CO luminosity–FWHM correlation of low- and high-redshift galaxies and its possible cosmological utilization. Issue 4 (10th January 2019) - Wu, Yi-Han
ABSTRACT: A linear correlation has been proposed between the CO luminosity (${L}^{\prime }_{\rm {CO}}$ ) and the full width at half-maximum (FWHM) for high-redshift ($z$ > 1) submillimetre galaxies. However, the controversy concerning the${L}^{\prime }_{\rm {CO}}$ –FWHM correlation seems to have been caused by the use of heterogeneous samples (e.g. different transition lines) and/or data with large measurement uncertainties. In order to avoid the uncertainty caused by using different rotational transitions, in this work we make an extensive effort to select only CO( J = 1−0) data from the literature. We separate these wide-ranging redshift data into two samples: the low-redshift ($z$ < 1) and high-redshift ($z$ > 1) samples. The samples are corrected for lensing magnification factors if gravitational-lensing effects appeared in the observations. The correlation analysis shows that there exists significant${L}^{\prime }_{\rm {CO}}$ –FWHM correlations for both low-redshift and high-redshift samples. A comparison of the low- and high-redshift${L}^{\prime }_{\rm {CO}}$ –FWHM correlations does not show strong evolution with redshift. Assuming that there is no evolution, we can use this relation to determine the model-independent distances of high-redshift galaxies. We then constrain cosmological models with the calibrated high-redshift CO data and the sample of Type Ia supernovae in the Union 2.1 compilation. In the constraint for$w$ CDM with our samples, the derived values are$w$ 0 = −1.02 ± 0.17, Ωm0 = 0.30 ± 0.02 and${H}_{0}=70.00\pm {0.60}\, \, \rm {km\, s^{-1}\, Mpc^{-1}}$ .