Classification of Tidal Disruption Events Based on Stellar Orbital Properties

Hayasaki, Kimitake; Zhong, Shiyan; Li, Shuo; Berczik, Peter; Spurzem, Rainer

doi:10.3847/1538-4357/aab0a5

Cited by 33 publications

(53 citation statements)

References 53 publications

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“…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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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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“…This will occur if the relative velocity v∞ between the star and the compact object is too large for any of the tidal debris to remain bound, i.e. if v 2 ∞ /2 > (mc/m ) 1/3 Gm /r (Hayasaki et al 2018). We have excluded such hyperbolic micro-TDEs from our rate estimates.…”

Section: Tidal Disruptions By Stellar Mass Compact Objectsmentioning

confidence: 99%

An overabundance of black hole X-ray binaries in the Galactic Centre from tidal captures

Generozov

Stone

Metzger

et al. 2018

Monthly Notices of the Royal Astronomical Society

106

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A large population of X-ray binaries (XRBs) was recently discovered within the central parsec of the Galaxy by Hailey et al. While the presence of compact objects on this scale due to radial mass segregation is, in itself, unsurprising, the fraction of binaries would naively be expected to be small because of how easily primordial binaries are dissociated in the dynamically hot environment of the nuclear star cluster (NSC). We propose that the formation of XRBs in the central parsec is dominated by the tidal capture of stars by black holes (BHs) and neutron stars (NSs). We model the time-dependent radial density profiles of stars and compact objects in the NSC with a Fokker-Planck approach, using the present-day stellar population and rate of in situ massive star (and thus compact object) formation as observational constraints. Of the ∼ 1 − 4 × 10 4 BHs that accumulate in the central parsec over the age of the Galaxy, we predict that ∼ 60 − 200 currently exist as BH-XRBs formed from tidal capture, consistent with the population seen by Hailey et al. A somewhat lower number of tidal capture NS-XRBs is also predicted. We also use our observationally calibrated models for the NSC to predict rates of other exotic dynamical processes, such as the tidal disruption of stars by the central supermassive black hole (∼ 10 −4 per year at z=0).

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“…Most of observations on tidal disruption right now, however, have assumed that disrupted stars are in parabolic orbits. In reality, the light curve of a TDE from eccentric or hyperbolic star can be significantly different from the "classic" parabolic orbits (Hayasaki et al 2013(Hayasaki et al , 2018. As extreme cases, all the debris from disrupted stars with strongly bound eccentric orbits will fall back to the SMBH, leading to a significant deviation from the "canonical" t −5/3 fall back rate.…”

Section: Observation Implicationsmentioning

confidence: 99%

Direct N-body Simulations of Tidal Disruption Rate Evolution in Unequal-mass Galaxy Mergers

Berczik

Xian

et al. 2019

ApJ

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The hierarchical galaxy formation model predicts supermassive black hole binaries (SMBHBs) in galactic nuclei. Due to the gas poor environment and the limited spatial resolution in observations they may hide in the center of many a galaxy. However, a close encounter of a star with one of the supermassive black holes (SMBHs) may tidally disrupt it to produce a tidal disruption event (TDE) and temporarily light up the SMBH. In a previous work, we investigated with direct N-body simulations the evolution of TDE rates of SMBHB systems in galaxy mergers of equal mass. In this work we extend to unequal mass mergers. Our results show that, when two SMBHs are far away from each other, the TDE rate of each host galaxy is similar as in an isolated galaxy. As the two galaxies and their SMBHs separation shrinks, the TDE rate is increasing gradually until it reaches a maximum shortly after the two SMBHs become bound. In this stage, the averaged TDE rate can be enhanced by several times to an order of magnitude relative to isolated single galaxies. Our simulations show that the dependence of the TDE accretion rate on the mass ratio in this stage can be well fitted by power law relations for both SMBHs. After the bound SMBHB forms, the TDE rate decreases with its further evolution. We also find that in minor mergers TDEs of the secondary SMBH during and after the bound binary formation are mainly contributed by stars from the other galaxy.Corresponding author: Shuo Li lishuo@nao.cas.cn 2 Li et al.

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Classification of Tidal Disruption Events Based on Stellar Orbital Properties

Cited by 33 publications

References 53 publications

Location of the last stable orbit in Kerr spacetime

Location of the last stable orbit in Kerr spacetime

An overabundance of black hole X-ray binaries in the Galactic Centre from tidal captures

Direct N-body Simulations of Tidal Disruption Rate Evolution in Unequal-mass Galaxy Mergers

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