Gamma-ray bursts as cosmological probes: LambdaCDM vs. conformal gravity

Understand

LambdaCDM, for the currently preferred cosmological density Omega_0 and cosmological constant Omega_Lambda, predicts that the Universe expansion decelerates from early times to redshift z~0.9 and accelerates at later times.

• On the contrary, the cosmological model based on conformal gravity predicts that the cosmic expansion has always been accelerating.
• To distinguish between these two very different cosmologies, we resort to gamma-ray bursts (GRBs), which have been suggested to probe the Universe expansion history at z>1, where identified type Ia supernovae (SNe) are rare.
• We use the full Bayesian approach to infer the cosmological parameters and the additional parameters required to describe the GRB data available in the literature.