Kavli Affiliate: Jing Wang
| First 5 Authors: Wenlin Ma, Hong Guo, Haojie Xu, Michael G. Jones, Chuan-Peng Zhang
| Summary:
We present the first HI mass function (HIMF) measurement for the recent FAST
All Sky HI (FASHI) survey and the most complete measurements of HIMF in the
local universe thus far. We obtained these results by combining the HI
catalogues from HI Parkes All Sky Survey (HIPASS), Arecibo Legacy Fast ALFA
(ALFALFA) and FASHI surveys at redshift 0 < z < 0.05, covering 76% of the
entire sky. We adopted the same methods to estimate the distances, calculate
the sample completeness, and determine the HIMF for all three surveys. The
best-fit Schechter function for the total HIMF shows a low-mass slope parameter
of alpha = -1.30 and a knee mass log(Ms) = 9.86, along with a normalisation of
phi_s = 0.00658. This gives us the cosmic HI abundance: omega_HI= 0.000454. We
find that a double Schechter function with the same slope alpha better
describes our HIMF, where the two different knee masses are log(Ms1) = 9.96 and
log(Ms2) = 9.65. We verify that the measured HIMF is marginally affected by the
choice of distance estimates. The effect of cosmic variance is significantly
suppressed by combining the three surveys and this provides a unique
opportunity to obtain an unbiased estimate of the HIMF in the Local Universe.
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