A new binning method to choose a standard set of Quasars

Abstract

Although the Lambda Cold Dark Matter model is the most accredited cosmological model, information at intermediate redshifts (z) between type Ia Supernovae (z = 2.26) and the Cosmic Microwave Background (z = 1100) is crucial to validate this model further. Here, we present a detailed and reliable methodology for binning the quasars (QSO) data that allows the identification of a golden sample of QSOs to be used as standard candles. This procedure has the advantage of being very general. Thus, it can be applied to any astrophysical sources at cosmological distances. This methodology allows us to avoid the circularity problem since it involves a flux–flux relation and includes the analysis of removing selection biases and the redshift evolution. With this method, we have discovered a sample of 1253 quasars up to z = 7.54 with reduced intrinsic dispersion of the relation between Ultraviolet and X-ray fluxes, with δint=0.096±0.003 (56% less than the original sample where δint=0.22). Once the luminosities are corrected for selection biases and redshift evolution, this ‘gold’ sample allows us to determine the matter density parameter to be ΩM=0.240±0.064. This value is aligned with the results of the ΛCDM model obtained with SNe Ia.