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A Study of the Distribution of Star-Forming Regions in Luminous Infrared Galaxies by Means of H$α$ Imaging Observations

T. Hattori·M. Yoshida·H. Ohtani·H. Sugai·T. Ishigaki·M. Sasaki·T. Hayashi·S. Ozaki·M. Ishii·A. Kawai
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Abstract

We performed H-alpha imaging observations of 22 luminous infrared galaxies to investigate how the distribution of star-forming regions in these galaxies is related to galaxy interactions. Based on correlation diagrams between H-alpha flux and continuum emission for individual galaxies, a sequence for the distribution of star-forming regions was found: very compact (~100 pc) nuclear starbursts with almost no star-forming activity in the outer regions (type 1), dominant nuclear starbursts < 1 kpc in size and a negligible contribution from the outer regions (type 2), nuclear starbursts > 1 kpc in size and a significant contribution from the outer regions (type 3), and extended starbursts with relatively faint nuclei (type 4). These classes of star-forming region were found to be strongly related to global star-forming properties such as star-formation efficiency, far-infrared color, and dust extinction. There was a clear tendency for the objects with more compact distributions of star-forming regions to show a higher star-formation efficiency and hotter far-infrared color. An appreciable fraction of the sample objects were dominated by extended starbursts (type 4), which is unexpected in the standard scenario of interaction-induced starburst galaxies. We also found that the distribution of star-forming regions was weakly but clearly related to galaxy morphology: severely disturbed objects had a more concentrated distribution of star-forming regions. This suggests that the properties of galaxy interactions, such as dynamical phase and orbital parameters, play a more important role than the internal properties of progenitor galaxies, such as dynamical structure or gas mass fraction. We also discuss the evolution of the distribution of star-forming regions in interacting galaxies.

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T. Hattori, M. Yoshida, H. Ohtani, H. Sugai, T. Ishigaki, M. Sasaki, T. Hayashi, S. Ozaki, M. Ishii, A. Kawai. 2003-11-07. A Study of the Distribution of Star-Forming Regions in Luminous Infrared Galaxies by Means of H$α$ Imaging Observations. https://doi.org/10.1086/381060

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