The Arecibo Legacy Fast ALFA Survey: The ALFALFA Extragalactic HI Source Catalog

TL;DR

The ALFALFA survey catalogues approximately 31,500 extragalactic HI sources, providing detailed data and spectra, and reports additional OH megamasers, offering a comprehensive resource for extragalactic radio astronomy research.

Contribution

This paper presents a large, detailed catalog of extragalactic HI sources from the ALFALFA survey, including data processing methods and spectral information, with insights into data complexities and user considerations.

Findings

Catalog of ~31,500 HI sources up to z < 0.06.

Detection of nine confirmed and ten candidate OH megamasers.

Detailed data reduction and catalog construction process.

Abstract

We present the catalog of ~31500 extragalactic HI line sources detected by the completed ALFALFA survey out to z < 0.06 including both high signal-to-noise ratio (> 6.5) detections and ones of lower quality which coincide in both position and recessional velocity with galaxies of known redshift. We review the observing technique, data reduction pipeline, and catalog construction process, focusing on details of particular relevance to understanding the catalog's compiled parameters. We further describe and make available the digital HI line spectra associated with the catalogued sources. In addition to the extragalactic HI line detections, we report nine confirmed OH megamasers and ten OH megamaser candidates at 0.16 < z < 0.22 whose OH line signals are redshifted into the ALFALFA frequency band. Because of complexities in data collection and processing associated with the use of a feed-horn array on a complex single-dish antenna in the terrestrial radio frequency interference environment, we also present a list of suggestions and caveats for consideration by users of the ALFALFA extragalactic catalog for future scientific investigations.