Stellar tidal disruption events in general relativity

Stone, Nicholas C.; Kesden, Michael; Cheng, Roseanne M.; Velzen, S. van

doi:10.1007/s10714-019-2510-9

Cited by 89 publications

(85 citation statements)

References 237 publications

(331 reference statements)

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“…The most relativistic encounter shown in this work is a β = 3 disruption of a ZAMS Sun; here r p 14GM BH /c 2 . In this regime, relativistic effects on the rate of return of the fallback material are minor (Tejeda et al 2017;Stone et al 2019). Note also that in our simulations the tidal radius is 100R , meaning that the BH enters the computational domain as it moves through pericenter.…”

Section: Methodsmentioning

confidence: 99%

The Tidal Disruption of Sun-like Stars by Massive Black Holes

Law-Smith

Guillochon

Ramírez-Ruiz

2019

ApJL

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We present the first simulations of the tidal disruption of stars with realistic structures and compositions by massive black holes (BHs). We build stars in the stellar evolution code MESA and simulate their disruption in the 3D adaptive-mesh hydrodynamics code FLASH, using an extended Helmholtz equation of state and tracking 49 elements. We study the disruption of a 1M star and 3M star at zero-age main sequence (ZAMS), middle-age, and terminal-age main sequence (TAMS). The maximum BH mass for tidal disruption increases by a factor of ∼2 from stellar radius changes due to MS evolution; this is equivalent to varying BH spin from 0 to 0.75. The shape of the mass fallback rate curves is different from the results for polytropes of Guillochon & Ramirez-Ruiz (2013). The peak timescale t peak increases with stellar age, while the peak fallback rateṀ peak decreases with age, and these effects diminish with increasing impact parameter β. For a β = 1 disruption of a 1M star by a 10 6 M BH, from ZAMS to TAMS, t peak increases from 30 to 54 days, whileṀ peak decreases from 0.66 to 0.14 M /yr. Compositional anomalies in nitrogen, helium, and carbon can occur before the peak timescale for disruptions of MS stars, which is in contrast to predictions from the "frozen-in" model. More massive stars can show stronger anomalies at earlier times, meaning that compositional constraints can be key in determining the mass of the disrupted star. The abundance anomalies predicted by these simulations provide a natural explanation for the spectral features and varying line strengths observed in tidal disruption events.

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Section: Methodsmentioning

confidence: 99%

The Tidal Disruption of Sun-like Stars by Massive Black Holes

Law-Smith

Guillochon

Ramírez-Ruiz

2019

ApJL

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“…The x = ±1, a = 1 polynomial was previously given in factorized form in Eq. (24). The roots are all real, and they are (ordered by value)…”

Section: Number Of Real Equatorial Roots and Bracketsmentioning

confidence: 99%

“…Parabolic encounters are astrophysically interesting for modeling tidal disruptions of ordinary stars around supermassive black holes [23][24][25]. They are also interesting as potential sources of gravitational wave bursts [26,27].…”

Section: E Parabolic Trajectoriesmentioning

confidence: 99%

Location of the last stable orbit in Kerr spacetime

Stein

Warburton

2020

Phys. Rev. D

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Black hole spacetimes, like the Kerr spacetime, admit both stable and plunging orbits, separated in parameter space by the separatrix. Determining the location of the separatrix is of fundamental interest in understanding black holes, and is of crucial importance for modeling extreme mass-ratio inspirals. Previous numerical approaches to locating the Kerr separatrix were not always efficient or stable across all of parameter space. In this paper we show that the Kerr separatrix is the zero set of a single polynomial in parameter space. This gives two main results. First, we thoroughly analyze special cases (extreme Kerr, polar orbits, etc.), finding strict bounds on the limits of roots, and unifying a number of results in the literature. Second, we pose a stable numerical method which is guaranteed to quickly and robustly converge to the separatrix. This new approach is implemented in the Black Hole Perturbation Toolkit, and results in a ∼ 45× speedup over the prior robust approach. II. TIME-LIKE GEODESICS IN KERR SPACETIMEGiven any spacetime, let us denote the trajectory of a timelike (non-spinning) test body of mass µ by a curve x α (τ ) where τ is the proper time as measured along the world line. The four-velocity of the body is given by arXiv:1912.07609v1 [gr-qc]

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“…The fits are given in terms of functions of the penetration factor β (the first four being analogous to the A 5/3 , B 5/3 , C 5/3 and D 5/3 given by GRR13), and follow the scaling with the BH size M, the stellar mass m and radius r , the radiative efficiency and the canonical energy spread ∆E ref (Eq. 1 with k E = 1 and n = 0) given by GRR13 and Stone et al (2019):…”

Section: Appendix A: Fitting Parametersmentioning

confidence: 99%

“…The importance of general relativistic effects has recently been reviewed by Stone et al (2019), whereas results from simulations are summarized by Lodato et al (2015) and recent observational advances on TDEs can be found in Komossa (2015). 2,3,4,5,6,7,8,9,10, 11} BH spin a {−0.99, −0.5, 0, 0.5, 0.99} SPH particles N part 200 642 2 METHOD…”

Section: Introductionmentioning

confidence: 99%

Tidal disruptions by rotating black holes: effects of spin and impact parameter

Gafton

Rosswog

2019

Monthly Notices of the Royal Astronomical Society

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We present the results of relativistic smoothed particle hydrodynamics simulations of tidal disruptions of stars by rotating supermassive black holes, for a wide range of impact parameters and black hole spins. For deep encounters, we find that: relativistic precession creates debris geometries impossible to obtain with the Newtonian equations; part of the fluid can be launched on plunging orbits, reducing the fallback rate and the mass of the resulting accretion disc; multiple squeezings and bounces at periapsis may generate distinctive X-ray signatures resulting from the associated shock breakout; disruptions can occur inside the marginally bound radius, if the angular momentum spread launches part of the debris on non-plunging orbits. Perhaps surprisingly, we also find relativistic effects important in partial disruptions, where the balance between self-gravity and tidal forces is so precarious that otherwise minor relativistic effects can have decisive consequences on the stellar fate. In between, where the star is fully disrupted but relativistic effects are mild, the difference resides in a gentler rise of the fallback rate, a later and smaller peak, and longer return times. However, relativistic precession always causes thicker debris streams, both in the bound part (speeding up circularization) and in the unbound part (accelerating and enhancing the production of separate transients). We discuss various properties of the disruption (compression at periapsis, shape and spread of the energy distribution) and potential observables (peak fallback rate, times of rise and decay, duration of super-Eddington fallback) as a function of the impact parameter and the black hole spin.

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Stellar tidal disruption events in general relativity

Cited by 89 publications

References 237 publications

The Tidal Disruption of Sun-like Stars by Massive Black Holes

The Tidal Disruption of Sun-like Stars by Massive Black Holes

Location of the last stable orbit in Kerr spacetime

Tidal disruptions by rotating black holes: effects of spin and impact parameter

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