A High Angular Resolution Search for the Progenitor of the Type Ic Supernova 2004gt

We report the results of a high-spatial-resoltion search for the progenitorof type Ic supernova SN 2004gt, using the newly commissioned Keck laser-guidestar adaptive optics system (LGSAO) along with archival Hubble Space Telescopedata. This is the deepest search yet performed for the progenitor of any typeIb/c event in a wide wavelength range stretching from the far UV to the nearIR. We determine that the progenitor of SN 2004gt was most likely less luminousthan M_V=-5.5 and M_B=-6.5 magnitudes. The massive stars exploding ashydrogen-deficient core-collapse supernovae (SNe) should have lost their outerhydrogen envelopes prior to their explosion, either through winds -- such starsare identified within our Galaxy as Wolf-Rayet (W-R) stars -- or to a binarycompanion. The luminosity limits we set rule out more than half of the knowngalactic W-R stars as possible progenitors of this event. In particular, theyimply that a W-R progenitor should have been among the more-evolved (highlystripped, less luminous) of these stars, a concrete constraint on itsevolutionary state just prior to core collapse. The possibility of a lessluminous, lower-mass binary progenitor cannot be constrained. This studydemonstrates the power of LGS observations in furthering our understanding ofcore collapse, and the physics powering supernovae, GRBs and XRFs.