RAPIDLY RISING TRANSIENTS IN THE SUPERNOVA-SUPERLUMINOUS SUPERNOVA GAP

• Published in: The Astrophysical journal Vol. 819; no. 1; pp. 35 - 56
• Main Authors: Arcavi, Iair, Wolf, William M., Howell, D. Andrew, Bildsten, Lars, Leloudas, Giorgos, Hardin, Delphine, Prajs, Szymon, Perley, Daniel A., Svirski, Gilad, Gal-Yam, Avishay, Katz, Boaz, McCully, Curtis, Cenko, S. Bradley, Lidman, Chris, Sullivan, Mark, Valenti, Stefano, Astier, Pierre, Balland, Cristophe, Carlberg, Ray G., Conley, Alex, Fouchez, Dominique, Guy, Julien, Pain, Reynald, Palanque-Delabrouille, Nathalie, Perrett, Kathy, Pritchet, Chris J., Regnault, Nicolas, Rich, James, Ruhlmann-Kleider, Vanina
• Format: Journal Article
• Language: English
• Published: Goddard Space Flight Center The American Astronomical Society 01.03.2016; American Astronomical Society
• Subjects: Absorption; Astrophysics; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; Constraining; COSMIC GAMMA BURSTS; Cosmology and Extra-Galactic Astrophysics; DIAGRAMS; Emission; EMISSION SPECTRA; Gamma ray bursts; H alpha line; High Energy Astrophysical Phenomena; HYDROGEN; Legacy; LUMINOSITY; MAGNETIC STARS; NEUTRON STARS; PHASE SPACE; Physics; Sciences of the Universe; SILICON IONS; Spectral emissivity; STELLAR WINDS; SUPERNOVAE; supernovae: individual (PTF10iam, SNLS04D4ec, SNLS05D2bk, SNLS06D1hc, Dougie); TRANSIENTS; VELOCITY; VISIBLE RADIATION; WHITE DWARF STARS; Snls06d1hc; Snls04d4ec; Snls05d2bk; Supernovae: Individual (ptf10iam; Dougie
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/0004-637X/819/1/35

ABSTRACT We present observations of four rapidly rising (trise 10 days) transients with peak luminosities between those of supernovae (SNe) and superluminous SNe (Mpeak −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 H emission, but an unusual absorption feature, which can be interpreted as either high velocity H (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.