EVIDENCE FOR A COMPACT WOLF-RAYET PROGENITOR FOR THE TYPE Ic SUPERNOVA PTF 10vgv

We present the discovery of PTF 10vgv, a Type Ic supernova detected by the\nPalomar Transient Factory, using the Palomar 48-inch telescope (P48). R-band\nobservations of the PTF 10vgv field with P48 probe the supernova emission from\nits very early phases (about two weeks before R-band maximum), and set limits\non its flux in the week prior to the discovery. Our sensitive upper limits and\nearly detections constrain the post-shock-breakout luminosity of this event.\nVia comparison to numerical (analytical) models, we derive an upper-limit of R\n\\lesssim 4.5 Rsun (R \\lesssim 1 Rsun) on the radius of the progenitor star, a\ndirect indication in favor of a compact Wolf-Rayet star. Applying a similar\nanalysis to the historical observations of SN 1994I, yields R \\lesssim 1/4 Rsun\nfor the progenitor radius of this supernova.\n