Delayed Stream Crossing for TDEs by Spinning Black Holes

When a star is tidally disrupted by a supermassive black hole (BH), the debris gas forms a thin cold stream whose longitudinal motion accurately follows the Kerr geodesics. If the BH is rapidly spinning, the stream often undergoes multiple pericenter passages before the self-crossing, as a result of strong Lense-Thirring precession (combined with apsidal precession). Using numerical and analytic models, we show that the delay time between the stellar disruption and self-crossing spans a wide range from months to a decade. Observational consequences of delayed mass feeding to the accretion flow will be discussed.