Standardizing reverberationmeasured Mg II timelag quasars, by using the radiusluminosity relation, and constraining cosmological model parameters
Abstract
We use 78 reverberationmeasured Mg II timelag quasars (QSOs) in the redshift range 0.0033 ≤ z ≤ 1.89 to constrain cosmological parameters in six different cosmological models. The basis of our method is the use of the radiusluminosity or RL relation to standardize these 78 Mg II QSOs. In each cosmological model, we simultaneously determine RL relation and cosmological model parameters, thus avoiding the circularity problem. We find that the RL relation parameter values are independent of the cosmological model used in the analysis, thus, establishing that current Mg II QSOs are standardizable candles. Cosmological constraints obtained using these QSOs are significantly weaker than, but consistent with, those obtained from a joint analysis of baryon acoustic oscillation (BAO) observations and Hubble parameter [H(z)] measurements. So, we also analyse these QSOs in conjunction with the BAO + H(z) data and find cosmological constraints consistent with the standard spatially flat ΛCDM model as well as with mild dark energy dynamics and a little spatial curvature. A larger sample of higher quality reverberationmeasured QSOs should have a smaller intrinsic dispersion and so should provide tighter constraints on cosmological parameters.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 December 2021
 DOI:
 10.1093/mnras/stab2807
 arXiv:
 arXiv:2106.11136
 Bibcode:
 2021MNRAS.508.4722K
 Keywords:

 cosmological parameters;
 cosmology: observations;
 dark energy;
 quasars: emission lines;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 General Relativity and Quantum Cosmology;
 High Energy Physics  Phenomenology;
 High Energy Physics  Theory
 EPrint:
 16 pages, 11 figure, Mg II QSO data are given, MNRAS accepted version. arXiv admin note: text overlap with arXiv:2105.12692