The History of Tidal Disruption Events in Galactic Nuclei

Danor Aharon, Alessandra Mastrobuono Battisti, Hagai B. Perets

Published 2015-07-29Version 1

The tidal disruption of a star by a massive black hole (MBH) is thought to produce a transient luminous event. Such tidal disruption events (TDEs) may play an important role in detecting and characterizing MBHs and probe the properties and dynamics of their nuclear stellar clusters (NSCs) hosts. Previous studies estimated the recent rates of TDEs in the local universe. However, the long-term evolution of the TDEs rate throughout the history of the universe have been hardly explored. Here we consider the TDEs history, using simple evolutionary models for the formation and evolution of galactic nuclei. We use a 1D Fokker-Planck approach to explore the evolution of MBH-hosting NSCs, and obtain the disruption rates of stars during their evolution. We complement these with an analysis of TDEs history based on N-body simulation data, and find them to be comparable. We consider NSCs that are built-up from close-in star formation or from star formation/clusters-dispersal far-out, a few pc from the MBH. We also explore cases where primordial NSCs exist and later further evolve through such additional star-formation/cluster-dispersal processes. We study the dependence of the TDE history on the type of galaxy (in terms of its star-formation history), as well as the dependence on the MBH mass. These provide several scenarios for the TDEs history, with a continuous increase of the TDE rates over time for cases of far-out star-formation and a more complex behavior for the close-in star formation cases. The total highest rates are found for the lowest mass MBHs, the highest star-formation rates and in elliptical galaxies, where the galaxy and NSC are assumed to have formed at early stages. Finally, we integrate the TDE histories of the various type of galaxies and MBHs to provide a total TDE history of the universe, which can be potentially probed with future large surveys (e.g. LSST).