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This thesis reports the discovery of relativistic stellar explosions outside of the gamma ray band, using optical time domain surveys. It is well known that some massive stars end their lives with the formation of a compact object (a neutron star or black hole) that launches a relativistic jet detectable from earth as a burst of gamma rays. It has long been suspected, however, that gamma ray bursts are only the tip of the iceberg in a broad landscape of relativistic explosions, and so the results presented in this thesis represent a major breakthrough. Highlights of this thesis include: characterization of the first major new class of relativistic explosions in a decade; the discovery of abrupt end-of-life mass-loss in a surprisingly diverse range of stars; and the routine discovery of afterglow emission and several events that may represent baryonically dirty jets or jets viewed slightly off axis. These discoveries necessitated the solution of difficult technical challenges such as the identification of rare and fleeting "needles" in a vast haystack of time-varying phenomena in the night sky, and responding to discoveries within hours to obtain data across the electromagnetic spectrum from X-rays to radio wavelengths.
List of contents
Chapter1: Introduction and Summary.- Chapter2: ZTF20aajnksq (AT 2020blt): A Fast Optical Transient at I 2•9
With No Detected Gamma-Ray Burst Counterpart.- Chapter3: iPTF Archival Search for Fast Optical Transients.- Chapter4: SN 2020bvc: a Broad-lined Type Ic Supernova with a Doublepeaked Optical Light Curve and a Luminous X-ray and Radio Counterpart.- Chapter5: The Broad-lined Ic Supernova ZTF18aaqjovh (SN 2018bvw): An Optically Discovered Engine-driven Supernova Candidate with Luminous Radio Emission.- Chapter6: Evidence for Late-stage Eruptive Mass Loss in the Progenitor to SN 2018gep, a Broad-lined Ic Supernova: Pre-explosion Emission and a Rapidly Rising Luminous Transient.- Chapter7: AT2018cow: A Luminous Millimeter Transient. Chapter8: TheKoala: AFast Blue Optical Transient with Luminous Radio Emission from a Starburst Dwarf Galaxy at I = 0•27.- Chapter9: Other Contributions.- Chapter10: TheFuture.
About the author
Anna Y. Q. Ho is an assistant professor of astronomy at Cornell University.
