Quasars: standard candles up to z=7.5 with the precision of Supernovae Ia

Understand

Currently, the $\Lambda$ Cold Dark Matter model, which relies on the existence of cold dark matter and a cosmological constant $\Lambda$, best describes the Universe.

• However, we lack information in the high-redshift ($z$) region between Type Ia Supernovae (SNe Ia) (up to $z=2.26$) and the Cosmic Microwave Background ($z=1100$), an interval crucial to test cosmological models and their possible evolution.
• We have defined a sample of 983 Quasars up to $z=7.54$ with reduced intrinsic dispersion $\delta=0.007$ which determines the matter density parameter $\Omega_M$ with the same precision of SNe Ia.
• Although previous analysis have been used Quasars as cosmological tools (e.g.