The Buried Starburst in the Interacting Galaxy II Zw 096 as Revealed by the Spitzer Space Telescope
Hanae Inami
(1)
,
Lee Armus
(1)
,
Jason A. Surace
(1)
,
Joseph M. Mazzarella
(2)
,
Aaron S. Evans
(3)
,
David B. Sanders
(4)
,
Justin H. Howell
(1)
,
Andreea Petric
(1)
,
Tatjana Vavilkin
(5)
,
K. Iwasawa
(6)
,
Sebastian Haan
(1)
,
E. J. Murphy
(1)
,
Sabrina Stierwalt
(1)
,
Philip N. Appleton
(7)
,
J. E. Barnes
(4)
,
Greg Bothun
(8)
,
C. R. Bridge
(9)
,
B. Chan
(2)
,
Vassilis Charmandaris
(10, 11)
,
David T. Frayer
(7)
,
Lisa J. Kewley
(4)
,
Dong-Chan Kim
(3)
,
Steven D. Lord
(2)
,
Barry F. Madore
(2)
,
J. A. Marshall
(1)
,
Hideo Matsuhara
(12)
,
J. E. Melbourne
(9)
,
James Rich
(4)
,
B. Schulz
(7)
,
Henrik W. W. Spoon
(13)
,
Eckhard Sturm
(14)
,
V. U
(4)
,
Sylvain Veilleux
(15)
,
Kevin Xu
(7)
1
SSC -
Spitzer Science Center, California Institute of Technology
2 IPAC - Infrared Processing Analysis Center, California Institute of Technology
3 NRAO - National Radio Astronomy Observatory [Charlottesville]
4 Institute for Astronomy, University of Hawaii
5 Department of Physics and Astronomy, SUNY Stony Brook
6 UB - Universitat de Barcelona
7 NHSC - NASA Herschel Science Center, California Institute of Technology
8 Department of Physics, University of Oregon
9 Cahill Center for Astronomy and Astrophysics
10 Crete Center for Theoretical Physics, Department of Physics
11 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
12 ISAS - Institute of Space and Astronautical Science
13 Department of Astronomy, Cornell University
14 MPE - Max-Planck-Institut für Extraterrestriche Physik
15 Department of Astronomy, University of Maryland
2 IPAC - Infrared Processing Analysis Center, California Institute of Technology
3 NRAO - National Radio Astronomy Observatory [Charlottesville]
4 Institute for Astronomy, University of Hawaii
5 Department of Physics and Astronomy, SUNY Stony Brook
6 UB - Universitat de Barcelona
7 NHSC - NASA Herschel Science Center, California Institute of Technology
8 Department of Physics, University of Oregon
9 Cahill Center for Astronomy and Astrophysics
10 Crete Center for Theoretical Physics, Department of Physics
11 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
12 ISAS - Institute of Space and Astronautical Science
13 Department of Astronomy, Cornell University
14 MPE - Max-Planck-Institut für Extraterrestriche Physik
15 Department of Astronomy, University of Maryland
Résumé
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 sun) = 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 mum and 6.2 mum 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 sun yr-1 and >45 M sun 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 106 and 108 M sun. 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.