Open Access Honors Program Thesis


Galaxies--Evolution; Galaxies--Clusters;


We discuss an optical study of a triple galaxy system at a redshift of 0.06. In optical images from Data Release 7 of the Sloan Digital Sky Survey (SDSS), 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. One of the the pair and the more isolated galaxy are low-luminosity radio sources. The lone galaxy appears 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 have acquired deep spatially resolved optical (3500-8500 ˚A) spectroscopy with the Sparsepak integral field unit and the Bench Spectrograph on the WIYN 3.5-meter telescope. Both the pair and the more isolated galaxy show post-starburst (K+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 that potentially indicate the presence of an active galactic nucleus (AGN). The goals of this study include a better understanding of the connection between, and relative timing of, galaxy interactions and the triggering of star formation and an active galactic nucleus.

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University Honors Designation

A thesis submitted in partial fulfillment of the requirements for the designation University Honors

Date Original


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