The stream-stream collision after the tidal disruption of a star around a massive black hole

被引:42
作者
Kim, SS [1 ]
Park, MG
Lee, HM
机构
[1] Korea Adv Inst Sci & Technol, Dept Phys, Daejon 305701, South Korea
[2] Kyungpook Natl Univ, Dept Astron & Atmospher Sci, Taegu 702701, South Korea
[3] Pusan Natl Univ, Dept Earth Sci, Pusan 609735, South Korea
关键词
black hole physics; galaxies : nuclei; hydrodynamics; methods : numerical; radiation mechanisms : thermal;
D O I
10.1086/307394
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
A star can be tidally disrupted around a massive black hole. It is known that the debris forms a precessing stream, which may collide with itself. The stream collision is a key process in determining the subsequent evolution of the stellar debris: if the orbital energy is efficiently dissipated, the debris will eventually form a circular disk (or torus). In this paper, we have numerically studied such a stream collision resulting from the encounter between a 10(6) M. black hole and a 1 M. normal star with a pericenter radius of 100 R.. A simple treatment for radiative cooling has been adopted for both optically thick and optically thin regions. We have found that approximately 10% to 15% of the initial kinetic energy of the streams is converted into thermal energy during the collision. The spread in angular momentum of the incoming stream is increased by a factor of 2 to 3, and such an increase, together with the decrease in kinetic energy, significantly helps the circularization process. The initial luminosity burst produced by the collision may reach as high as 10(41) ergs s(-1) in 10(4) s, after which the luminosity increases again (but slowly this time) to a steady value of a few 10(40) ergs s(-1) in a few times 10(5) s. The radiation from the system is expected to be close to Planckian, with an effective temperature of similar to 10(5) K.
引用
收藏
页码:647 / 657
页数:11
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