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arXiv · 2112.00052

Do reverberation-measured H$\beta$ quasars provide a useful test of cosmology?

Narayan Khadka·Mary Loli Martínez-Aldama·Michal Zajaček·Bożena Czerny·Bharat Ratra
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Abstract

We use 118 H$\beta$ quasar (QSO) observations in the redshift range $0.0023 \leq z \leq 0.89$ to simultaneously constrain cosmological model parameters and QSO 2-parameter radius-luminosity ($R-L$) relation parameters in six different cosmological models. We find that the $R-L$ relation parameters for these QSOs are independent of the assumed cosmology so these QSOs seem to be standardizable through the $R-L$ relation (although there is a complication that might render this untrue). Cosmological constraints obtained using these QSOs are weak, more favor currently decelerated cosmological expansion, and typically are in $\sim 2\sigma$ tension with those obtained from a joint analysis of baryon acoustic oscillation and Hubble parameter measurements. Extending the $R-L$ relation to a 3-parameter one to try to correct for the accretion rate effect does not result in a reduction of the cosmological constraints discrepancy nor does it result in the hoped-for significant reduction of the intrinsic scatter of the $R-L$ relation.

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Narayan Khadka, Mary Loli Martínez-Aldama, Michal Zajaček, Bożena Czerny, Bharat Ratra. 2021-11-30. Do reverberation-measured H$\beta$ quasars provide a useful test of cosmology?. https://doi.org/10.1093/mnras%2Fstac914

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