Standing Rankine-Hugoniot shocks in the hybrid model flows of the black hole accretion and winds

Chakrabarti, Sandip K.

doi:10.1086/168125

Cited by 301 publications

(434 citation statements)

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“…These shocks are non-dissipative in nature as the specific energy remains con- served across the shock front (Chakrabarti 1989). Indeed, shocks of this kind are radiatively inefficient as well.…”

Section: Global Accretion Solutionsmentioning

confidence: 99%

Properties of magnetically supported dissipative accretion flow around black holes with cooling effects

Sarkar

Das

Mandal

2017

Monthly Notices of the Royal Astronomical Society

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We investigate the global structure of the advection dominated accretion flow around a Schwarzschild black hole where the accretion disc is threaded by toroidal magnetic fields. We consider synchrotron radiative process as an effective cooling mechanism active in the flow. With this, we obtain the global transonic accretion solutions by exploring the variety of boundary conditions and dissipation parameters, namely accretion rate (ṁ) and viscosity (α B ). The fact that depending on the initial parameters, steady state accretion flows can possess centrifugally supported shock waves. These global shock solutions exist even when the level of dissipation is relatively high. We study the properties of shock waves and observe that the dynamics of the post-shock corona (hereafter, PSC) is regulated by the flow parameters. Interestingly, we find that shock solution disappears completely when the dissipation parameters exceed their critical values. We calculate the critical values of viscosity parameter (α cri B ) adopting the canonical values of adiabatic indices as γ = 4/3 (ultra-relativistic) and 1.5 (seminon-relativistic) and find that in the gas pressure dominated domain, α cri B ∼ 0.4 for γ = 4/3 and α cri B ∼ 0.27 for γ = 1.5, respectively. We further show that global shock solutions are relatively more luminous compared to the shock free solutions. Also, we have calculated the synchrotron spectra for shocked solutions. When the shock is considered to be dissipative in nature, it would have an important implication as the available energy at PSC can be utilized to power the outflowing matter escaped from PSC. Towards this, we calculate the maximum shock luminosity and discuss the observational implication of our present formalism.

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Section: Global Accretion Solutionsmentioning

confidence: 99%

Properties of magnetically supported dissipative accretion flow around black holes with cooling effects

Sarkar

Das

Mandal

2017

Monthly Notices of the Royal Astronomical Society

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“…The SPH method belongs to the so-called "shock-capturing" methods since the role of the artificial viscosity, in inviscid hydrodynamics, is to allow shocks to satisfy the Euler equation when discontinuities (shock or contact discontinuities) are present. In the case of "shock tracking" methods, a complete steady solution requires the equations of energy, angular momentum, and mass conservation to be supplemented by transonic conditions at some critical points and RH conditions at an unknown weak shock location (Chakrabarti 1989(Chakrabarti , 1990). Therefore such methods involve two different codes to solve Euler equations as for inviscid hydrodynamics.…”

Section: The Modelmentioning

confidence: 99%

The role of viscosity in AGN outflows in relation to jet periodicities

Lanzafame¹,

Cassaro

Schillirò

et al. 2008

A&A

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Aims. Adopting the Smoothed Particle Hydrodynamics (SPH) numerical method, we performed a grid of evolving models of a 3D axially-symmetric, viscous accretion disc around a supermassive black hole (SMBH) of 10 6 ÷ 10 9 M . Such sort of simulations are typical of accretion discs in active galactic nuclei (AGN). In such disc models, we pay attention to the role of the specific angular momentum λ and the turbulent viscosity parameter α, according to the Shakura and Sunyaev prescription. One or two shock fronts in the radial inviscid flow develop, according to the assigned initial kinematic and thermodynamic conditions. Methods. By fixing the initial and boundary conditions on the flow at the disc outer edge, where the total energy, the specific angular momentum λ, and the initial velocity are concerned, we find pairs of (α, λ) values determining radial periodical oscillations in the shock front. In some cases, an outflow develops from the subsonic post-shock region, close to the black hole. Results. The link between the accretion disc and the jet refueling through the onset of a centrifugal shock front is evident. We also compare model variability periods with observed ones in the radio light curves of AGN.

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“…From equations (1a-1d), the sonic point conditions are derived following the general procedure 12 and are given by,…”

Section: Sonic Point Conditionmentioning

confidence: 99%

Properties of Accretion Shocks in Viscous Flows With Cooling Effects

Das

Chakrabarti

2004

Int. J. Mod. Phys. D

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Low angular momentum accretion flows can have standing and oscillating shock waves. We study the region of the parameter space in which multiple sonic points occur in viscous flows in presence of various cooling effects such as bremsstrahlung and Comptonization. We also quantify the parameter space in which shocks are steady or oscillating. We find that cooling induces effects opposite to heating by viscosity even in modifying the topology of the solutions, though one can never be exactly balanced by the other due to their dissimilar dependence on dynamic and thermodynamic parameters. We show that beyond a critical value of cooling, the flow ceases to contain a shock wave.

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Standing Rankine-Hugoniot shocks in the hybrid model flows of the black hole accretion and winds

Cited by 301 publications

References 0 publications

Properties of magnetically supported dissipative accretion flow around black holes with cooling effects

Properties of magnetically supported dissipative accretion flow around black holes with cooling effects

The role of viscosity in AGN outflows in relation to jet periodicities

Properties of Accretion Shocks in Viscous Flows With Cooling Effects

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