Analysis of Radio and Optical Data on a Triple Galaxy Merger System
American Astronomical Society, AAS Meeting #221, #147.12
Published in Jan 2013
We discuss a radio and optical study of a triple galaxy system at a redshift of 0.06. In optical images from the SDSS Data Release 7, the system consists of a close pair plus another galaxy at a projected distance of 35 kpc. Tidal features extending at least 30 kpc are visible to the southeast of both the galaxy pair and the third member of the system, suggesting significant interaction. Both the pair and the more isolated galaxy are low-luminosity radio sources. The lone galaxy is extended in a radio map from the FIRST survey. If the radio emission arises from ongoing star formation, the implied star formation rates are 1 to 2 solar masses per year in each source. We are analyzing new radio data to help determine whether the emission source is indeed star formation or whether one or both sources are low-luminosity AGN; we have found low-luminosity radio AGN in similar systems. We have also acquired deep spatially resolved optical (3500 - 8500 Angstroms) spectroscopy with the Sparsepak integral field unit on the WIYN 3.5-meter telescope. Both the pair and the more isolated galaxy show post-starburst (E+A) spectral signatures, and stellar population synthesis using Bruzual and Charlot (2003) models indicate that all components of the triple system had episodes of significant star formation at comparable times in the past. This system is part of a larger study of post-starburst galaxies which host radio sources, whose goals include a better understanding of the connection between, and relative timing of, galaxy interactions and the triggering of star formation and AGN. This work was partially supported by the National Science Foundation's REU program through NSF Award AST-1004881.
(c) 2013: American Astronomical Society