Probing black hole mass, spin and general relativistic effects in tidal disruption flares----中国科学院紫金山天文台

Seminar Title	Probing black hole mass, spin and general relativistic effects in tidal disruption flares

Speaker:	Prof. YU Wenfei

Affiliation:	(Shanghai Astronomical Observatory)

When	Tuesday morning, Aug 20, 10:30 a.m.

Where:	Room 302 No.3 building , Xianlin campus (PMO, CAS)
	Welcome to Attend

	( PMO Academic Committee & Academic Circulating committee)

Abstract: When normal stars run close enough to previously dormant supermassive black holes (SMBHs) at the centers of normal galaxies, they would be entirely or partly disrupted due to the tidal force of the central SMBH, leading to the so-called tidal disruption events (TDEs). Part of the debris of the disrupted stars will be accreted by the SMBHs afterwards and generate accretion flares usually in the optical, UV band, and X-ray band. These flares provide great opportunities to probe those dormant SMBHs at the centers of normal galaxies, which represent the majority of SMBHs in our universe. Here we show predicted relativistic line features and the spectral line evolution expected to occur during the accretion phase of the debris material. These spectral line features are imprints of the mass and the spin of the previously dormant SMBHs while bring clues to the geometry and properties of the accretion flow, providing unique probes of the general relativistic Lense-Thirring precession and the Bardeen-Petterson effect expected in TDEs. In the next decade, sensitive wide field-of-view monitoring in the radio band with the SKA or the ngVLA will be able to detect jet activities due to the accretion of the debris flow of disrupted stars onto the SMBH at the very early stage when the mass accretion rate onto the SMBHs is very low, allowing us to probe mass and spin of those dormant SMBHs and detect general relativistic effects through follow-up X-ray observations.