Tidal Disruption Events: Transient Astrophysical Laboratories
Nicholas Stone
Columbia University

Tidal disruption events (TDEs) arise when stars pass too close to supermassive black holes (SMBHs) in galactic nuclei. These rare events occur roughly once every 10,000 years in typical galactic nuclei, but produce powerful multiwavelength transients brighter than almost all supernovae. Our current sample of TDEs consists of a modest few dozen events, but will expand by orders of magnitude with upcoming time domain surveys. I will survey the broad potential these flares hold for measuring SMBH demographics, determining the bottom end of the SMBH mass function, and testing open questions in accretion physics. I will focus more, however, on my work to understand two observational surprises that have emerged from our current, more modestly sized TDE sample. First, an order unity fraction of TDE hosts are rare post-starburst (or "E+A") galaxies, which make up ~0.2% of all low redshift galaxies. Clearly, something very unusual is at play in the central parsecs of this galaxy class; a popular explanation is the presence of unresolved SMBH binaries, which may greatly elevate the TDE rate. My own theoretical work and analysis of HST archival data suggests a different explanation, one connected to the nature of star formation in a starburst galaxy. Second, the superficially low fraction of jetted, or relativistic, TDEs carries significant implications for black hole jet launching physics. I will discuss my recent work confirming a dearth of highly luminous jets in observed thermal TDEs, and its bearing on the search for "hidden variables" controlling relativistic jet power.