Tidal Disruption Events by a Massive Black Hole Binary

TL;DR

This paper investigates how the presence of a massive black hole binary affects the debris dynamics and observable signatures of tidal disruption events, revealing distinctive features in light curves and accretion behavior.

Contribution

It introduces a detailed dynamical model of TDE debris in a binary black hole system, highlighting how the binary's potential modifies debris fallback and accretion patterns.

Findings

Gaps in light curves occur when debris misses the accretion radius.

Distinct 'continuous' and 'delayed' fallback components are identified.

Close encounters with the secondary black hole significantly influence fallback rates.

Abstract

Massive black hole binaries (MBHBs) are a natural byproduct of galaxy mergers. Previous studies have shown that flares from stellar tidal disruption events (TDEs) are modified by the presence of a secondary perturber, causing interruptions in the light curve. We study the dynamics of TDE debris in the presence of a milliparsec-separated MBHB by integrating ballistic particle orbits in the time-varying potential of the binary. We find that gaps in the light curve appear when material misses the accretion radius on its first return to pericentre. Subsequent recurrences can be decomposed into "continuous" and "delayed" components, which exhibit different behaviour. We find that this potential can substantially alter the locations of stream self-intersections. When debris is confined to the plane, we find that close encounters with the secondary BH leave noticeable signatures on the fallback rate and can result in significant accretion onto the secondary BH. Tight, equal-mass MBHBs accrete equally, periodically trading the infalling stream.