Tidal Disruption Events: A New Black Hole Census

Tidal disruption events, or TDEs, occur when stars pass too close to massive black holes (MBHs) and are spaghettified by tidal forces. The ensuing fallback of stellar debris powers a luminous flare brighter than most supernovae, with most of the luminosity emerging as quasi-thermal optical, UV, and soft X-rays. These transients have great potential to measure the demographics of MBHs in the Universe, especially at the uncertain bottom end of the MBH mass function: they preferentially occur in the smallest nucleated galaxies, they are visible to cosmological distances, and their light curves are governed by just a handful of free parameters. Furthermore, upcoming advances in time domain astronomy will turn TDE discovery from an artisanal into an industrial process: while less than 100 TDEs are known today, the upcoming LSST optical survey and ULTRASAT UV survey will each find thousands per year. In this talk, I will discuss the potential of TDEs to resolve long-standing questions on MBH demographics, origins, and evolution, focusing both on what can already be done today with techniques such as X-ray continuum fitting, and on the theoretical challenges that must be resolved before making further progress in optical/UV modeling. With an emphasis on recent progress in ab initio simulations, I will review the key theoretical questions concerning TDE flares: how does the debris circularize into an accretion flow? And what is the power source and geometry of the optical/UV emission? I will argue that the answer to these long-standing questions are finally emerging, and that observed optical/UV light curves can now be modeled from first principles.

Видео Tidal Disruption Events: A New Black Hole Census канала CfA Colloquium