报告摘要

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 for us 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 of the accretion flow, providing unique probes of the general relativistic Lense-Thirring precession and the Bardeen-Petterson effect expected in TDEs.

Our on-going XMM/Swift joint observation program on future TDE flares is focused on these fundamental astrophysical problems. In the next decade, sensitive wide field-of-view monitoring in the radio band with the SKA or ngVLA will be able to detect tiny 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 is very low, while X-ray telescopes with a large area such as the eXTP will be able to detect these spectral line features. These allow us to probe mass and spin of those dormant SMBHs and detect general relativistic effects through follow-up X-ray observations of TDE flares.

报告人

Wenfei Yu (Shanghai Astronomical Observatory)

报告人介绍

余文飞，上海天文台研究员。1993年起，先后在高能物理研究所、美国NASA/MSFC/USRA、荷兰阿姆斯特丹大学以及美国伊利诺依大学香槟分校从事高能天文、空间观测和数据分析和相对论天体物理问题的研究工作。博士论文入选2000年“全国优秀博士论文”。曾经多次担任美国NASA天文卫星观测提案评审， 于2017-2018担任天文大科学中心FAST杰出学者。现为中欧合作eXTP卫星、中法合作SVOM卫星、以及国际平方公里阵列SKA等今后空间和地面大型天文观测设备相关科学工作组的重要成员。课题组主要从事对黑洞和中子星双星以及银河系内外暂现源的空间和地面多波段观测和有关相对论天体物理问题的研究，关注来自黑洞和中子星附近强引力场区域的短时标光变信号和长时标能谱演化等涉及致密天体性质和吸积物理的观测现象，已经发表了几十篇主要贡献的发现性论文。

地点

物理学院新楼5楼多功能厅

时间

4月3日上午10点-12点

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