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Published May 2015 | Published
Journal Article Open

The Spitzer Interacting Galaxies Survey: A Mid-infrared Atlas of Star Formation

Abstract

The Spitzer Interacting Galaxies Survey is a sample of 103 nearby galaxies in 48 systems, selected using association likelihoods and therefore free from disturbed morphology biases. All galaxies have been observed with Infrared Array Camera and MIPS 24 μm bands from the Spitzer Space Telescope. This catalog presents the global flux densities and colors of all systems and correlations between the interacting systems and their specific star formation rate (sSFR). This sample contains a wide variety of galaxy interactions with systems ranging in mass, mass ratios, and gas-content as well as interaction strength. This study seeks to identify the process of triggering star formation in galaxy interactions, therefore, we focus on the non-active galactic nucleus spiral galaxies only. From this subset of 70 spiral galaxies we have determined that this sample has enhanced sSFR compared to a sample of non-interacting field galaxies. Through optical data we have classified each system by "interaction strength"; the strongly interacting (Stage 4) galaxies have higher sSFR values than the weakly (Stage 2) and moderately (Stage 3) interacting systems. However, the Stage 2 and 3 systems have statistically identical sSFR properties, despite the lack of optical interaction signatures exhibited by the Stage 2 galaxies. We suggest that the similarity of sSFR in these stages could be a consequence of some of these Stage 2 systems actually being post-perigalactic and having had sufficient time for their tidal features to fade to undetectable levels. This interpretation is consistent with the correlation of sSFR with separation, which we have determined to have little variation up to 100 kpc.

Additional Information

© 2015 American Astronomical Society. Received 2014 May 29; accepted 2015 January 20; published 2015 May 6. We would like to thank the referee for useful comments which have improved our paper. This work makes use of observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. This work is based in part on the IRAC post-BCD processing software "IRACproc" developed by Mike Schuster, Massimo Marengo, and Brian Patten at the Smithsonian Astrophysical Observatory. We acknowledge support in part from NASA grant NNX10AD68G, NASA JPL RSA 1369566, and NASA JPL RSA 717352. N.J.B. would like to thank the physics department at the University of Crete and IESL Foundation for Research and Technology for their hospitality during part of this work.

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