Multiwavelength Diagnostics of a Late-stage Galaxy Merger Sequence
Abstract
We discuss the evolutionary state of five gas-rich early-type galaxies (ETGs) whose integrated properties suggest that these systems are mid-to-late stage minor mergers, extending beyond the Toomre sequence. A variety of multiwavelength data are utilized to explore diagnostics of the merger process, including imaging photometry derived from observations with GALEX, SDSS, WISE and Spitzer. In particular, we interpret mid-infrared spectra (5-14 microns) obtained with the Infrared Spectrograph on Spitzer. Unusual for ETGs, we find strong emission from polycyclic aromatic hydrocarbons bands and singly-ionized atomic lines, likely caused by low-level star formation in these systems. The overall strength of the PAH emission appears correlated with morphologically signatures of the time since the merger/accretion event. We present feature strengths and ratios derived from the mid-infrared spectra together with star formation rate estimates using GALEX FUV and Spitzer 24 micron continuum data to intrepret the stellar content and history for this sample.
- Publication:
-
American Astronomical Society Meeting Abstracts #221
- Pub Date:
- January 2013
- Bibcode:
- 2013AAS...22143408F