RAPIDLY RISING TRANSIENTS IN THE SUPERNOVA—SUPERLUMINOUS SUPERNOVA GAP
- Las Cumbres Observatory Global Telescope, 6740 Cortona Dr., Suite 102, Goleta, CA 93111 (United States)
- Department of Physics, University of California, Santa Barbara, CA 93106 (United States)
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106 (United States)
- Department of Particle Physics and Astrophysics, The Weizmann Institute of Science, Rehovot, 76100 (Israel)
- LPNHE, CNRS-IN2P3 and University of Paris VI and VII, F-75005 Paris (France)
- School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom)
- Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark)
- Racah Institute for Physics, The Hebrew University, Jerusalem 91904 (Israel)
- Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States)
- Australian Astronomical Observatory, P.O. Box 915, North Ryde, NSW 1670 (Australia)
- Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H8 (Canada)
- Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309-389 (United States)
We present observations of four rapidly rising (t{sub rise} ≈ 10 days) transients with peak luminosities between those of supernovae (SNe) and superluminous SNe (M{sub peak} ≈ −20)—one discovered and followed by the Palomar Transient Factory (PTF) and three by the Supernova Legacy Survey. The light curves resemble those of SN 2011kl, recently shown to be associated with an ultra-long-duration gamma-ray burst (GRB), though no GRB was seen to accompany our SNe. The rapid rise to a luminous peak places these events in a unique part of SN phase space, challenging standard SN emission mechanisms. Spectra of the PTF event formally classify it as an SN II due to broad Hα emission, but an unusual absorption feature, which can be interpreted as either high velocity Hα (though deeper than in previously known cases) or Si ii (as seen in SNe Ia), is also observed. We find that existing models of white dwarf detonations, CSM interaction, shock breakout in a wind (or steeper CSM), and magnetar spin down cannot readily explain the observations. We consider the possibility that a “Type 1.5 SN” scenario could be the origin of our events. More detailed models for these kinds of transients and more constraining observations of future such events should help to better determine their nature.
- OSTI ID:
- 22521486
- Journal Information:
- Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 819; ISSN ASJOAB; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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