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Elliptical accretion disk as a model for tidal disruption events
  

Shanghai Astronomical Observatory Astrophysics Colloquium

TitleElliptical accretion disk as a model for tidal disruption events

SpeakerFukun Liu  (PKU)

Special Time10:00am Oct. 19th (Thursday)

Tencent Meeting576-157-8290 password: 6360

Location: Lecture Hall, 3rd floor

Report in Chinese

Abstract

A star would be tidally disrupted, when it closelypasses by a supermassive black hole (SMBH). After the tidal disruption, abouthalf of the stellar debris becomes bound and falls back to the SMBH. In the popularRees’ model for tidal disruption events (TDEs), the fallback stellar debris rapidlycircularizes to form a circular compact accretion disk, assuming that theself-crossing shocks of the streams is strong and near the orbital pericenterof the star because of the strong relativistic apsidal precession and the angularmomentum is conserved at the self-crossing shocks. However, the predictions of thepopular circular accretion disk model are seriously in tension with theobservations of TDEs, requiring important modifications to the simple model.Motiving by the results of recent numerical hydrodynamic simulations that the self-crossingshocks of streams can efficiently redistribute the angular momentum among theshocked material and the self-crossing shocks would lead to rapid accretion of matterinstead of rapid circularization, we recently proposed an elliptical accretiondisk model for TDEs. We showed that the elliptical accretion disks havedistinctive hydrodynamic structures and thermal spectral energy distributions,which are fully consistent with the observations of both optical/UV- and X-ray-discoveredTDEs. In this talk, I will give a brief introduction of the ellipticalaccretion disk model for TDEs.

CV

刘富坤,北京大学物理学院天文系教授,国务院特殊津贴专家,物理学院学术委员会委员,天文系前系主任,中国天文学会监事长。是国家自然科学奖、教育部自然科学奖评审专家,以色利国家自然科学基金国际评审专家,瑞典皇家科学院克拉福德(Crafoord)数学和天文奖(诺贝尔奖获得者F. Hoyle, R. Zenzel, A. Ghez, J. Peebles以及著名天文学家A. Sandage, L. Spitzer Jr, F.Hoyle, E. Salpeter, J. Gunn, M. Rees, E. Parker, R. Blandford, R. Kerr, R.Sunyaev等以及菲尔兹奖获得者E. Bombieri, J. Bourgain, A. Connes, S. Donaldson, A. Grothendieck, M.Kontsevich, S.-T. Yau(丘成桐)T. Tao(陶哲轩), E. Witten曾获此奖)、科维理(Kavli)(诺贝尔奖获得者基普.索恩、雷纳.韦斯等曾获此奖)提名专家。

 

1999年获意大利国际高等研究生院博士,1999年至2001年在哥德堡大学和查尔姆斯技术大学做瑞典国家自然科学基金博士后(NFR Fellow)2001年回国进入北京大学物理学院天文系工作至今。长期从事黑洞、吸积盘、活动星系核及高能和引力天体物理的研究。发现了活动星系核中引力波辐射主导阶段超大质量双黑洞-吸积盘共同演化系统脱离耦,快速并合的超大质量双黑洞剪除吸积盘内区而导致活动星系核活动暂停现象 (2003);发现了超大质量双黑洞的散射作用会极大增强恒星潮汐撕裂事件率(2009);预言了单个恒星潮汐撕裂事件中超大质量双黑洞的扰动将导致吸积短暂中断的现象(2009);根据该理论对潮汐撕裂事件光变的理论预言发现了正常星系中的超大质量双黑洞(2014),被国际同行誉为属于改变我们宇宙观、开启全新天文研究新领域的发现;提出了全新的黑洞椭圆吸积盘理论模型(20017年、2021)。研究成果先后入选2011年度和2014年度“中国天文十大科技进展”。2016年获国务院特殊津贴。

 

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