Questions tagged [accretion-disk]

An accretion disk is the disk around a compact star that accumulates matter from e.g. a companion star by the Roche lobe overflow or stellar wind transfer.

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How can we physically interpret the “boundary layer” at the inner edge of an accretion disk?

I am reading the paper Boundary-layer behavior of the flow at the inner edge of black hole accretion disks where the description of the accretion flow across the inner edge of the accretion disk (at ...
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I have a couple of questions regarding the physics of planet Miller and the black hole it's orbiting from the movie “Interstellar” [closed]

I watched the movie and thoroughly enjoyed it. I had a couple of questions regarding the physics, so I looked for answers. I got them, but I was left even more questions. I know that a lot of these ...
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What are some good resources to learn accretion processes around black holes?

I am interested in accretion processes around black holes and so I am looking for some comprehensive resources aimed at beginning graduate level. I came across two review papers, Foundations of Black ...
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Accretion disk velocity

Can matter in the accretion disk of a black hole, travel at superluminal velocities? If not, why? I know from the laws of special relativity that objects can never reach or exceed the speed of light, ...
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How do you estimate the accretion rate onto a black hole (or neutron star)?

Assume we have a heavy mass like black hole and there is an accretion disk around it. At a black hole (eg. pics of the bh. of m87) some parts of the given disk glows brighter than the others. How can ...
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Some doubts regarding the Paczynsky-Wiita potential for modeling accretion disk around Schwarzschild black holes?

I am presently studying accretion processes around Schwarzschild black holes and for this purpose I am reading the classic paper by Paczynsky and Wiita (1980). In this paper, the authors define the ...
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Is an exact description of accretion flow possible very close to a Schwarzschild black hole?

While modelling accretion disks around Schwarzschild black holes, various pseudo-Newtonian potentials are prescribed and then compared to general relativistic results. Though the pseudo-Newtonian ...
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Physical importance of centrifugal force and Coriolis force in the context of the restricted 3-body problem

In the textbook Galactic Dynamics (Binney and Tremaine), the restricted three-body problem to find the trajectory of a test mass that orbits in the combined gravitational field of two masses $M$ and $...
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What happens to the accretion disk when two black holes merge?

I'm aware that accretion disks around black holes are formed from the swirling mass of matter that is slowly being stripped of its atoms, but what happens to it when two black holes merge? I was ...
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Does space have inertia or mass regarding rotating black holes?

As I understood when a astronomical object such gass, planet or star reaches the proximity of a black hole it doesn't exhibit stright motion but a spiral aproximation towards the collapsed body of ...
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AGN accretion disk double peak explained?

I have a question to the following lecture: https://ned.ipac.caltech.edu/level5/Fabian4/Fab2_2.html In Figure 3 it says that a narrow annuli of a Newtonian disk should alrdy show a double peak ...
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Effective potential for Kerr geometry

In the review Foundations of Black Hole Accretion Disk Theory, the authors defines an effective potential for Kerr geometry as (Chap. 2, eqn. 23) $$\mathcal{U}_{eff}=-\frac{1}{2}\ln\left|g^{tt}-2lg^{t\...
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Newtonian/Relativistic Solutions of Fluid Disks in orbit around a massive body

I have been trying to make an RMHD (Relativistic Magneto-Hydro Dynamics) Set-up of a Disk around a Massive Rotational Body. The initial paper I have been studing a paper which uses a Fishbone & ...
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Physical significance of angular velocity of orbits around Kerr black holes

For the Kerr metric $$ds^2=\left(g_{tt}-\frac{g_{t\phi}^2}{g_{\phi\phi}}\right)dt^2+g_{\phi\phi}\left(d\phi-\omega dt\right)^2+g_{rr}dr^2+g_{\theta\theta}d\theta^2$$ the angular momentum is defined as ...
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What are Quasi-Periodic Oscilations and how can they be used to determine the mass of black holes?

Quasi-Periodic Oscillations (QPOs) are observed in almost all accreting systems and they provide an essential tool to explore accretion flows from compact objects. But I couldn't understand what ...
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Four-momentum of a photon emitted from an accretion disk

Consider a non-rotating compact object surrounded by a revolving accretion disk. A distant observer sees the disk in an edge-on position. The center of the disk may be taken as the origin of $r-\theta-...
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How can a gas be in circular orbit when centrifugal force is dominant in an accretion disk around a black hole?

In the textbook "Black Holes, White Dwarfs and Neutron Stars: The Physics of Compact Objects" by Shapiro and Teukolsky, the author makes the following statement while discussing the standard thin disk ...
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Disk-like structures spectra vs ring spectra?

In the introduction to this paper (https://arxiv.org/abs/1803.06423) it is mentioned that disk-like spectra was observed in black hole X-ray binaries, when models would expected to be unstable (...
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What causes the heating of a black hole's accretion disk?

Sheperd Doeleman said in a TED video that the accretion disk is heated by friction. Is that correct? I thought it might be adiabatic heating from the compression of the gasses.
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Can Compton scattering increase a photon's energy?

I've read (in Hagai Netzer's book The Physics and Evolution of Active Galactic Nuclei) that "Comptonization in the [black hole's accretion] disk atmosphere can increase the energy of some photons..." [...
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Understanding the notion of lose or win of angular momentum in accretion disk

Here is below a slide of one of my lecture in planetology : I understand well the fact that ring A will be slow down by friction with ring B since ring B is rotating slower and the inverse process (...
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Wind-fed Accretion and White Dwarf stars

Can a White Dwarf star in a binary system accrete matter via the Wind-fed accretion process?
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Does infalling material leaves a detectable imprint on the black hole's event horizon?

An external observer will never see anything cross the event horizon, and in most explanations the story ends here. But I wonder what happens with gravitational effects of the material? For example ...
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Putting the importance of the blackhole image into perspective [closed]

The recent astonishing achievement of obtaining an actual image of a blackhole, resulted from a massive collaborative work using 8 different telescopes and the equally on par efforts in developing the ...
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Why isn't the circumferential light around the M87 black hole's event horizon symmetric?

After the revelation of the first black hole images, it seems there is a bias towards the south side. Is it because of measuring it from earth or is it something more fundamental in the understanding ...
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How can write physics in terms of local rest frame?

Many times I saw that people wrote that we write the equations in terms of local rest frame, for example in the paper of Novikov and Thorne that calculated stress-energy tensor for Kerr blackhole ...
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How to calculate the corotation radius?

I am studying this paper: P.Ghosh & F.K.Lamb, APJ, 232, pag.259 (1979) I do not understand how the authors calculate the corotation radius, $r_{co}$, where the matter of the disk has the same ...
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If you fell into a black whole with an accretion disc, but perpendicular

If you fell into a black whole with an accretion disc, but orthogonal to the plane of the disc - would you ever meet the disc? I'm not asking whether you survive long enough, and obviously we assume ...
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How can a galaxy not be disk shaped [closed]

If a galaxy is the accretion disk for a supermassive black hole, how can it be a shape other than disk?
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Neutron Star LMXB Accretion Spin-Up Estimation

I've been asked to estimate how much mass a neutron star in a low mass X-ray binary would have to accrete in order to be spun up to ~300 Hz. I found the conservation formula $\frac{d(I\omega)}{dt} = \...
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Why does the accretion disc radiate energy and matter?

Jets of matter and energy are powered by accretion disc i.e., matter spiralling into the massive black hole at the galactic centre. How is this jet formed? I think that the dust particles and gases ...
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Is the average temperature of a big accretion disk colder than a small one?

Suppose we have a Shakura and Sunyaev style accretion disk between $r_1$ and $r_2$. What is the average temperature? We can calculate it by integrating the local temperature $$T(r)=\left [ \frac{3GM\...
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What is episodic accretion in star formation?

When I think about "episodic accretion", I imagine material from an envelope accreting only sometimes. Is that the right meaning of episodic accretion? or does it mean that the accretion rate is ...
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Resources in magnetized accretion disk

I'm looking for some resources in magnetized accretion disk. Preferably a book or an article review that starts with un-magnetized accretion disk theory. While I have some familiarity with accretion ...
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What is the density profile of Sagittarius A*'s accretion disk?

It is thought that Sagittarius A*, the supermassive black hole at the center of the Milky Way, is surrounded by an accretion disk. Can anyone provide a resource for the general density profile of ...
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Need advice on thin accretion disk model

I'm a physics teacher and I'm building a simple accretion disk model to show to students in an astrophysics class (undergraduate level), as an exemple of physics modeling. I need to know if this ...
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Paradox from mass transfer in a close stellar binary

I'm considering a simple binary system made of two stars, of mass $m_1$ and $m_2 < m_1$, on circular orbits around their center of mass. Using Newton's theory of gravitation, it is easy to prove ...
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Why can't friction in an accretion disk radiate away enough of the angular momentum do create inward spiral?

As almost every source that I'd found explains, it was a challenge for scientists to understand the mechanism by which the total angular momentum in the accretion disc was conserved, while taking the ...
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Accretion neutron star; mass gain 0.8m?

My textbook on Astrophysics says the following about accretion (translation): Assume we have a particle with mass $m$ that falls on a neutron star; $R\approx 10$ km, $M\approx 1.4M_{\text{sun}}$, ...
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overstability vs resonance: what is the difference?

Reading about discs, I encountered the word 'overstability' that its difference with resonance is not clear to me. Does anyone know the difference?
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What is the jet luminosity of this quasar (ULAS J1120+0641)?

In wikipedia I found that its luminosity is $6.3×10^{13}$ solar luminosities, but is that the luminosity of the jet itself or is that the luminosity of the entire system (the jet + the accretion disk) ...
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841 views

The difference between sub-Eddington and super-Eddington accretion disk models

I am studying accretion disks around active galactic nuclei (AGN). I have seen two sets of models, sub-Eddington and super-Eddington accretion disks. What do these terms refer to in this case? I ...
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Viscous accretion disk, green formula

I have this problem. I am studying a the viscous accretion disk problem and in the assumption of constant viscosity the equation of diffusion of the superficial density becomes: $$ \frac{\partial}{\...
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Why does most galaxies resemble a 2 dimensional plane? [duplicate]

Older galaxies mostly tend the revolve forming a disk. Why are the stars not revolving around the center of the galaxy like a sphere instead similar to electron in an atom?
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387 views

Luminosity of an accretion disk?

With reference to Black holes in particular, how can you approximate the luminosity of an accretion disk? It is possible to quantify the temperature at a given point, but as the disk is not a black ...
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Direction of Gamma Ray Bursts

After a black hole consumes a star, why do gamma ray bursts only shoot out perpendicular to the spinning accretion disk? Why do they not shoot out parallel to the disk?
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Black hole accretion disks and quasars

Are 'accretion disk of a black hole' and 'quasar' synonymous? If not, what's the difference?
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Black hole corona and bipolar outflows

What are black hole coronas? Are they different from accretion disks? If so, how are they formed?
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Black hole accretion disk

Does matter in a black hole's accretion disk eventually fall into the black hole? If no new matter is added to disk, how long does it take or the black hole to consume the entire accretion disk?
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Dependence of the magneto-rotational instability (MRI) on thermal relaxation?

The MRI is the most efficient driver of turbulence in accretion discs (as measured by the effective scalar stress). The magnetic field, being properly coupled to the gas (weak coupling), connects the ...