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Mid-IR imaging of Toomre's Merger Sequence

V. Charmandaris·O. Laurent·I. F. Mirabel·P. Gallais
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Abstract

We present results on mid-IR (5--16micron) spectral imaging of a sequence of interacting galaxies, observed by ISOCAM. The galaxies are part of the well known Toomre's ``merger sequence'' which was defined as a sample of galaxies depicting progressive snapshots in the time evolution of a merging event. To trace the intensity of the radiation field in a starburst, we use the ratio of the 15 to 7 micron flux. Our analysis indicates that this ratio increases as galaxies move from the pre-starburst to the starburst phase and goes again down to ~1 in the post-starburst phase, a value typical of normal star forming regions in galactic disks. Moreover, we find that the variation of this ratio is well correlated with the one of the IRAS 25micron/12micron and 60micron/100micron flux ratios.

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V. Charmandaris, O. Laurent, I. F. Mirabel, P. Gallais. 1999-09-10. Mid-IR imaging of Toomre's Merger Sequence. https://arxiv.org/abs/astro-ph/9909186

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