Kinematic constraints beyond z ≃ 0 using calibrated GRB correlations

¹ Istituto Nazionale di Fisica Nucleare (INFN), Laboratori Nazionali di Frascati, 00044 Frascati, Italy
e-mail: orlando.luongo@lnf.infn.it
² Scuola di Scienze e Tecnologie, Università di Camerino, 62032 Camerino, Italy
³ NNLOT, Al-Farabi Kazakh National University, Al-Farabi av. 71, 050040 Almaty, Kazakhstan

Received: 25 April 2020
Accepted: 3 July 2020

Abstract

Context. The dynamics of the Universe are revised using high-redshift data from gamma-ray bursts to constrain cosmographic parameters by means of model-independent techniques.

Aims. Considering samples from four gamma-ray burst correlations and two hierarchies up to j₀ and s₀, respectively, we derived limits over the expansion history of the Universe. Since cosmic data span outside z ≃ 0, we investigated additional cosmographic methods such as auxiliary variables and Padé approximations

Methods. Beziér polynomials were employed to calibrate our correlations and heal the circularity problem. Several Markov chain Monte Carlo simulations were performed on the model-independently calibrated Amati, Ghirlanda, Yonetoku, and combo correlations to obtain 1 − σ and 2 − σ confidence levels and to test the standard cosmological model.

Results. Reasonable results are found up to j₀ and s₀ hierarchies, respectively, only partially alleviating the tension on local H₀ measurements as j₀ hierarchy is considered. Discussions on systematic errors have been extensively reported here.

Conclusions. Our findings show that the ΛCDM model is not fully confirmed using gamma-ray bursts. Indications against a genuine cosmological constant are summarized and commented on in detail.