Discovery of Molecular Gas in the Outflow and Tidal Arms around M82

We present the first fully sampled map of 12CO (1-0) emission from M82 covering the entire galaxy. Our map contains an ~12 × 15 kpc2 area. We find that extraplanar CO emission, previously reported at short distances above the galactic plane, extends to heights of up to 6 kpc above the disk. Some of this emission is associated with tidal arms seen in H I, implying either that M82 contained substantial amounts of molecular gas in the outer disk or that molecular gas formed after the tidal features. CO emission along the direction of the outflow extends to distances of ~3 kpc above and below the disk. At this distance, the line is shifted in velocity ~100 km s-1 and has the same sense as the galactic outflow from the central starburst. This implies that molecular gas may be entrained into the outflow