Optical and Infrared Morphologies of Local Luminous Infrared Galaxies
Abstract
Luminous and Ultra-luminous infrared galaxies (LIRGs and ULIRGs) are a mixture of advanced mergers, interacting systems, and single galaxies. In order to better understand the role of galaxy interactions on star formation,luminosity, and other galaxy properties, we have developed a visual morphological classification scheme for galaxies that fully accounts for all possible interactions seen in local LIRGs. We have also refined the methods for automated galaxy classification by carefully selecting the galaxy pixel members using a surface brightness algorithm. Major galaxy interactions are clearly a driving force in the increased infrared luminosity of local galaxies, however, below an infrared luminosity of 1011.5L⊙ minor mergers and secular processes dominate. We empirically derive a separation between merging and non-merging galaxies using automatic classification parameters. Furthermore, the M20 parameter separates galaxies into different merger stages. Our new deep Spitzer 3.6 and 4.5 μm observations of 202 local LIRGs and ULIRGs reveal large stellar debris fields that extend up to 100 kpc around the galaxies and contain 5 to 15% of the total galaxy flux. We analyzed the mass and structure of extended infrared emission and show that the infrared stellar debris fields around the galaxies build up throughout the merging process.
- Publication:
-
American Astronomical Society Meeting Abstracts #225
- Pub Date:
- January 2015
- Bibcode:
- 2015AAS...22513103L