Molecular gas in the early-type starburst galaxy NGC 3928

Abstract

Observations of 12 CO J=1→0, 2→1, 3→2 and 13 CO J=1→0 emission in the SO/a galaxy NGC 3928, which is believed to be undergoing nuclear starburst, are reported. The line ratios are consistent with optically thick 12 CO lines with molecular gas at least as warm as that in the Galactic disk. The physical conditions of the molecular gas in NGC 3928 are likely comparable to the molecular gas in the nuclear regions of spiral galaxies. The molecular gas is confined to an 11″ (0.9 kpc) disk with an average surface density of 400 M ○. /pc 2 and is clearly associated with the miniature spiral disk, which may have been captured by an otherwise gas-poor elliptical galaxy