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C.M. Springob (Cornell U.)
We present a digital compilation of 21 cm line spectral profiles of over 9000 optically selected galaxies in the local universe. Redshifts and HI line fluxes and widths have been extracted from these spectra in a homogeneous fashion. We have also obtained upper limits on the fluxes of an additional ~500 galaxies. These data are being used in a variety of ongoing studies, including new estimates of the HI mass and width functions and a new sample of Tully-Fisher distances for ~5000 galaxies. We present the results for an HI mass function derived from an optical diameter and HI flux limited subset of these data for masses log(MHI/M\odot) > 7.4 which takes into account the effects of local large scale structure. The global HIMF derived for this sample is well fit by a Schechter function with \alpha = -1.24, log(M*/M\odot)=9.99, \phi*=3.2 \times 10-3 Mpc-3. These values match those derived from blind HI surveys to within the estimated uncertainties, yet our estimated HIMF is clearly lower than most other estimates at the lowest masses. We also explore the possible environmental dependence on the HIMF by computing it separately in regimes of differing cosmic density. The low mass end of the HIMF is found to be suppressed in higher density regions relative to lower density regions, although the statistical significance of the difference is low. Finally, we present results for the velocity width function derived from these data. Whereas most previous investigations of the velocity width function involved deriving a luminosity function and inferring the velocity width function from the Tully-Fisher relation, we derive the width function from the distribution of widths itself. This work has been partially supported by NSF grants AST-0307396, AST-0307661, the NRAO/GBT 03B-007 Graduate Student Support Grant, and the NASA/NY Space Grant.
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.