David Fernández Arenas, Elena Terlevich, Roberto Terlevich, Jorge Melnick, Ricardo Chávez, Fabio Bresolin, Eduardo Telles, Manolis Plionis, Spyros Basilakos
Monthly Notices of the Royal Astronomical Society, Volume 474, Issue 1, February 2018, Pages 1250–1276
Publication year: 2018

Summary 

The relationship between the integrated H β line luminosity and the velocity dispersion of the ionized gas of H II galaxies and giant H II regions represents an exciting standard candle that presently can be used up to redshifts z ∼ 4. Locally it is used to obtain precise measurements of the Hubble constant by combining the slope of the relation obtained from nearby (z ≤ 0.2) H II galaxies with the zero-point determined from giant H II regions belonging to an ‘anchor sample’ of galaxies for which accurate redshift-independent distance moduli are available. We present new data for 36 giant H II regions in 13 galaxies of the anchor sample that includes the megamaser galaxy NGC 4258. Our data are the result of the first 4 yr of observation of our primary sample of 130 giant H II regions in 73 galaxies with Cepheid determined distances. Our best estimate of the Hubble parameter is 71.0 ± 2.8(random) ± 2.1(systematic) km s− 1Mpc− 1. This result is the product of an independent approach and, although at present less precise than the latest SNIa results, it is amenable to substantial improvement.