GENERAL RELATIVISTIC HYDRODYNAMIC SIMULATION OF ACCRETION FLOW FROM A STELLAR TIDAL DISRUPTION

By H. Shiokawa, Julian Krolik, R. Cheng, T. Piran, Scott Noble. 2015

191 citations recorded by the source corpus.

We study how the matter dispersed when a supermassive black hole tidally disrupts a star joins an accretion flow. Combining a relativistic hydrodynamic simulation of the stellar disruption with a relativistic hydrodynamics simulation of the subsequent debris motion, we track the evolution of such a system until ≃ 80 % ?> of the stellar mass bound to the black hole has settled into an accretion flow. Shocks near the stellar pericenter and also near the apocenter of the most tightly bound debris dissipate orbital energy, but only enough to make its characteristic radius comparable to the semimajor axis of the most bound material, not the tidal radius as previously envisioned. The outer shocks are caused by post-Newtonian relativistic effects, both on the stellar orbit during its disruption and on the tidal forces. Accumulation of mass into the accretion flow is both non-monotonic and slow, requiring several to 10 times the orbital period of the most tightly bound tidal streams, while the inflow time for most of the mass may be comparable to or longer than the mass accumulation time. Deflection by shocks does, however, cause some mass to lose both angular momentum and energy, permitting it to move inward even before most of the mass is accumulated into the accretion flow. Although the accretion rate still rises sharply and then decays roughly as a power law, its maximum is ≃ 0.1 × ?> the previous expectation, and the timescale of the peak is ≃ 5 × ?> longer than previously predicted. The geometric mean of the black hole mass and stellar mass inferred from a measured event timescale is therefore ≃ 0.2 × ?> the value given by classical theory.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/7d00fc150a88b1f665bb79cdccc99427015e27b3

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Citations in the corpus

A Unified Model for Tidal Disruption Events (2018, unknown): “Hydrodynamical simulations (Shiokawa et al. 2015; Bonnerot et al. 2016; Hayasaki et al. 2016) and semi-analytical studies (Dai et al. 2013, 2015; Guillochon & Ramirez-Ruiz 2015) have shown that only in certain parameter regions can fast disk assembly happen.”
Revisiting Optical Tidal Disruption Events with iPTF16axa (2017, background): “Hydrodynamical simulations also suggest that stream-stream collisions may be responsible for the observed UV/optical emission of TDEs (Piran et al. 2015; Shiokawa et al. 2015; Bonnerot et al. 2017; Jiang et al. 2016).”
A bright year for tidal disruptions (2015, background): “…are collisions between the eccentric streams of stellar debris created during the disruption, which may contribute to the process of debris circularization (e.g., Hayasaki et al. 2013, Cheng & Bogdanović 2014, Hayasaki et al. 2015, Shiokawa et al. 2015, Piran et al. 2015, Bonnerot et al. 2015).”
ASASSN-15oi: a rapidly evolving, luminous tidal disruption event at 216 Mpc (2016, background): “…physical parameters, including the depth of the encounter, the composition of the star, the fraction of the star that is accreted, and the geometry of the accretion stream (e.g., Kochanek 1994; Lodato & Rossi 2011; Guillochon & Ramirez-Ruiz 2015; Metzger & Stone 2015; Shiokawa et al. 2015).”
Weighing Black Holes Using Tidal Disruption Events (2018, background): “In order for the luminosity to follow the fallback rate, the stellar debris that initially returns on highly eccentric orbits must circularize on a timescale that is shorter than the fallback timescale (Shiokawa et al. 2015; Bonnerot et al. 2016b; Hayasaki et al. 2016).”
Disc formation from tidal disruptions of stars on eccentric orbits by Schwarzschild black holes (2015, methodology): “These results are discussed in Section 4 and compared to other studies by Shiokawa et al. (2015) and Hayasaki, Stone & Loeb (2015) that appeared at the same time as this paper.”
Six months of multiwavelength follow-up of the tidal disruption candidate asassn-14li and implied tde rates from asas-sn (2015, background): “…flare will be proportional to the rate of return of the stellar material to pericenter, but the exact return rates depend on the complex physics associated with the evolution of the accretion stream (e.g., Kochanek 1994; Lodato & Rossi 2011; Guillochon & Ramirez-Ruiz 2015; Shiokawa et al. 2015).”
MOCCA code for star cluster simulations – IV. A new scenario for intermediate mass black hole formation in globular clusters (2015, background): “…radiation heating the gas, etc. - all of them not included in simulations presented in this paper) and recent simulations suggest that less than 50% of the incoming star mass can be directly accreted onto the BH (see e.g. Guillochon & Ramirez-Ruiz 2013; Kyutoku et al. 2015; Shiokawa et al. 2015).”
New Physical Insights about Tidal Disruption Events from a Comprehensive Observational Inventory at X-Ray Wavelengths (2016, background): “However, exactly how depends heavily on the evolution and physics within the accretion stream (e.g., Kochanek 1994; Ramirez-Ruiz & Rosswog 2009; Lodato & Rossi 2011; Guillochon & Ramirez-Ruiz 2013; Cheng & Bogdanović 2014; Guillochon & RamirezRuiz 2015; Shiokawa et al. 2015).”