Computation of outflow rates from accretion disks around black holes

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

doi:10.1051/0004-6361:20011307

Cited by 59 publications

(62 citation statements)

References 9 publications

(22 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…4(b), we observe that only stronger shocks survive when α is increased. Most interestingly, as already shown for inviscid flows in Chakrabarti (1999) and Das et al (2001), the highest outflow rate is not necessarily seen when the shock is of highest strength. A balance of the CENBOL size and the energy available at the shock plays a major role in deciding this interesting behaviour.…”

Section: When Outflows Are Presentsupporting

confidence: 51%

Viscosity parameter in dissipative accretion flows with mass outflow around black holes

Nagarkoti

Chakrabarti

2016

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

Numerical hydrodynamic simulation of inviscid and viscous flows have shown that significant outflows could be produced from the CENtrifugal pressure supported BOundary Layer or CENBOL of an advective disk. However, this barrier is weakened in presence of viscosity, more so, if there are explicit energy dissipations at the boundary layer itself. We study effects of viscosity and energy dissipation theoretically on the outflow rate and show that as the viscosity or energy dissipation (or both) rises, the prospect of formation of outflows is greatly reduced, thereby verifying results obtained through observations and numerical simulations. Indeed, we find that in a dissipative viscous flow, shocks in presence of outflows can be produced only if the Shakura-Sunyaev viscosity parameter α is less than 0.2. This is a direct consequence of modification of the Rankine-Hugoniot relation across the shock in a viscous flow, when the energy dissipation and mass loss in the form of outflows from the post-shock region are included. If we ignore the effects of mass loss altogether, the standing dissipative shocks in viscous flows may occur only if α < 0.27. These limits are tighter than the absolute limit of α = 0.3 valid for a situation when the shock itself neither dissipates energy nor any outflow is formed. We compute typical viscosity parameters required to understand spectral and temporal properties of several black hole candidates such as GX399-4, MAXI J1659-152 and MAXI J1836-194 and find that required α are indeed well within our prescribed limit.

show abstract

Section: When Outflows Are Presentsupporting

confidence: 51%

Viscosity parameter in dissipative accretion flows with mass outflow around black holes

Nagarkoti

Chakrabarti

2016

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

show abstract

“…Moreover, a large number of authors have shown the formation of bipolar outflows from the post-shock accretion flow, both numerically (Molteni et al 1994(Molteni et al , 1996b as well as analytically (Le & Becker 2005;Chattopadhyay & Das 2007;Fukumura & Kazanas 2007;Das & Chattopadhyay 2008;Das et al 2009;Kumar et al , 2014. It is also interesting to note that, by considering a simplified inviscid accretion, and which has the right parameters to form a standing shock, Das et al (2001) qualitatively showed that there would be no jets in no-shock or weak shock condition of the disc, or in other words, when the disc is in the soft spectral state. This indicates the conclusions of Gallo et al (2003).…”

Section: Introductionmentioning

confidence: 97%

Periodic mass loss from viscous accretion flows around black holes

Das

Chattopadhyay

Nandi

et al. 2014

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We investigate the behaviour of low angular momentum viscous accretion flows around black holes using Smooth Particle Hydrodynamics (SPH) method. Earlier, it has been observed that in a significant part of the energy and angular momentum parameter space, rotating transonic accretion flow undergoes shock transition before entering in to the black hole and a part of the post-shock matter is ejected as bipolar outflows, which are supposed to be the precursor of relativistic jets. In this work, we simulate accretion flows having injection parameters from the inviscid shock parameter space, and study the response of viscosity on them. With the increase of viscosity, shock becomes time dependent and starts to oscillate when the viscosity parameter crosses its critical value. As a result, the in falling matter inside the post-shock region exhibits quasi-periodic variations and causes periodic ejection of matter from the inner disc as outflows. In addition, the same hot and dense post-shock matter emits high energy radiation and the emanating photon flux also modulates quasi-periodically. Assuming a ten solar mass black hole, the corresponding power density spectrum peaks at the fundamental frequency of few Hz followed by multiple harmonics. This feature is very common in several outbursting black hole candidates. We discuss the implications of such periodic variations.

show abstract

“…Hence matter in PSC is heated up and also it gets compressed. Since PSC is hot and compressed compared to the pre-shock matter, it develops an excess thermal gradient force which drives a part of the accreting matter as bidirectional jets/outflows (Chakrabarti 1999;Das et al 2001b;Chattopadhyay & Das 2007;Singh & Chakrabarti 2011;Kumar & Chattopadhyay 2013; Das et al 2014a,b;Aktar et al 2015). The soft photons from the outer disc interact with the hot electrons in the PSC and are inverse Comptonized to higher energies producing observable hard photons (Chakrabarti & Titarchuk 1995;Mandal & Chakrabarti 2005;Chakrabarti & Mandal 2006).…”

Section: Introductionmentioning

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

View full text Add to dashboard Cite

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.

show abstract

Computation of outflow rates from accretion disks around black holes

Cited by 59 publications

References 9 publications

Viscosity parameter in dissipative accretion flows with mass outflow around black holes

Viscosity parameter in dissipative accretion flows with mass outflow around black holes

Periodic mass loss from viscous accretion flows around black holes

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

Contact Info

Product

Resources

About