Study of relativistic accretion flow around KTN black hole with shocks

Sen, Gargi; Maity, Debaprasad; Das, Santabrata

doi:10.1088/1475-7516/2022/08/048

Cited by 7 publications

(5 citation statements)

References 87 publications

(108 reference statements)

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“…Indeed, it is evident that for higher a k , shock exists when the angular momentum of the flow is relatively low [67], and this happens due to the spin-orbit coupling present in the effective potential (see equation (1a)) describing the space-time geometry around the black hole. These findings are in agreement with the results of [36]. In contrary, we find that r s decreases due to the increase of θ for flows accreting onto a black hole having a fixed spin (a k ) value.…”

Section: Global Accretion Solutionssupporting

confidence: 93%

“…Because of this, inflowing matter must make sonic state transition from subsonic to supersonic smoothly at least once while accreting onto the black holes. Interestingly, depending on the flow parameters, namely energy and angular momentum, flow may encounter such sonic transitions multiple times, and solution of this kind is specially encouraging as the centrifugal barrier may trigger the discontinuous transition of the flow variables in the form of shock wave [5,[22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]. Such shock transitions are possible provided Rankine-Hugonoit standing shock conditions (RHC) are satisfied [38].…”

Section: Introductionmentioning

confidence: 99%

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Properties of relativistic hot accretion flow around a rotating black hole with radially varying viscosity

Singh,

Das

2024

Astrophys Space Sci

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We examine the effect of variable viscosity parameter (α) in relativistic, low angular momentum advective accretion flow around rotating black holes. Following the recent simulation studies of magnetohydrodynamic disk that reveal the radial variation of α(r), we theoretically investigate the properties of the global transonic accretion flow considering a one-dimensional power law prescription of viscosity parameter as α(r) ∝ r θ , where the viscosity exponent θ is a constant. In doing so, we adopt the relativistic equation of state and solve the fluid equations that govern the flow motion inside the disk. We find that depending on the flow parameters, accretion flow experiences centrifugally supported shock transition and such shocked accretion solutions continue to exist for wide ranges of the flow energy, angular momentum, accretion rate and viscosity exponent, respectively. Due to shock compression, the hot and dense post-shock flow (hereafter PSC) can produce the high energy radiations after reprocessing the soft photons from the pre-shock flow via inverse Comptonization. Since PSC is usually described using shock radius (rs), compression ratio (R) and shock strength (S), we study the role of θ in deciding rs, R and S, respectively. Moreover, we obtain the parameter space for shock and find that possibility of shock formation diminishes as θ is increased. Finally, we compute the limiting value of θ (i.e., θ max ) that admits shock and find that flow can sustain more viscosity when it accretes onto rapidly rotating (ak → 1) black hole in comparison to weakly rotating (ak → 0) black hole.

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Section: Global Accretion Solutionssupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Properties of relativistic hot accretion flow around a rotating black hole with radially varying viscosity

Singh,

Das

2024

Astrophys Space Sci

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“…The obtained results are shown in Figure 1(b). Note that we use a lower  value for higher a k simply because a low-angular-momentum flow () can only sustain shocks around rapidly rotating BHs (Dihingia et al 2019;Sen et al 2022). We observe that for Φ 13 = 0, the shock transition happens at a relatively smaller radius, at r sh = 6.525 (denoted by the dotted-dashed vertical arrow), compared to the nonspinning case.…”

Section: Shock-induced Global Grmhd Accretion Solutionsmentioning

confidence: 98%

“…Indeed, accretion solutions containing shocks are thermodynamically preferred due to their high entropy content (Becker & Kazanas 2001), which facilitates the explanation of the spectrotemporal signatures of BH X-ray binaries (Chakrabarti & Titarchuk 1995;Mandal & Chakrabarti 2005;Nandi et al 2012;Iyer et al 2015;Das et al 2021;Majumder et al 2022;Nandi et al 2024). After realizing the astrophysical significance, shock-induced accretion solutions have been studied both in hydrodynamics (Fukue 1987;Chakrabarti 1989;Yang & Kafatos 1995;Ryu et al 1997;Lu et al 1999;Das et al 2001Das et al , 2014Das et al , 2009Becker & Kazanas 2001;Fukumura & Tsuruta 2004;Das 2007;Becker et al 2008;Kumar et al 2013;Suková & Janiuk 2015;Suková et al 2017;Aktar et al 2017;Kim et al 2019;Dihingia et al 2019;Sen et al 2022) as well as MHD (Takahashi et al 2006;Fukumura et al , 2016Sarkar & Das 2015, 2016 scenarios. However, efforts are pending to investigate the accretion dynamics involving shocks in GRMHD flows around rotating BHs.…”

Section: Introductionmentioning

confidence: 99%

Low-angular-momentum General Relativistic Magnetohydrodynamic Accretion Flows around Rotating Black Holes with Shocks

Mitra,

Das

2024

ApJ

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We investigate the global structure of the general relativistic magnetohydrodynamic (GRMHD) accretion flows around Kerr black holes containing shock waves, where the disk is threaded by radial and toroidal magnetic fields. We self-consistently solve the GRMHD equations that govern the flow motion inside the disk and for the first time, to our knowledge, we obtain the shock-induced global GRMHD accretion solutions around weakly as well as rapidly rotating black holes for a set of fundamental flow parameters, such as energy ( E ), angular momentum ( L ), radial magnetic flux (Φ), and isorotation parameter (F). We show that shock properties—namely, the shock radius (r sh), compression ratio (R), and shock strength (Ψ)—strongly depend on E , L , Φ, and F. We observe that the shock in the GRMHD flow continues to exist for a wide range of the flow parameters, which allows us to identify the effective domain of the parameter space in the L – E plane where shock solutions are feasible. Moreover, we examine the modification of the shock parameter space and find that it shifts towards the lower-angular-momentum values with increasing Φ and black hole spin (a k). Finally, we compute the critical radial magnetic flux (Φcri) that admits shocks in GRMHD flows and ascertain that Φcri is higher (lower) for a black hole of spin a k = 0.99 (0.0) and vice versa.

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“…where θ 0 is the inclination angle of the accretion disc with respect to the distant observer direction, which is taken as 45 • [72,81]. To calculated u t , one has to use the standard time-like condition u k u k = −1.…”

Section: Bremsstrahlungmentioning

confidence: 99%

Accretion flow in deformed Kerr spacetime: spectral energy distributions from free-free emission

Patra,

Majhi,

Das

2024

J. Cosmol. Astropart. Phys.

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In this paper, we study the properties of accretion flow including its spectral features in Johannsen and Psaltis (JP) non-Kerr spacetime. In doing so, we numerically solve the governing equations that describe the flow motion around the compact objects in a general relativistic framework, where spin (ak ) and deformation parameters (ε) demonstrate the nature of the central source, namely black hole (BH) or naked singularity (NS). With this, we obtain all possible classes of global accretion solutions (i.e., O, A, W and I-type) by varying the energy (E) and angular momentum (λ) of the relativistic accretion flow, and examine the role of thermal bremsstrahlung emission in studying the spectral energy distributions (SEDs) of the accretion disc. We divide the parameter space in λ-E plane in terms of the different classes of accretion solutions for BH and NS models. We further calculate the disc luminosity (L) corresponding to these accretion solutions, and observe that I-type solutions yield higher L and SEDs than the remaining types of solutions for both BH and NS models. For BH model, SEDs for W and I-type solutions differ significantly from the results for O and A-type solutions for low E values. On the contrary, for NS model, SEDs for different accretion solutions are identical in the whole parameter space of λ and E. We also examine the effect of ε on the SEDs and observe that a non-Kerr BH yields higher SEDs than the usual Kerr BH. Finally, for accretion solutions of identical E and λ, we compare the SEDs obtained from BH and NS models, and find that naked singularity objects produce more luminous power spectra than the black holes.

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Study of relativistic accretion flow around KTN black hole with shocks

Cited by 7 publications

References 87 publications

Properties of relativistic hot accretion flow around a rotating black hole with radially varying viscosity

Properties of relativistic hot accretion flow around a rotating black hole with radially varying viscosity

Low-angular-momentum General Relativistic Magnetohydrodynamic Accretion Flows around Rotating Black Holes with Shocks

Accretion flow in deformed Kerr spacetime: spectral energy distributions from free-free emission

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