Simulations of Tidal Disruption Events
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Simulations of Tidal Disruption Events Giuseppe Lodato1 · Roseanne M. Cheng2 · Clément Bonnerot3 · Jane Lixin Dai4
Received: 23 May 2019 / Accepted: 17 May 2020 © Springer Nature B.V. 2020
Abstract Numerical simulations have historically played a major role in understanding the hydrodynamics of the tidal disruption process. Given the complexity of the geometry of the system, the challenges posed by the problem have indeed stimulated much work on the numerical side. Smoothed Particles Hydrodynamics methods, for example, have seen their very first applications in the context of tidal disruption and still play a major role to this day. Likewise, initial attempts at simulating the evolution of the disrupted star with the so-called affine method have been historically very useful. In this Chapter, we provide an overview of the numerical techniques used in the field and of their limitations, and summarize the work that has been done to simulate numerically the tidal disruption process. Keywords Black hole physics · Galaxies: nuclei · Hydrodynamics · Methods: numerical
The Tidal Disruption of Stars by Massive Black Holes Edited by Peter G. Jonker, Sterl Phinney, Elena Maria Rossi, Sjoert van Velzen, Iair Arcavi and Maurizio Falanga
B G. Lodato
[email protected] R.M. Cheng [email protected] C. Bonnerot [email protected] J.L. Dai [email protected]
1
Dpartimento di Fisica, Università degli Studi di Milano, Via Celoria 16, Milano, Italy
2
Theoretical Division (T-1, T-3), Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545, USA
3
TAPIR, California Institute of Technology, Mailcode 350-17, Pasadena, CA 91125, USA
4
Department of Physics, The University of Hong Kong, Pok-fulam Road, Hong Kong, Hong Kong
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1 Introduction The dynamics of tidal disruption events is relatively complex. It involves treating the hydrodynamics of a self-gravitating fluid (the star), subject to a general relativistic force provided by the black hole. A full treatment of the problem would thus involve a general relativistic (magneto)-hydrodynamics code including heating and radiation. In some respects, this is what is also required when describing accretion flows around black holes in other systems, such as Active Galactic Nuclei, X-ray Binaries, and Ultra Luminous X-ray sources. Here the situation is made more complex because of the rapid variability of the system and the process of disruption, which is composed of several stages that are best described separately. In a nutshell, we can describe a TDE as being composed of three separate phases: (a) the disruption phase, (b) the evolution of the disrupted stream leading to disc formation, and (c) the accretion phase. In the disruption phase, the relevant physics is essentially the stellar self-gravity, fluid dynamics, and the tidal field of the black hole. For highly penetrating events, the tidal compression can lead to nuclear detonation (at least in the case of the disruption of a white dwarf), introducing complex thermodynam
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