ model. A possible degeneracy of the results with the adopted cosmological model is also investigated by considering a flat XCDM model. The limits on cosmic opacity in the redshift range $0<z<2$ are updated with type Ia supernovae (SNe Ia) from the Union2.1 sample, where we added the most distant ($z=1.713$) spectroscopically confirmed SNe Ia. From the analyses performed, we find that both SNe Ia and gamma ray bursts samples are compatible with a transparent universe at $1\ensuremath{\sigma}$ level and the results are independent of the dark energy equation of state parameter $w$.