Far-infrared emission from intergalactic medium in Stephan's Quintet
  revealed by AKARI
  The Stephan's Quintet (SQ, HCG92) was observed with the Far-Infrared Surveyor
(FIS) aboard AKARI in four far-infrared (IR) bands at 65, 90, 140, and 160 um.
The AKARI four-band images of the SQ show far-IR emission in the intergalactic
medium (IGM) of the SQ. In particular, the 160 um band image shows single peak
emission in addition to the structure extending in the North-South direction
along the shock ridge as seen in the 140 um band, H2 emission and X-ray
emission. Whereas most of the far-IR emission in the shocked region comes from
the cold dust component, shock-powered [CII]158um emission can significantly
contribute to the emission in the 160 um band that shows a single peak at the
shocked region. In the shocked region, the observed gas-to-dust mass ratio is
in agreement with the Galactic one. The color temperature of the cold dust
component (~20 K) is lower than that in surrounding galaxies (~30 K). We
discuss a possible origin of the intergalactic dust emission.
