THE BURIED STARBURST IN THE INTERACTING GALAXY II Zw 096 AS REVEALED BY THE SPITZER SPACE TELESCOPE

Inami, H.; Armus, L.; Surace, J. A.; Mazzarella, J. M.; Evans, A. S.; Sanders, D. B.; Howell, J. H.; Petric, A.; Vavilkin, T.; Iwasawa, K.; Haan, S.; Murphy, E. J.; Stierwalt, S.; Appleton, P. N.; Barnes, J. E.; Bothun, G.; Bridge, C. R.; Chan, B.; Charmandaris, V.; Frayer, D. T.; Kewley, L. J.; Kim, D. C.; Lord, S.; Madore, B. F.; Marshall, J. A.; Matsuhara, H.; Melbourne, J. E.; Rich, J.; Schulz, B.; Spoon, H. W. W.; Sturm, E.; U, V.; Veilleux, S.; Xu, K.
2010
ASTRONOMICAL JOURNAL
DOI
10.1088/0004-6256/140/1/63
An analysis of data from the Spitzer Space Telescope, Hubble Space Telescope, Chandra X-ray Observatory, and AKARI Infrared Astronomy Satellite is presented for the z = 0.036 merging galaxy system II Zw 096 (CGCG 448-020). Because II Zw 096 has an infrared luminosity of log(L-IR/L-circle dot) = 11.94, it is classified as a Luminous Infrared Galaxy (LIRG), and was observed as part of the Great Observatories All-sky LIRG Survey (GOALS). The Spitzer data suggest that 80% of the total infrared luminosity comes from an extremely compact, red source not associated with the nuclei of the merging galaxies. The Spitzer mid-infrared spectra indicate no high-ionization lines from a buried active galactic nucleus in this source. The strong detection of the 3.3 mu m and 6.2 mu m polycyclic aromatic hydrocarbon emission features in the AKARI and Spitzer spectra also implies that the energy source of II Zw 096 is a starburst. Based on Spitzer infrared imaging and AKARI near-infrared spectroscopy, the star formation rate is estimated to be 120 M-circle dot yr(-1) and >45 M-circle dot yr(-1), respectively. Finally, the high-resolution B-, I-, and H-band images show many star clusters in the interacting system. The colors of these clusters suggest at least two populations-one with an age of 1-5 Myr and one with an age of 20-500 Myr, reddened by 0-2 mag of visual extinction. The masses of these clusters span a range between 10(6) and 10(8) M-circle dot. This starburst source is reminiscent of the extranuclear starburst seen in NGC 4038/9 (the Antennae Galaxies) and Arp 299 but approximately an order of magnitude more luminous than the Antennae. The source is remarkable in that the off-nuclear infrared luminosity dominates the entire system.