Maffei 2 revealed: The infrared morphology of a hidden galaxy

We present near-infrared images in the J, H, and K bands of the starburst galaxy Maffei 2 taken with the NOAO Simultaneous Quad Infrared Imaging Device at Kitt Peak. These images reveal a morphology that is optically hidden by the ∼5 mag of visual extinction at its low galactic latitude (b= -0.3°). In the near-infrared, Maffei 2 can clearly be identified as a barred spiral of revised Hubble morphological type SBb(s) pec. The infrared extinction seen in the nucleus closely matches the known molecular morphology, indicating that such extinction can be a good tracer of molecular cloud complexes along density waves in galaxies. We infer peak extinctions of A_V∼ 10 mag, although there are indications the actual extinction may be higher due to saturation effects. There are a variety of peculiarities in the overall morphology of the galaxy including a misalignment of the NE and SW halves of the bar, an eastern spiral arm that is twice as long as the western arm, and an anomalous leading spiral arm seen just north of the NE bar end. These features are taken as indications of a recent interaction with a companion galaxy that could be responsible for producing the nuclear starburst. The anomalous northern arm is identified as a tidal tail that may possibly connect with an interacting dwarf galaxy at the end of the arm.