The H i Content of Spirals. I. Field Galaxy H i Mass Functions and H i Mass--Optical Size Regressions

Abstract

A standard parametric maximum-likelihood technique is used to determine both the probability distribution over total HI mass M HI and the regression of this quantity on the linear optical diameter D o for eld giant spirals (Sa-Sc) from a complete HI-ux-limited data set of these objects. This sample is extracted from a subset of the optical magnitude-limited Catalog of Galaxies and Clusters of Galaxies comprised of galaxies observed in the 21 cm HI line and located in the lowest density environments of the Pisces-Perseus supercluster region bounded by 22 h R:A: 3 h , 0 Dec: 40 .Gaussian and Schechter parametrizations of the HI mass function are explored. We nd that the available data are equally well described by both models, and that the di erent morphological classes of giant spirals have HI mass functions which, in general, agree well within the errors. The largest discrepancy corresponds to the Sb-type systems which exhibit a de cit of low HI-mass objects relative to the other types.Using a straightforward generalization of the gaussian model, we have also investigated the linear dependence of M HI on D o . We con rm that the HI content of spirals is much better predicted by the size of their optical disks than by their morphological types alone. The inferred correlations imply a considerable decrease of the ratio M HI =D 2 o with increasing galaxy size for types earlier than Sc.

Hα3: an Hαimaging survey of HI selected galaxies from ALFALFA

“…Here, combining isolated LTGs from the Local Supercluster with the lowest density objects in the Coma supercluster we obtain C 1 = 7.50 and C 2 = 0.79, consistently with the Local Supercluster alone (and with the Coma1 cloud, see Boselli & Gavazzi 2009). These coefficients are consistent with those adopted by Solanes et al (1996) up to Sc galaxies, and by Toribio et al (2011) up to Scd-Sd galaxies. Figure 3 shows the relations among M HI and the diameters found adopting these coefficients.…”

“…The coefficients C 1 and C 2 were determined by Haynes & Giovanelli (1984) by studying a control sample of isolated objects, and later, on a larger sample by Solanes et al (1996). Both samples are composed almost exclusively of giant spirals however.…”

“…Given the abundant number statistics offered by SDSS, it is possible to investigate this effect as a function of galaxy inclination in the plane of the sky. For disk galaxies (Sa through Sdm) the inclination incl with respect to the line of sight was computed following Solanes et al (1996) assuming that spirals are oblate spheroids of intrinsic axial ratio q:…”

H i observations of galaxies in the southern filament of the Virgo Cluster with the Square Kilometre Array Pathfinder KAT-7 and the Westerbork Synthesis Radio Telescope

“…where the mean hybrid H I surface density is obtained from the ratio of the integrated H I flux density S H I of the galaxy in Jy km s −1 and its apparent optical diameter a in arcminutes (Solanes, Giovanelli & Haynes 1996):…”

Parkes H I observations of galaxies behind the southern Milky Way

“…A better estimate of the effect of the cluster environment on the H i content of the Norma spiral galaxies is the H i deficiency parameter (Giovanelli & Haynes 1985) which compares the H i content of a cluster galaxy with the average H i content of an isolated field spiral of the same morphological type. Solanes et al (1996) have shown that the H i content of a field spiral also depends on the diameter. However, due to the uncertainties in diameter of our highly obscured galaxies we have not included the diameter dependence in our calculations.…”