We use six different cosmological models to study the recently released compilation of X-ray and UV flux measurements of 2038 quasars (QSOs) which span the redshift range 0.009 ≤ z ≤ 7.5413. We find, for the full QSO data set, that the parameters of the X-ray and UV luminosities LX−LUV relation used to standardize these QSOs depend on the cosmological model used to determine these parameters, i.e. it appears that the full QSO data set includes QSOs that are not standardized and so cannot be used for the purpose of constraining cosmological parameters. Subsets of the QSO data, restricted to redshifts z ≲ 1.5–1.7 obey the LX−LUV relation in a cosmological-model-independent manner, and so can be used to constrain cosmological parameters. The cosmological constraints from these lower z, smaller QSO data subsets are mostly consistent with, but significantly weaker than, those that follow from baryon acoustic oscillation and Hubble parameter measurements.
Khadka, Narayan and Ratra, Bharat. "Determining the range of validity of quasar X-ray and UV flux measurements for constraining cosmological model parameters." Monthly Notices of the Royal Astronomical Society, vol. 502, no. 4, Feb. 2021. https://doi.org/10.1093/mnras/stab486
Khadka, Narayan, & Ratra, Bharat (2021). Determining the range of validity of quasar X-ray and UV flux measurements for constraining cosmological model parameters. Monthly Notices of the Royal Astronomical Society, 502(4). https://doi.org/10.1093/mnras/stab486
Khadka, Narayan, and Ratra, Bharat, "Determining the range of validity of quasar X-ray and UV flux measurements for constraining cosmological model parameters," Monthly Notices of the Royal Astronomical Society 502, no. 4 (2021), https://doi.org/10.1093/mnras/stab486
@article{osti_1770466,
author = {Khadka, Narayan and Ratra, Bharat},
title = {Determining the range of validity of quasar X-ray and UV flux measurements for constraining cosmological model parameters},
annote = {ABSTRACT We use six different cosmological models to study the recently released compilation of X-ray and UV flux measurements of 2038 quasars (QSOs) which span the redshift range 0.009 ≤ z ≤ 7.5413. We find, for the full QSO data set, that the parameters of the X-ray and UV luminosities LX−LUV relation used to standardize these QSOs depend on the cosmological model used to determine these parameters, i.e. it appears that the full QSO data set includes QSOs that are not standardized and so cannot be used for the purpose of constraining cosmological parameters. Subsets of the QSO data, restricted to redshifts z ≲ 1.5–1.7 obey the LX−LUV relation in a cosmological-model-independent manner, and so can be used to constrain cosmological parameters. The cosmological constraints from these lower z, smaller QSO data subsets are mostly consistent with, but significantly weaker than, those that follow from baryon acoustic oscillation and Hubble parameter measurements.},
doi = {10.1093/mnras/stab486},
url = {https://www.osti.gov/biblio/1770466},
journal = {Monthly Notices of the Royal Astronomical Society},
issn = {ISSN 0035-8711},
number = {4},
volume = {502},
place = {United Kingdom},
publisher = {Oxford University Press},
year = {2021},
month = {02}}
Monthly Notices of the Royal Astronomical Society, Journal Name: Monthly Notices of the Royal Astronomical Society Journal Issue: 4 Vol. 502; ISSN 0035-8711