Standing Shocks around Black Holes: An Analytical Study

Das, Santabrata; Chattopadhyay, Indranil; Chakrabarti, Sandip K.

doi:10.1086/321692

Cited by 53 publications

(56 citation statements)

References 22 publications

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“…However, not all inner shock solutions display preshock deceleration, and this is one basic difference between our disk dynamical profiles and the ones studied by Nakayama (1992Nakayama ( , 1994, Nobuta & Hanawa (1994), Chakrabarti & Molteni (1993), and Gu & Lu (2006). Furthermore, this result was never discussed by Chakrabarti (1989), Das et al (2001), or Le & Becker (2005) because different disk structures for different (ℓ,  -) parameter values were never examined in detail.…”

Section: Steady-state Solutionscontrasting

confidence: 57%

“…Inviscid and viscous advection-dominated accretion flows (ADAFs) have been shown to display shocked solutions (e.g., Chakrabarti 1989; Kafatos & Yang 1994;Lu & Yuan 1997;Das et al 2001;Le & Becker 2005;Das et al 2009), and the possibility that shock instabilities may generate the QPOs observed in some sources containing BHs has been pointed out by a number of authors(e.g., Chakrabarti & Molteni 1995;Lanzafame et al 1998;Titarchuk & Wood 2002;Aoki et al 2004;Chakrabarti et al 2009). Furthermore, shock stability analysis for thin disks has been studied using both analytical(e.g., Chakrabarti & Molteni 1993;Nakayama 1992Nakayama , 1994Nobuta & Hanawa 1994;Molteni et al 1996;Gu & Lu 2006;Nagakura & Yamada 2009) and numerical simulation approaches(e.g., Chakrabarti & Molteni 1993;Nobuta & Hanawa 1994;Molteni et al 1996;Gu & Lu 2006;Nagakura & Yamada 2008).…”

Section: Introductionmentioning

confidence: 99%

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Standing Shock Instability in Advection-Dominated Accretion Flows

Wood

Wolff

et al. 2016

ApJ

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Depending on the values of the energy and angular momentum per unit mass in the gas supplied at large radii, inviscid advection-dominated accretion flows can display velocity profiles with either preshock deceleration or preshock acceleration. Nakayama has shown that these two types of flow configurations are expected to have different stability properties. By employing the Chevalier & Imamura linearization method and the Nakayama instability boundary conditions, we discover that there are regions of parameterspace where disks/shocks with outflows can be stable or unstable. In regions of instability, we find that preshock deceleration is always unstable to the zeroth mode with zero frequency of oscillation, but is always stable to the fundamental mode and overtones. Furthermore, we also find that preshock acceleration is always unstable to the zeroth modeand that the fundamental mode and overtones become increasingly less stable as the shock location moves away from the horizon when the disk half-height expands above ∼12 gravitational radii at the shock radius. In regions of stability, we demonstrate the zeroth mode to be stable for the velocity profiles that exhibit preshock acceleration and deceleration. Moreover, for models that are linearly unstable, our model suggests the possible existence of quasiperiodic oscillations (QPOs) with ratios 2:3 and 3:5. These ratios are believed to occur in stellar and supermassive black hole candidates, for example, in GRS 1915+105 and Sgr A * , respectively. We expect that similar QPO ratios also exist in regions of stable shocks.

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Section: Steady-state Solutionscontrasting

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Standing Shock Instability in Advection-Dominated Accretion Flows

Wood

Wolff

et al. 2016

ApJ

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“…This we do analytically following the recently developed procedure of obtaining shock locations (Das et al 2001). By dynamically mixing these two components using solutions of the viscous transonic flows we obtain the specific energy and angular momentum of the sub-Keplerian region.…”

Section: Introductionmentioning

confidence: 99%

Computation of outflow rates from accretion disks around black holes

Das

Chattopadhyay

Nandi

et al. 2001

A&A

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Abstract. We self-consistently estimate the outflow rate from the accretion rates of an accretion disk around a black hole in which both the Keplerian and the sub-Keplerian matter flows simultaneously. While Keplerian matter supplies soft-photons, hot sub-Keplerian matter supplies thermal electrons. The temperature of the hot electrons is decided by the degree of inverse Comptonization of the soft photons. If we consider only thermallydriven flows from the centrifugal pressure-supported boundary layer around a black hole, we find that when the thermal electrons are cooled down, either because of the absence of the boundary layer (low compression ratio), or when the surface of the boundary layer is formed very far away, the outflow rate is negligible. For an intermediate size of this boundary layer the outflow rate is maximal. Since the temperature of the thermal electrons also decides the spectral state of a black hole, we predict that the outflow rate should be directly related to the spectral state.

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“…(13-16) from the sonic point once inward up to the black hole horizon and then outward up to a large distance (equivalently 'disc outer edge') and finally join them to obtain a complete global transonic accretion solution. Depending on the input parameters, flow may possess single or multiple sonic points (Das et al 2001a). When the sonic points form close to the horizon, they are called as inner sonic points (xin) and when they form far away from the horizon, they are called as outer sonic points (xout), respectively.…”

Section: Global Accretion Solutionmentioning

confidence: 99%

“…Solutions particularly of this kind are potentially interesting as they may possess centrifugally supported shock waves. The presence of shock wave in an accretion flow has profound implications as it satisfactorily delineates the spectral and temporal behaviour of numerous black hole sources (Chakrabarti 1989(Chakrabarti , 1990Molteni et al 1994Molteni et al , 1996Becker & Kazanas 2001;Lu et al 1999;Das et al 2001a;Le & Becker 2004;Gu & Lu 2004;Le & Becker 2005;Becker et al 2008;Nagakura & Yamada 2009;Nandi et al 2012;Das et al 2009Das et al , 2014Okuda 2014;Iyer et al 2015;Okuda & Das 2015;Aktar et al 2015;Suková & Janiuk 2015). Thus, in this work we intend to study the properties of magnetically supported accretion solutions that possesses shock waves.…”

Section: Shock Free Global Accretion Solutionmentioning

confidence: 99%

Dynamical structure of magnetized dissipative accretion flow around black holes

Sarkar¹,

Das²

2016

Mon. Not. R. Astron. Soc.

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We study the global structure of optically thin, advection dominated, magnetized accretion flow around black holes. We consider the magnetic field to be turbulent in nature and dominated by the toroidal component. With this, we obtain the complete set of accretion solutions for dissipative flows where bremsstrahlung process is regarded as the dominant cooling mechanism. We show that rotating magnetized accretion flow experiences virtual barrier around black hole due to centrifugal repulsion that can trigger the discontinuous transition of the flow variables in the form of shock waves. We examine the properties of the shock waves and find that the dynamics of the postshock corona (PSC) is controlled by the flow parameters, namely viscosity, cooling rate and strength of the magnetic field, respectively. We separate the effective region of the parameter space for standing shock and observe that shock can form for wide range of flow parameters. We obtain the critical viscosity parameter that allows global accretion solutions including shocks. We estimate the energy dissipation at the PSC from where a part of the accreting matter can deflect as outflows and jets. We compare the maximum energy that could be extracted from the PSC and the observed radio luminosity values for several super-massive black hole sources and the observational implications of our present analysis are discussed.

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Standing Shocks around Black Holes: An Analytical Study

Cited by 53 publications

References 22 publications

Standing Shock Instability in Advection-Dominated Accretion Flows

Standing Shock Instability in Advection-Dominated Accretion Flows

Computation of outflow rates from accretion disks around black holes

Dynamical structure of magnetized dissipative accretion flow around black holes

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