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Astron. Astrophys. 362, 97-104 (2000)

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On the degree of dust extinction in major galaxy mergers with dusty starburst

K. Bekki 1 and Y. Shioya 2

1 Division of Theoretical Astrophysics, National Astronomical Observatory, Mitaka, Tokyo, 181-8588, Japan (bekki@th.nao.ac.jp)
2 Astronomical Institute, Tohoku University, Sendai, 980-8578, Japan (shioya@astr.tohoku.ac.jp)

Received 28 April 2000 / Accepted 8 August 2000


We numerically investigate how fundamental properties of the spectral energy distribution (SED) of a major gas-rich galaxy merger with dusty starburst are determined by the initial orbital configuration of the merger. We found that an infrared luminous galaxy with dusty starburst formed by a nearly retrograde-retrograde merger suffers the most remarkable dust extinction of stellar light and consequently shows very red colours. Considering that a retrograde-retrograde merger does not produce strong and long tidal tails, this result suggests that a luminous infrared galaxy without clear signs of interaction and merging shows very large internal dust extinction and redder colours. These numerical results furthermore imply that the morphology of a luminous infrared galaxy can correlate with the degree of internal dust extinction and thus with the shape of the SED, principally because the morphology of a merger also depends strongly on the initial orbital configuration of the merger. Based on these results, we discuss the origin of ultra-luminous infrared galaxies.

Key words: galaxies: interactions – galaxies: ISM – galaxies: kinematics and dynamics

Send offprint requests to: K. Bekki

© European Southern Observatory (ESO) 2000

Online publication: October 30, 19100