Two superluminous supernovae from the early universe discovered by the supernova legacy survey
- Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Goleta, CA 93117 (United States)
- Departments of Physics and Astronomy, University of California, Berkeley, Berkeley, CA 94720-7300 (United States)
- Australian Astronomical Observatory, P.O. Box 915, North Ryde, NSW 1670 (Australia)
- School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom)
- Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309-389 (United States)
- LPNHE, CNRS-IN2P3 and University of Paris VI and VII, F-75005 Paris (France)
- Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H8 (Canada)
- CPPM, CNRS-IN2P3 and University Aix Marseille II, Case 907, F-13288 Marseille Cedex 9 (France)
- DSM/IRFU/SPP, CEA-Saclay, F-91191 Gif-sur-Yvette (France)
- DRDC Ottawa, 3701 Carling Avenue, Ottawa, ON K1A 0Z4 (Canada)
- Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, Victoria, BC V8W 3P6 (Canada)
We present spectra and light curves of SNLS 06D4eu and SNLS 07D2bv, two hydrogen-free superluminous supernovae (SNe) discovered by the Supernova Legacy Survey. At z = 1.588, SNLS 06D4eu is the highest redshift superluminous SN with a spectrum, at M{sub U} = –22.7 it is one of the most luminous SNe ever observed, and it gives a rare glimpse into the rest-frame ultraviolet where these SNe put out their peak energy. SNLS 07D2bv does not have a host galaxy redshift, but on the basis of the SN spectrum, we estimate it to be at z ∼ 1.5. Both SNe have similar observer-frame griz light curves, which map to rest-frame light curves in the U band and UV, rising in ∼20 rest-frame days or longer and declining over a similar timescale. The light curves peak in the shortest wavelengths first, consistent with an expanding blackbody starting near 15,000 K and steadily declining in temperature. We compare the spectra with theoretical models, and we identify lines of C II, C III, Fe III, and Mg II in the spectra of SNLS 06D4eu and SCP 06F6 and find that they are consistent with an expanding explosion of only a few solar masses of carbon, oxygen, and other trace metals. Thus, the progenitors appear to be related to those suspected for SNe Ic. A high kinetic energy, 10{sup 52} erg, is also favored. Normal mechanisms of powering core-collapse or thermonuclear SNe do not seem to work for these SNe. We consider models powered by {sup 56}Ni decay and interaction with circumstellar material, but we find that the creation and spin-down of a magnetar with a period of 2 ms, a magnetic field of 2 × 10{sup 14} G, and a 3 M {sub ☉} progenitor provides the best fit to the data.
- OSTI ID:
- 22348481
- Journal Information:
- Astrophysical Journal, Vol. 779, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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