Warm Molecular Hydrogen in the Galactic Wind of M82

We report the detection of a complex of extraplanar warm H 2 knots and filaments extending more than ∼3 kpc above and below the galactic plane of M82, roughly coincident with the well-known galactic wind in this system. Comparisons of these data with published results at other wavelengths provide quantitative constraints on the topology, excitation, heating, and stability against disruption of the wind-entrained molecular interstellar matter in this prototypical galactic wind. Deep H 2 2.12 μm observations such as these represent a promising new method to study the elusive but potentially important molecular component of galactic winds.