Exploring the "L-σ" Relation of H II Galaxies and Giant Extragalactic H II Regions Acting as Standard Candles
Abstract
Cosmological applications of H II galaxies and giant extragalactic H II regions (GEHRs) to construct the Hubble diagram at high redshifts require knowledge of the "L-σ" relation of the standard candles used. In this paper, we study the properties of a large sample of 156 sources (25 high-z H II galaxies, 107 local H II galaxies, and 24 GEHRs) compiled by Terlevich et al. Using the cosmological distances reconstructed through two new cosmology-independent methods, we investigate the correlation between the Hβ emission-line luminosity L and the ionized gas velocity dispersion σ. The method is based on non-parametric reconstruction using the measurements of Hubble parameters from cosmic clocks, as well as the simulated data of gravitational waves from the third-generation gravitational wave detector (the Einstein Telescope, ET), which can be considered as standard sirens. Assuming the relation between emission-line luminosity and ionized gas velocity dispersion, $\mathrm{log}L({\rm{H}}\beta )=\alpha \mathrm{log}\sigma ({\rm{H}}\beta )+\kappa $ , we find that the full sample provides a tight constraint on the correlation parameters. However, similar analysis done on three different subsamples seems to support the scheme of treating H II galaxies and GEHRs with distinct strategies. Using the corrected "L-σ" relation for the H II observational sample beyond the current reach of Type Ia supernovae, we obtain values of the matter density parameter, Ωm = 0.314 ± 0.054 (calibrated with standard clocks) and Ωm = 0.311 ± 0.049 (calibrated with standard sirens), in the spatially flat ΛCDM cosmology.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 2020
- DOI:
- 10.3847/1538-4357/ab5b94
- arXiv:
- arXiv:1911.10959
- Bibcode:
- 2020ApJ...888..113W
- Keywords:
-
- Cosmological parameters;
- H II regions;
- Standard candles;
- 339;
- 694;
- 1563;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 9 pages, 5 figures, 1 table, accepted for publication in ApJ