Constraints on the Progenitor of SN 2016gkg From Its Shock-Cooling Light Curve
astro-ph.HE
/ Authors
Iair Arcavi, Griffin Hosseinzadeh, Peter J. Brown, Stephen J. Smartt, Stefano Valenti, Leonardo Tartaglia, Anthony L. Piro, Jose L. Sanchez, Brent Nicholls, Berto L. A. G. Monard
and 10 more authors
D. Andrew Howell, Curtis McCully, David J. Sand, John Tonry, Larry Denneau, Brian Stalder, Ari Heinze, Armin Rest, Ken W. Smith, David Bishop
/ Abstract
SN 2016gkg is a nearby Type IIb supernova discovered shortly after explosion. Like several other Type IIb events with early-time data, SN 2016gkg displays a double-peaked light curve, with the first peak associated with the cooling of a low-mass extended progenitor envelope. We present unprecedented intranight-cadence multi-band photometric coverage of the first light-curve peak of SN 2016gkg obtained from the Las Cumbres Observatory Global Telescope network, the Asteroid Terrestrial-impact Last Alert System, the Swift satellite and various amateur-operated telescopes. Fitting these data to analytical shock-cooling models gives a progenitor radius of ~25-140 solar radii with ~2-30 x 10^-2 solar masses of material in the extended envelope (depending on the model and the assumed host-galaxy extinction). Our radius estimates are broadly consistent with values derived independently (in other works) from HST imaging of the progenitor star. However, the shock-cooling model radii are on the lower end of the values indicated by pre-explosion imaging. Hydrodynamical simulations could refine the progenitor parameters deduced from the shock-cooling emission and test the analytical models.