Cosmic Flows : Green Bank and Parkes HI observations

TL;DR

This paper presents a comprehensive study of neutral hydrogen properties in 1,822 galaxies using Green Bank and Parkes telescopes, aiming to improve cosmic flow measurements and galaxy distance estimates.

Contribution

It provides a large, uniform dataset of HI line widths for nearly 14,000 galaxies, enhancing previous inventories and supporting various cosmological calibrations.

Findings

HI line width data for 13,941 galaxies compiled and re-measured.

The dataset supports multiple galaxy samples for distance and flow studies.

Data is publicly available through the Extragalactic Distance Database.

Abstract

The neutral hydrogen properties of 1,822 galaxies are being studied with the Green Bank 100m and the Parkes 64m telescopes as part of the 'Cosmic Flows' program. Observed parameters include systemic velocities, profile line widths, and fluxes. The line width information can be combined with optical and infrared photometry to obtain distances. The 1,822 HI observations complement an inventory of archives. All told, HI line width information is available for almost all of five samples: (i) luminosity-line width correlation calibrators, (ii) zero-point calibrators for the supernova Ia scale, (iii) a dense local sample of spiral galaxies with M_{Ks} < -21 within 3,000 km/s, (iv) a sparser sample of 60 $\mu$m selected galaxies within 6,000 km/s that provides all-sky coverage of our extended supercluster complex, and (v) an even sparser sample of flat galaxies, extreme edge-on spirals, extending in a volume out to 12,000 km/s. The HI information for 13,941 galaxies, whether from the archives or acquired as part of the Cosmic Flows observational program, is uniformly re-measured and made available through the Extragalactic Distance Database web site.