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Tidal disruption events of stars by intermediate-mass black holes

Presentation #116.05 in the session Stellar/Compact Objects.

Published onJul 01, 2023
Tidal disruption events of stars by intermediate-mass black holes

IMBHs may form in dense star clusters via the merger of stellar-mass black holes or the collapse of very massive stars. Within these dense environments, tidal disruption events (TDEs) of cluster stars are likely to produce electromagnetic signatures for detecting IMBHs with a long-lived super-Eddington accretion phase. Depending upon the distance at the closest approach, these events can lead to a fully disrupted star or partially disrupted bound/unbound remnant. In this work, we perform a wide range of hydrodynamic simulations of close encounters between a main-sequence star and massive black holes using the SPH code StarSmasher. We find that the 1M middle-age main-sequence star is partially disrupted with a surviving core after the first passage for pericenter distances greater than 0.3rT, where rT is the classical tidal disruption radius of the star. In general, higher black hole masses and higher penetration factors lead to more mass loss at the pericenter passage and hence tend to kick the star out while full disruption is the final outcome only for star to black hole mass ratios relatively close to unity. In the case of lower penetrating factors, the star is bound to the black hole and undergoes multiple pericenter passages with the number of passages before ejection tends to decrease as the black hole mass is increased. In the MBH=10M case, the repeated passages end up leading to full disruption while in the cases with MBH≥100 M, the percentage of mass stripped from the star increases with each pericenter passage, eventually leading to an ejection. In principle, observations of consecutive electromagnetic flares from these repeated passages could help to constrain the black hole mass of the event from the number of flares observed.

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