Co Luminosity Functions For FIR and B-Band Selected Galaxies and the First Estimate for ΩHI+H2

Dusan Keres, University of Massachusetts - Amherst
Min S. Yun, University of Massachusetts - Amherst
J. S. Young, University of Massachusetts - Amherst

This paper was harvested from ArXiv identifier is arXiv:0209413v1


We derive a non-parametric CO luminosity function using a FIR and an optical B-band selected sample of the galaxies included in the FCRAO Extragalactic CO Survey. The FIR selected sample is defined using the IRAS Bright Galaxy Surveys (BGS; IRAS 60 micron flux density ≥ 5.24 Jy). Although our CO sample is not complete, the normalization using the BGS reproduces the IRAS 60 micron luminosity function in excellent agreement with those found in the literature. Similarly, a Bband selected sample defined using the Revised Shapley-Ames (RSA) catalog is used to derive a CO luminosity function for a comparison. A Schechter function describes the both derived CO luminosity functions reasonably well. Adopting the standard CO-to-H2 conversion factor, we derive a molecular gas density of ΡH2 = (3.1 ± 1.2) × 107hM⊙ Mpc−3 for the local volume. Combining with the measurements of the local HI mass density and the helium contribution, we estimate that the total mass density of cold neutral gas in the local universe is Ωgas = (4.3±1.1)×10−4h−1, which is about 20% of the total stellar mass density Ω*