Galaxies 09: Assembly, Gas Content and Star Formation History of Galaxies

Martha Haynes
Cornell University

The HI Census from the ALFALFA Survey

The Arecibo Legacy Fast ALFA (ALFALFA) survey is an on-going blind HI survey designed to obtain a census of HI-bearing objects over a cosmologically significant volume of the local universe. To date, about 72\% of the ALFALFA observations have been completed, and the current working catalog contains some 10500 high quality detections extracted from about 1700 square degrees of sky. ALFALFA is specifically designed to detect gas rich low mass halos nearby and to probe the HI mass functions in different environments, including voids, nearby groups such as Leo, and the Virgo cluster. ALFALFA provides measures of the HI gas mass and disk rotational velocity for thousands of objects in common with SDSS, 2MASS, GALEX etc, permitting a global view of gas content and its relationship to structural properties, stellar and dynamical mass estimators, star formation and AGN indicators, and to their dependence on local environment. Here I will present an overview of recent ALFALFA results.

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