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AKARI observations of the multiphase intergalactic medium of Stephan's Quintet

Published online by Cambridge University Press:  17 August 2012

Toyoaki Suzuki
Affiliation:
Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3–1–1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252–5210, Japan email: [email protected]
Hidehiro Kaneda
Affiliation:
Graduate School of Science, Nagoya University, Furu-cho, Chikusa-ku, Nagoya 464–8602, Japan
Takashi Onaka
Affiliation:
Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
Tetsu Kitayama
Affiliation:
Department of Physics, Toho University, Funabashi, Chiba 274-8510, Japan
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Abstract

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Stephan's Quintet (SQ, HCG92) is a well studied compact group of galaxies with a disturbed intergalactic medium (IGM). An “intruder” galaxy NGC 7318b is currently colliding with the IGM at a relative velocity of 1000 km s−1, causing a large-scale shock front. We observed SQ with the Far-Infrared Surveyor (FIS) aboard AKARI in four far-infrared (far-IR) bands at 65, 90, 140, and 160μm. The 160μm image clearly shows an additional peak of emission overlying structure extending in the North-South direction along the shock ridge seen in the 140μm band, and in H2 and X-ray emission. Whereas most of the far-IR emission in the shocked region is from cold dust (20 K), the [CII]158μm emission - whose luminosity is comparable to that of the warm H2 gas - can significantly contribute to the single peak emission in the 160μm band. We conclude that the [CII] line emission comes from the warm H2 gas in the shock. Our result represents the first detection of shock-excited [CII] line emission.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2012

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