Origin of the dust emission from Tycho's SNR
  Aims: We investigate the spatial distribution of dust emission around Tycho's
SNR to understand its origin. We distinguish the dust associated with the SNR
from that of the surrounding ISM. Methods: We performed mid- to far-infrared
imaging observations of the remnant at wavelengths of 9, 15, 18, 24, 65, 90,
140, and 160um using the Infrared Camera and the Far-Infrared Surveyor onboard
AKARI. We compared the AKARI images with the Suzaku X-ray image and the 12CO
image of Tycho's SNR. Results: All the AKARI images except the 9, 140, and
160um band images show a shell-like emission structure with brightness peaks at
the north east (NE) and north west (NW) boundaries, sharply outlining part of
the X-ray shell. The 140 and 160um bands are dominated by cold dust emission
from the surrounding ISM near the NE boundary. Conclusion: We conclude that the
dust emission at the NE boundary comes from the ambient cloud interacting with
the shock front, while the origin of the dust emission at the NW boundary is
rather unclear because of the absence of prominent interstellar clouds near the
corresponding region. We cannot rule out the possibility that the latter is
mostly of an SN ejecta origin.
