Orbital Decay and Tidal Disruption of a Star Cluster: Analytical Calculation

2003 ◽  
Vol 585 (1) ◽  
pp. 250-255 ◽  
Author(s):  
Hideaki Mouri ◽  
Yoshiaki Taniguchi
Keyword(s):  
Analytical Calculation ◽  
Star Cluster ◽  
Tidal Disruption ◽  
Orbital Decay

scholarly journals The evolution of kicked stellar-mass black holes in star cluster environments - II. Rotating star clusters

2019 ◽  
Vol 488 (3) ◽  
pp. 3055-3066
Author(s):  
Jeremy J Webb ◽  
Nathan W C Leigh ◽  
Roberto Serrano ◽  
Jillian Bellovary ◽  
K E Saavik Ford ◽  
...  
Keyword(s):  
Black Holes ◽  
Time Scale ◽  
Rotation Axis ◽  
Star Cluster ◽  
High Mass ◽  
Capture Event ◽  
Orbital Decay ◽  
Orbital Frequency ◽  
Decay Times ◽  
Rotating Star

Abstract In this paper, we continue our study on the evolution of black holes (BHs) that receive velocity kicks at the origin of their host star cluster potential. We now focus on BHs in rotating clusters that receive a range of kick velocities in different directions with respect to the rotation axis. We perform N-body simulations to calculate the trajectories of the kicked BHs and develop an analytic framework to study their motion as a function of the host cluster and the kick itself. Our simulations indicate that for a BH that is kicked outside of the cluster’s core, as its orbit decays in a rotating cluster the BH will quickly gain angular momentum as it interacts with stars with high rotational frequencies. Once the BH decays to the point where its orbital frequency equals that of local stars, its orbit will be circular and dynamical friction becomes ineffective since local stars will have low relative velocities. After circularization, the BH’s orbit decays on a longer time-scale than if the host cluster was not rotating. Hence BHs in rotating clusters will have longer orbital decay times. The time-scale for orbit circularization depends strongly on the cluster’s rotation rate and the initial kick velocity, with kicked BHs in slowly rotating clusters being able to decay into the core before circularization occurs. The implication of the circularization phase is that the probability of a BH undergoing a tidal capture event increases, possibly aiding in the formation of binaries and high-mass BHs.

scholarly journals Enhancement of the tidal disruption event rate in galaxies with a nuclear star cluster: from dwarfs to ellipticals

2020 ◽  
Vol 497 (2) ◽  
pp. 2276-2285 ◽  
Author(s):  
Hugo Pfister ◽  
Marta Volonteri ◽  
Jane Lixin Dai ◽  
Monica Colpi
Keyword(s):  
Black Holes ◽  
Milky Way ◽  
Event Rate ◽  
Star Cluster ◽  
Scaling Relations ◽  
Tidal Disruption ◽  
Massive Black Holes ◽  
First Time ◽  
Stellar Density ◽  
Disruption Event

ABSTRACT We compute the tidal disruption event (TDE) rate around local massive black holes (MBHs) with masses as low as $2.5\times 10^4\, \mathrm{M}_{\odot }$, thus probing the dwarf regime for the first time. We select a sample of 37 galaxies for which we have the surface stellar density profile, a dynamical estimate of the mass of the MBH, and 6 of which, including our Milky Way, have a resolved nuclear star cluster (NSC). For the Milky Way, we find a total TDE rate of ${\sim}10^{-4}\, \mathrm{yr}^{-1}$ when taking the NSC in account, and ${\sim}10^{-7} \, \mathrm{yr}^{-1}$ otherwise. TDEs are mainly sourced from the NSC for light (${\lt}3\times 10^{10}\, \mathrm{M}_{\odot }$) galaxies, with a rate of few $10^{-5}\, \mathrm{yr}^{-1}$, and an enhancement of up to two orders of magnitude compared to non-nucleated galaxies. We create a mock population of galaxies using different sets of scaling relations to explore trends with galaxy mass, taking into account the nucleated fraction of galaxies. Overall, we find a rate of few $10^{-5}\, \mathrm{yr}^{-1}$ which drops when galaxies are more massive than $10^{11}\, \mathrm{M}_{\odot }$ and contain MBHs swallowing stars whole and resulting in no observable TDE.

On the likelihood of Gravitational Wave emission during the Tidal Disruption of stars by Super Massive Black Holes

2018 ◽  
Vol 14 (S342) ◽  
pp. 275-277
Author(s):  
Martina Toscani ◽  
Giuseppe Lodato
Keyword(s):  
Analytical Calculation ◽  
High Energy ◽  
X Rays ◽  
Tidal Disruption ◽  
Massive Black Holes ◽  
Laser Interferometer Space Antenna ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Mass Quadrupole ◽  
High Energy Emission

AbstractTidal Disruption Events (TDEs) are a common feature between Active and Quiescent Galactic Nuclei; the study of these events is a very useful tool to probe phenomena that relate to the formation of an accretion disc or a jet. Also, the accretion rate at the beginning of the tidal flare is expected to be significantly super-Eddington and might result in high energy emission (in soft X-rays but sometimes up to the gamma regime, as in the the case of Swift J1644, see Komossa 2015). These events may even play an important role in the newborn field of the Multimessenger Astronomy. This work is set within this context. Indeed, it is a study of generation of Gravitational Waves (GWs) from the hot accreting torus resulting after a TDE. Since the torus has only formed recently, magnetic fields are not expected to be strong enough, so that the torus is likely to be unstable to the Papaloizou-Pringle Instability (PPI), producing a strongly varying mass quadrupole. Here, the study of the evolution of such tori is developed, using both analytical calculation and a Smoothed Particle Hydrodynamics simulation (SPH). In particular the goal of this work is to determine the GW waveform and to compute the characteristic strain of these GWs in order to see if they are detectable by the Laser Interferometer Space Antenna (LISA).

scholarly journals Mass ratio, the hills mechanism, and the galactic centre S-stars

2020 ◽  
Author(s):  
Aleksey Generozov
Keyword(s):  
Star Cluster ◽  
Galactic Centre ◽  
Centre Of Mass ◽  
Mass Ratio ◽  
Tidal Disruption ◽  
Primary Star ◽  
B Stars ◽  
Apparent Inconsistency ◽  
Order Of Magnitude ◽  
Central Parsec

Abstract The Galactic centre contains several young populations within its central parsec: a disk between ∼0.05 to 0.5 pc from the centre, and the isotropic S-star cluster extending an order of magnitude further inwards in radius. Recent observations (i.e. spectroscopy and hypervelocity stars) suggest that some S-stars originate in the disk. In particular, the S-stars may be remnants of tidally disrupted disk binaries. However, there is an apparent inconsistency in this scenario: the disk contains massive O and Wolf–Rayet stars while the S-stars are lower mass, B stars. We explore two different explanations for this apparent discrepancy: (i) a built-in bias in binary disruptions, where the primary star remains closer in energy to the centre-of-mass orbit than the secondary and (ii) selective tidal disruption of massive stars within the S-star cluster. The first explanation is plausible. On the other hand, tidal disruptions have not strongly affected the mass distribution of the S-stars over the last several Myr.

Growth of intermediate mass black holes in first star clusters

2019 ◽  
Vol 14 (S351) ◽  
pp. 220-223
Author(s):  
Yuya Sakurai ◽  
Naoki Yoshida ◽  
Michiko S. Fujii
Keyword(s):  
Black Holes ◽  
Large Scale ◽  
Star Clusters ◽  
Star Cluster ◽  
Galaxy Mergers ◽  
Intermediate Mass ◽  
Tidal Disruption ◽  
Stellar Collisions ◽  
Gas Supply ◽  
Intermediate Mass Black Holes

AbstractWe study runaway stellar collisions in primordial star clusters and formation of intermediate mass black holes (IMBHs). Using cosmological simulations, we identify eight atomic-cooling halos in which the star clusters form. We follow stellar and dark matter (DM) dynamics for 3Myr using hybrid N-body simulations. We find that the runaway stellar collisions occur in all star clusters and IMBHs with masses ∼400–1900M⊙ form. Performing additional N-body simulations, we explore evolutions of the IMBHs in the star clusters for 15 Myr. The IMBH masses grow via stellar tidal disruption events (TDEs) to ∼700–2500 M⊙. The TDE rates are ∼0.3–1.3 Myr−1. DM motions affect the star cluster evolutions and reduce the TDE rates. The IMBHs may subsequently grow to SMBHs by gas supply through galaxy mergers or large-scale gas inflows, or they may remain within or around the clusters.

Monte Carlo Modelling of Secondary Electron Yield from Rough Surfaces

1990 ◽  
Vol 48 (1) ◽  
pp. 422-423
Author(s):  
John C. Russ
Keyword(s):  
Monte Carlo ◽  
Energy Loss ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Analytical Calculation ◽  
Mean Free Path ◽  
Single Scattering ◽  
High Energy ◽  
Secondary Electron Yield ◽  
Electron Yield

Monte-Carlo programs are well recognized for their ability to model electron beam interactions with samples, and to incorporate boundary conditions such as compositional or surface variations which are difficult to handle analytically. This success has been especially powerful for modelling X-ray emission and the backscattering of high energy electrons. Secondary electron emission has proven to be somewhat more difficult, since the diffusion of the generated secondaries to the surface is strongly geometry dependent, and requires analytical calculations as well as material parameters. Modelling of secondary electron yield within a Monte-Carlo framework has been done using multiple scattering programs, but is not readily adapted to the moderately complex geometries associated with samples such as microelectronic devices, etc.This paper reports results using a different approach in which simplifying assumptions are made to permit direct and easy estimation of the secondary electron signal from samples of arbitrary complexity. The single-scattering program which performs the basic Monte-Carlo simulation (and is also used for backscattered electron and EBIC simulation) allows multiple regions to be defined within the sample, each with boundaries formed by a polygon of any number of sides. Each region may be given any elemental composition in atomic percent. In addition to the regions comprising the primary structure of the sample, a series of thin regions are defined along the surface(s) in which the total energy loss of the primary electrons is summed. This energy loss is assumed to be proportional to the generated secondary electron signal which would be emitted from the sample. The only adjustable variable is the thickness of the region, which plays the same role as the mean free path of the secondary electrons in an analytical calculation. This is treated as an empirical factor, similar in many respects to the λ and ε parameters in the Joy model.

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