A high angular resolution search for the progenitor of the Type Ic supernova 2004gt

We report the results of a high spatial resolution search for the progenitor of Type Ic supernova SN 2004gt, using the newly commissioned Keck laser guide star adaptive optics (LGSAO) system along with archival Hubble Space Telescope data. This is the deepest search yet performed for the progenitor of any Type Ib/c event in a wide wavelength range stretching from the far-UV to the near-IR. We determine that the progenitor of SN 2004gt was most likely less luminous than M_v = -5.5 mag and M_B = -6.5 mag. The massive stars exploding as hydrogen-deficient core-collapse supernovae should have lost their outer hydrogen envelopes prior to their explosion, either through winds - such stars are identified within our Galaxy as Wolf-Rayet (W-R) stars - or to a binary companion. The luminosity limits we set rule out more than half of the known Galactic W-R stars as possible progenitors of this event. In particular, they imply that a W-R progenitor should have been among the more evolved (highly stripped, less luminous) of these stars, a concrete constraint on its evolutionary state just prior to core collapse. The possibility of a less luminous, lower mass binary progenitor cannot be constrained. This study demonstrates the power of LGS observations in furthering our understanding of core collapse and the physics powering supernovae, gamma-ray bursts, and X-ray flashes.