Large-scale distributions of mid- and far-infrared emission from the
  center to the halo of M82 revealed with AKARI
  The edge-on starburst galaxy M82 exhibits complicated distributions of
gaseous materials in its halo, which include ionized superwinds driven by
nuclear starbursts, neutral materials entrained by the superwinds, and
large-scale neutral streamers probably caused by a past tidal interaction with
M81. We investigate detailed distributions of dust grains and polycyclic
aromatic hydrocarbons (PAHs) around M82 to understand their interplay with the
gaseous components. We performed mid- (MIR) and far-infrared (FIR) observations
of M82 with the Infrared Camera and Far-Infrared Surveyor on board AKARI. We
obtain new MIR and FIR images of M82, which reveal both faint extended emission
in the halo and very bright emission in the center with signal dynamic ranges
as large as five and three orders of magnitude for the MIR and FIR,
respectively. We detect MIR and FIR emission in the regions far away from the
disk of the galaxy, reflecting the presence of dust and PAHs in the halo of
M82. We find that the dust and PAHs are contained in both ionized and neutral
gas components, implying that they have been expelled into the halo of M82 by
both starbursts and galaxy interaction. In particular, we obtain a tight
correlation between the PAH and H$\alpha$ emission, which provides evidence
that the PAHs are well mixed in the ionized superwind gas and outflowing from
the disk.
