1994PASP..106..549H

This dissertation is an investigation of the basic morphology and dynamics of the galaxy Maffei 2, undertaken at a variety of wavelengths ranging from the near infrared (1.3 micron) to the radio (21 cm). Although it is relatively nearby (∼5 Mpc) and large in extent (∼10'), Maffei 2 was only discovered and identified about 20 years ago because of visual extinction from intervening dust in the Galactic plane. Observations at longer wavelengths have shown it to exhibit the characteristics of a starburst galaxy. Strong emission in the far infrared and radio continuum together with large quantities of molecular gas all point to vigorous massive star formation in its nucleus.

We have observed Maffei 2 at a number of key wavelengths in an attempt to build up a consistent model for the dynamical processes driving the starburst. High resolution ^13CO (1-0) observations from Owens Valley Millimeter Interferometer allow us to trace the density distribution of molecular gas in the nuclear starburst region with high fidelity. Single dish ^12CO(3-2) observations of the nucleus made with the Caltech Submillimeter Observatory probe the physical conditions in the warmer molecular regions in the starburst. Near infrared observations obtained with NOAO's SQIID allow us to penetrate the obscuring dust in the plane of the Milky Way to see the overall morphology of the galaxy. HI mapping of the galaxy with the NRAO VLA reveals the kinematics of the extended disk, allowing us to see the mechanisms of large-scale gas flow.

Our studies have led to the conclusion that Maffei 2 is a strongly barred galaxy with nuclear star formation most likely triggered by a recent interaction. From near infrared images we make the first determination of this obscured galaxy's Hubble type: SBb(s) pec. The stellar bar and spiral arms, which can be traced at several wavelengths, display striking asymmetries reminiscent of tidally interacting galaxies. The large-scale velocity field has a strong non-circular component that is typical of barred galaxies. The nuclear gas lies along a narrow ridge that is generally aligned with the bar and is apparently the product of a density wave extending to within tens of parsecs of the dynamical center. Nuclear conditions are consistent with warm gas (∼50 K) at surface column densities of 10^23 cm^-3 across 150 pc scales. One feature, extending from the northern bar end, resembles a leading spiral arm and is most likely a tidal feature (possibly connected to a small, gas-free satellite galaxy). The picture of a dynamically recent tidal interaction driving a nuclear gas inflow and starburst is consistent with current simulation studies of such phenomena.