Spiral shocks and accretion in discs

Spruit, H. C.; Matsuda, Takuya; Inoue, Minoru; Sawada, Keisuke

doi:10.1093/mnras/229.4.517

Cited by 106 publications

(88 citation statements)

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“…Previous Newtonian simulations (see, e.g. (Savonije et al 1994;Makita et al 2000;Ju et al 2016)), as well as analytic theory (Spruit et al 1987;Savonije et al 1994;Rafikov 2016), predict the dominant spiral shock mode should be m = 2. So, too, does the recent work of Ryan & MacFadyen (2016), in which mini-disk dynamics driven by the BH at the center of the disk were treated in full general relativity, but the tidal field due to a BH companion was added as a perturbation.…”

Section: Spiral Density Wavesmentioning

confidence: 90%

“…The circular orbit data of Paczynski (1977), for example, can be fit reasonably well by the expression r t = 0.27q ∓0.3 a where ∓ correspond to the primary and secondary BH respectively, and q ≤ 1 is the binary mass ratio (Roedig et al 2014). Other Newtonian work has shown that tidal torques from the companion can excite spiral waves that steepen into shocks (Lynden-Bell & Pringle 1974;Spruit et al 1987;Papaloizou & Lin 1995;Ju et al 2016;Rafikov 2016), supplementing the internal stresses due to correlated MHD turbulence. Similar conclusions were recently obtained in the context of a binary system where the mini-disks are placed around Schwarzschild BHs, but the binary separation is taken to be in the Newtonian regime (Ryan & MacFadyen 2016).…”

Section: Introductionmentioning

confidence: 99%

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Relativistic Dynamics and Mass Exchange in Binary Black Hole Mini-disks

Bowen

Campanelli

Krolik

et al. 2017

ApJ

113

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We present the first exploration of gas dynamics in a relativistic binary black hole system in which an accretion disk (a "mini-disk") orbits each black hole. We focus on 2D hydrodynamical studies of comparable-mass, non-spinning systems. Relativistic effects alter the dynamics of gas in this environment in several ways. Because the gravitational potential between the two black holes becomes shallower than in the Newtonian regime, the mini-disks stretch toward the L1 point and the amount of gas passing back and forth between the mini-disks increases sharply with decreasing binary separation. This "sloshing" is quasi-periodically modulated at 2 and 2.75 times the binary orbital frequency, corresponding to timescales of hours to days for supermassive binary black holes. In addition, relativistic effects add an m = 1 component to the tidally-driven spiral waves in the disks that are purely m = 2 in Newtonian gravity; this component becomes dominant when the separation is ∼ < 100 gravitational radii. Both the sloshing and the spiral waves have the potential to create distinctive radiation features that may uniquely mark supermassive binary black holes in the relativistic regime.

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Section: Spiral Density Wavesmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Relativistic Dynamics and Mass Exchange in Binary Black Hole Mini-disks

Bowen

Campanelli

Krolik

et al. 2017

ApJ

113

View full text Add to dashboard Cite

show abstract

“…In some astrophysical situations, numerical simulations (e.g. Hernquist & Katz 1989;Nelson & Papaloizou 1994;Katz et al 1996;Bate & Burkert 1997;Spruit et al 1987; show a high particle concentration with 30 to 50 particle neighbours or more. According to the neighbours histograms shown in Fig.…”

Section: Sph Accuracymentioning

confidence: 99%

“…Chakrabarti (1992), Bisikalo et al (1999), spiral patterns do not appear if a polytropic index (appearing in the perfect gas state equation) γ > 1.16 is adopted. According to some others, such as Sawada et al (1987), Spruit et al (1987), Kaisig (1989), Matsuda et al (1990Matsuda et al ( , 1992, Ichikawa & Osaki (1992, 1994, Sawada & Matsuda (1992), Savonije et al (1994), Yukawa et al (1997), Makita et al (2000), spiral patterns and radial shocks always exist whatever the γ is and the initial kinematic conditions are. Tidal effects should be responsible for spirals and spiral shock development in the disc bulk, starting from the outer disc edge.…”

Section: Introductionmentioning

confidence: 98%

Low compressibility accretion disc formation in close binaries: the role of physical viscosity

Lanzafame

Belvedère

Molteni

2006

A&A

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Aims. Physical viscosity naturally hampers gas dynamics (rarefaction or compression). Such a role should support accretion disc development inside the primary gravitation potential well in a close binary system, even for low compressibility modelling. Therefore, from the astrophysical point of view, highly viscous accretion discs could exist even in the low compressibility regime showing strong thermal differences to high compressibility ones Methods. We performed simulations of stationary Smooth Particle Hydrodynamics (SPH) low compressibility accretion disc models for the same close binary system. Artificial viscosity operates in all models. The absence of physical viscosity and a supersonic high mass transfer characterize the first model. Physical viscosity and the same supersonic high mass transfer characterize the second model, whilst physical viscosity and a subsonic low mass transfer characterize the third model. The same binary system parameters, such as stellar masses and their separation, have been adopted, as well as the same polytropic index γ = 5/3. Thus we investigated the role of physical viscosity in mass and angular momentum transport in the two viscid models and compare them to the inviscid model. An initial value of the parameter α = 1 has been considered for the physically viscous models, according to the well-known Shakura and Sunjaev formulation, but simulations were carried out also for α = 0.1 and α = 0.5 in the case of a supersonic mass transfer. Physical viscosity is represented by the viscous force contribution expressed by the divergence of the symmetric viscous stress tensor in the Navier-Stokes equation, while the viscous energy contribution is given by a symmetric combination of the symmetric shear tensor times the particle velocity. Results. The results show that physical viscosity supports and favours accretion disc formation despite the very low compressibility assumed. On the contrary, in the inviscid case no evident disc structure appears. In all models neither shock fronts nor extended clear spirals in the radial flow develop.

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“…This was part of the reason that the interest in spiral waves diminished after a series of landmark papers in the late eighties [23,24], and a solution to the angular momentum puzzle was sought in local magneto-turbulent processes [1]. In 1997, however, convincing observational evidence for tidally driven spirals in the disc of a CV was found for the first time.…”

Section: Prospect For Detecting Spiral Waves In Discsmentioning

confidence: 99%

Spiral Waves in Accretion Discs— Observations

Steeghs

2001

Astrotomography

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Abstract. I review the observational evidence for spiral structure in the accretion discs of cataclysmic variables (CVs). Doppler tomography is ideally suited to resolve and map such co-rotating patterns and allows a straightforward comparison with theory. The dwarf nova IP Pegasi presents the best studied case, carrying two spiral arms in a wide range of emission lines throughout its outbursts. Both arms appear at the locations where tidally driven spiral waves are expected, with the arm closest to the gas stream weaker in the lines compared to the arm closest to the companion. Eclipse data indicates sub-Keplerian velocities in the outer disc. The dramatic disc structure changes in dwarf novae on timescales of days to weeks, provide unique opportunities for our understanding of angular momentum transport and the role of density waves on the structure of accretion discs. I present an extension to the Doppler tomography technique that relaxes one of the basic assumptions of tomography, and is able to map modulated emission sources. This extension allows us to fit anisotropic emission from, for example, spiral shocks, the irradiated companion star and disc-stream interaction sites.

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Spiral shocks and accretion in discs

Cited by 106 publications

References 0 publications

Relativistic Dynamics and Mass Exchange in Binary Black Hole Mini-disks

Relativistic Dynamics and Mass Exchange in Binary Black Hole Mini-disks

Low compressibility accretion disc formation in close binaries: the role of physical viscosity

Spiral Waves in Accretion Discs— Observations

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