Redshift evolution of the Amati relation: calibrated results from the Hubble diagram of quasars at high redshifts

Understand

Gamma-ray bursts (GRBs) have long been proposed as a complementary probe to type Ia supernovae (SNe Ia) and cosmic microwave background to explore the expansion history of the high-redshift universe, mainly because they are bright enough to be detected at greater distances.

• Although they lack definite physical explanations, many empirical correlations between GRB isotropic energy/luminosity and some directly detectable spectral/temporal properties have been proposed to make GRBs standard candles.
• Since the observed GRB rate falls off rapidly at low redshifts, thus preventing a cosmology independent calibration of these correlations.
• In order to avoid the circularity problem, SN Ia data are usually used to calibrate the luminosity relations of GRBs in the low redshift region (limited by the redshift range for SN Ia sample), and then extrapolate it to the high redshift region.