Analysis of z ≤ 0.7 Chandra Cool Target (CCT) Quasars to Calibrate the Hubble Diagram

Due to their high luminosity and abundance out to high redshifts, quasars readily present themselves as ideal candidates for cosmological probes. Despite numerous attempts to quantify a relationship intrinsic to quasars to build the Hubble Diagram, previous studies have suffered from a high dispersion when probing the cosmological parameters. Risaliti & Lusso 2015 proposed a new method of using the quasars non-linear relation between UV and X-ray luminosities to independently build a Hubble diagram up to z~6, thus testing cosmological models and constraining the cosmological parameters. In this presentation, I will introduce our most recent efforts, as part of Chandra Cool Target (CCT) projects to further decrease the dispersion in the quasar X-ray and UV luminosity relation, which covers a detailed analysis of ~30 quasars, with the results providing further insight into how we can better tailor our source selection process to minimise dispersion in addition to teaching us more about the physics of quasars.