Research Interests

During the past decade, I have conducted the world's most successful search for relatively nearby supernovae (SNe) using my robotic telescope at Lick Observatory. My research on SNe (a) showed that many core-collapse SNe result from massive stars with partially or highly stripped envelopes, (b) helped establish the Type IIn subclass characterized by ejecta interacting with circumstellar gas, (c) observationally identified the progenitors of some SNe, (d) revealed that many SNe are quite aspherical, and (e) showed that Type Ia supernovae (SNe Ia) exhibit considerable heterogeneity. This last point was crucial to the development of methods to calibrate SNe Ia for accurate distance determinations. I was a key member of two teams that used high-redshift SNe Ia to discover the accelerating expansion of the Universe, driven by mysterious "dark energy." My early work showed that the nuclei of most bright, nearby galaxies exhibit activity physically similar to that of quasars, driven by gas accretion onto a supermassive black hole (BH). I contributed to the discovery of the fundamental relationship between central BH mass and galaxy bulge luminosity (and velocity dispersion). In about six X-ray binary stars, I provided compelling dynamical evidence for a stellar-mass BH. Recently, my robotic telescope made some of the earliest measurements of the optical afterglows of gamma-ray bursts.

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Primary Section

Section 12: Astronomy

Secondary Section

Section 13: Physics