Mid-Infrared Images of Luminous Infrared Galaxies in a Merging Sequence
Abstract
We report mid-infrared observations of several luminous infrared galaxies (LIGs) carried out with the Infrared Space Observatory. Our sample was chosen to represent different phases of a merger sequence of galaxy-galaxy interaction with special emphasis on early/intermediate stages of merging. The mid-infrared emission of these LIGs shows extended structures for the early and intermediate mergers, indicating that most of the mid-infrared luminosities are not from a central active galactic nucleus. Both the infrared hardness (indicated by the IRAS 12, 25, and 60 μm flux density ratios) and the peak-to-total flux density ratios of these LIGs increase as projected separation of these interacting galaxies become smaller, consistent with increasing star formation activities that are concentrated to a smaller area as the merging process advances. These observations provide among the first observational constraint of largely theoretically based scenarios.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 1999
- DOI:
- 10.1086/311839
- arXiv:
- arXiv:astro-ph/9812476
- Bibcode:
- 1999ApJ...511L..17H
- Keywords:
-
- GALAXIES: INDIVIDUAL: NAME: ARP 302;
- GALAXIES: INDIVIDUAL: NGC NUMBER: NGC 6670;
- GALAXIES: INDIVIDUAL: ALPHANUMERIC: UGC 2369;
- GALAXIES: INDIVIDUAL: NGC NUMBER: NGC 7592;
- GALAXIES: INDIVIDUAL: NGC NUMBER: NGC 5256;
- GALAXIES: INDIVIDUAL: NAME: MARKARIAN 848;
- GALAXIES: INDIVIDUAL: NGC NUMBER: NGC 6090;
- GALAXIES: INTERACTIONS;
- GALAXIES: STARBURST;
- INFRARED: GALAXIES;
- Galaxies: Individual: Name: Arp 302;
- Galaxies: Individual: NGC Number: NGC 6670;
- Galaxies: Individual: Alphanumeric: UGC 2369;
- Galaxies: Individual: NGC Number: NGC 7592;
- Galaxies: Individual: NGC Number: NGC 5256;
- Galaxies: Individual: Name: Markarian 848;
- Galaxies: Individual: NGC Number: NGC 6090;
- Galaxies: Interactions;
- Galaxies: Starburst;
- Infrared: Galaxies;
- Astrophysics
- E-Print:
- 10 pages, 3 figures, please refer to ApJ Letters for the final version