Extended Molecular Gas in the Nearby Starburst Galaxy Maffei 2

We present a 9'x9' fully-sampled map of the CO J=1-0 emission in the nearbystarburst galaxy Maffei 2 obtained at the Five College Radio AstronomyObservatory. The map reveals previously known strong CO emission in the centralstarburst region as well as an extended asymmetric distribution with bright COlines at the ends of the bar and in a feature at the north-east edge of themolecular disk. This northern feature, proposed previously to be an interactingcompanion galaxy, could be a dwarf irregular galaxy, although the CO data arealso consistent with the feature being simply an extension of one of the spiralarms. We estimate the total molecular gas mass of Maffei 2 to be (1.4-1.7)x10^9Mo or ~3-4% of its dynamical mass. Adopting the recently determined lower valuefor the CO-to-H2 conversion factor in the central region, our data lead to thesurprising result that the largest concentrations of molecular gas in Maffei 2lie at the bar ends and in the putative dwarf companion rather than in thecentral starburst. A gravitational stability analysis reveals that the extendeddisk of Maffei 2 lies above the critical density for star formation; however,whether the central region is also gravitationally unstable depends both on thedetails of the rotation curve and the precise value of the CO-to-H2 conversionfactor in this region.Comment: accepted to ApJ (Sept 10 2004 issue