The High-metallicity Explosion Environment of the Relativistic Supernova 2009bb

E. M. Levesque (1,2), A. M. Soderberg (2,18), R. J. Foley (2,19), E. Berger (2), L. J. Kewley (1), S. Chakraborti (3), A. Ray (3), M. A. P. Torres (2), P. Challis (2), R. P. Kirshner (2), S. D. Barthelmy (4), M. F. Bietenholz (5,6), P. Chandra (7), V. Chaplin (8), R. A. Chevalier (9), N. Chugai (10), V. Connaughton (8), A. Copete (2), O. Fox (9), C. Fransson (11), J. E. Grindlay (2), M. A. Hamuy (12), P. A. Milne (13), G. Pignata (12,14), M. D. Stritzinger (15,16) and M. H. Wieringa (17)

1 Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA
2 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-51, Cambridge, MA 02138, USA
3 Tata Institute of Fundamental Research, Mumbai 400 005, India
4 NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
5 Department of Physics and Astronomy, York University, Toronto, ON M3J 1P3, Canada
6 Hartebeestehoek Radio Observatory, P.O. Box 443, Krugersdorp 1740, South Africa
7 Royal Military College of Canada, Kingston, ON K7K 784, Canada
8 University of Alabama, Huntsville, AL 35899, USA
9 University of Virginia, Department of Astronomy, P.O. Box 400325, Charlottesville, VA 22904, USA
10 Institute of Astronomy, RAS, Pyatnitskaya 48, Moscow 119017, Russia
11 Department of Astronomy, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
12 Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago, Chile
13 Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA
14 Departamento de Ciencias Fisicas, Universidad Andres Bello, Avda. Republica 252, Santiago, Chile
15 Las Campanas Observatory, Carnegie Observatories, Casilla 601, La Serena, Chile
16 Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
17 Australia Telescope National Facility, CSIRO, Epping 2121, Australia
18 Hubble Fellow
19 Clay Fellow

We investigate the environment of the nearby (d ≈ 40 Mpc) broad-lined Type Ic supernova (SN) 2009bb. This event was observed to produce a relativistic outflow likely powered by a central accreting compact object. While such a phenomenon was previously observed only in long-duration gamma-ray bursts (LGRBs), no LGRB was detected in association with SN 2009bb. Using an optical spectrum of the SN 2009bb explosion site, we determine a variety of interstellar medium properties for the host environment, including metallicity, young stellar population age, and star formation rate. We compare the SN explosion site properties to observations of LGRB and broad-lined SN Ic host environments on optical emission line ratio diagnostic diagrams. Based on these analyses, we find that the SN 2009bb explosion site has a metallicity between 1.7 Z sun and 3.5 Z sun, in agreement with other broad-lined SN Ic host environments and at odds with the low-redshift LGRB host environments and recently proposed maximum metallicity limits for relativistic explosions. We consider the implications of these findings and the impact that SN 2009bb's unusual explosive properties and environment have on our understanding of the key physical ingredient that enables some SNe to produce a relativistic outflow.

Reference: 2010 ApJ 709 L26
Status: Manuscript has been accepted