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.
89 questions
1
vote
0
answers
22
views
Effects of turbulence on black hole accretion disks
Most of the analytical studies of accretion disks around black holes usually ignore the effects of turbulence. However, results of numerical simulations suggest that turbulence plays a crucial role in ...
- 2,065
0
votes
0
answers
59
views
What is the shape of neutron star?
What would be the shape of a fast spinning neutron star?
Can it be a disk?
Or just a Saturn-like ring?
Or would it take the shape of the sun?
- 31
0
votes
2
answers
47
views
Origin of Angular Momentum in Accretion disk formation
I read this paper, Formation of the Asymmetric Accretion Disk from Stellar Wind Accretion in an S-type Symbiotic Star, I didn't quite understand where the angular momentum came from.
Where I'm ...
- 31
0
votes
0
answers
8
views
What angle would frame dragging shove matter in the innermost accretion disk relative to the equatorial plane or orbit?
I understand that frame dragging will imbue momentum on plasma orbiting a black hole at close range.
My first question is - is this kinetic energy inserted very narrowly relative to the equatorial ...
- 1
1
vote
0
answers
60
views
Does a white hole forms accretion disk?
A white is time reversal of a blackhole at least mathematically, I know it can't exist but may I know if it can form accretion disc similar to those stellar mass black holes. Does it spins on it's ...
- 13.1k
1
vote
0
answers
59
views
Should we expect lightning-like phenomena as matter enters the accretion disk of a black hole?
As matter enters the accretion disk it will rapidly turn into superheated plasma. I would expect this to coincide with lightning-like phenomena due to the electric potential difference between this ...
- 1,805
2
votes
0
answers
44
views
Would an ionized accretion disk experience radial charge separation?
(Sorry if I'm using the wrong terms, but I've yet to find any search terms that seem related to what I'm thinking of. If I did know what to search for, I wouldn't be asking this question.)
Would an ...
- 1,304
0
votes
1
answer
148
views
Perfect Conducting (PC) and Perfect Insulating (PI) boundary conditions for magnetic induction in MHD problems in cylindrical coordinates
I understand the computational implementation of the PC and PI bcs in cartesian case. In terms of the magnetic field components for PI, we have $B_x = B_y = B_z = 0$, and for PC, we have $B_x = \...
- 23
2
votes
0
answers
45
views
Are these star - black hole binary pair illustrations art or physics?
It seems that every illustration of a black hole pulling matter off a star looks like this one from the Chandra X-ray Observatory website.
Or this one from Nature - Two black holes found in a star ...
- 45.6k
1
vote
1
answer
50
views
Space mission for experimental verification of frame-dragging in the strong-gravity limit
Frame-dragging is an important general relativistic effect that has been observed in the weak-field limit by the Gravity Probe B experiment for the gravitational field of the Earth.
Although the ...
- 2,065
0
votes
1
answer
107
views
Can stars gravitationally shield a black hole?
Is it possible to arrange a set of massive objects such as stars in orbit around a black hole such that objects of lesser mass cannot physically reach and fall into the event horizon of the black hole?...
6
votes
1
answer
196
views
Why don’t black rings exist in 3+1 dimensions?
In higher dimensions black holes can take different forms. Besides spheroids, there are also “black rings” which have a toroidal event horizon. However, in our 3+1 dimension no black ring solution has ...
- 1,537
-1
votes
2
answers
77
views
Star gets eaten and spit out?
How does material get swallowed and torn apart by a black hole and have its light vanish. But somehow the same material escapes years later. After its light couldn't even escape?
They watched it for ...
1
vote
0
answers
46
views
How would the Redshift of a Photon be influenced if it travels through a volumetric gas disk?
so me and a buddy have been working on a Black Hole render engine for quiet a while now. And at this point we have most of the technical stuff worked out. Which results in images like these;
Note, ...
- 308
5
votes
1
answer
35
views
Why is the common envelope ejected in some accretor-donor systems?
As an example, let us consider a binary system of a neutron star and an evolved star (e.g. red giant) that has expanded, filled its roche lobe, and started the mass transfer onto the neutron star.
...
- 95
1
vote
2
answers
403
views
Why is the photon sphere spherical, but the accretion disk not?
As far as I understand, photons are massless, but are still subject to gravity, must follow the distortions of spacetime (including framedragging etc.), period.
Now the only answer on this site ...
- 29.3k
1
vote
1
answer
112
views
What does a black hole accretion disk look like edge on?
We have images of two black holes so far, with representations showing a deep black center where in-falling matter vanishes- how would that look side on? Would it be possible to even obtain an image ...
- 39
1
vote
0
answers
64
views
What determines the black hole accretion rate?
There is clearly a natural timescale to accrete matter around a black hole given by the balance of pressure and gravity, known as the Eddington luminosity. However, as I understand it, this is really ...
- 1,301
1
vote
1
answer
82
views
Rotating black hole
I know that everything that is shaped from gravity force is rotating, and gravity is a central force. but I want to know how can we detect that a black hole has an angular momentum? By which ...
- 39
3
votes
1
answer
360
views
Neutrinos and black holes
As a new user I could not comment on Do neutrinos of any flavor get trapped in black holes?
My question is that the Ice Cube facility has mapped Neutrinos coming from black holes, as stated in ...
6
votes
0
answers
82
views
Improving physics simulation of black hole accretion disk?
I have recently been working on software which uses ray tracing/marching to render a black hole in the Schwarzchild metric. I've implemented most everything that I originally set out to do, and I am ...
0
votes
1
answer
37
views
If the BH accretion disk rotates near the speed of light should its EM-radiation in direction of rotation be highly blueshifted?
If the BH accretion disk rotates near the speed of light should its EM-radiation in direction of rotation be highly blueshifted? Maybe gamma blushifted if there weren't gravitational redshift?
- 2,275
0
votes
0
answers
57
views
Circular gravitational field
Why do all heavy masses in the universe always have circular gravitational field and why do objects 'falling' under their spacetime influence always fall in circles? For example, accretion disks ...
2
votes
0
answers
39
views
Would a black hole act as a particle accelerator between the photon sphere and the event horizon?
I'm trying to understand the behavior of photons between the photon sphere and the event horizon. Here is what I think I understand so far :
the radius of the PS is 1.5 times the Schwarzschild radius
...
- 21
5
votes
2
answers
158
views
Is accretion disc caused by frame dragging?
Is accretion disc around a Kerr black hole the result of its frame dragging?
- 1,248
2
votes
1
answer
72
views
What happens when a cool brown dwarf slowly accretes matter?
Let's imagine that we take a brown dwarf close to the minimum mass of a red dwarf.
Then let's allow it a few quadrillion years to cool.
Finally slowly accrete matter at a rate of say 1 Jupiter mass ...
- 3,001
1
vote
1
answer
76
views
What happens when a helium white dwarf accretes enough matter?
What happens when a helium white dwarf accretes enough matter?
Say you have a white dwarf made of helium, what happens when it's core becomes dense enough to fuse helium and how massive would it have ...
- 3,001
2
votes
1
answer
840
views
Is a fusion process possible inside an accretion disk?
Is a fusion process possible inside an accretion disk? As the speed of matter inside an accretion disk approaches the speed of light can an incoming object collide with the disk material and cause a ...
- 1,835
3
votes
1
answer
75
views
How can supersonic accretion flows exist in astrophysical scenarios?
I often hear about supersonic accretion flows in astrophysical scenarios: for example, the inner parts of the accretion disk around a supermassive black hole or cold filaments accreting into galaxies ...
- 205
0
votes
0
answers
34
views
Does some of accretion disk light make focal points above the black hole poles? [duplicate]
Does some of accretion disk light make focal points above the black hole poles?
- 1,835
1
vote
0
answers
81
views
Does the latest picture of EHT mean the end to the no hair theorem?
I couldn't help but noticing what looks like "hair" in the latest image from EHT.
Does this mean the end of the no hair theorem?
Pun intended but also a serious question.
- 26.6k
0
votes
0
answers
58
views
What ranges of $l$ and $m$ give the spherical harmonics for disk features?
The spherical harmonics represent a spherically symmetric basis and correspond to the eigenfunction solutions of the three-dimensional Laplacian. They take the form
$$ Y_l^m(\theta,\phi) = \sqrt{\frac{...
- 472
1
vote
1
answer
68
views
Are the particles in the accretion disk in free fall around the black hole?
I know that black hole can feed off the material in the accretion disk and gain mass, the accretion disk is also powered by the black hole to move at a fraction of speed of light. I am wondering are ...
- 13.1k
1
vote
0
answers
154
views
Are there black holes without accretion disk but emitting astrophysical jets?
First a citation from Wikipedia page about relativistic jets:
"Jets may also be observed from spinning neutron stars. An example is pulsar IGR J11014-6103, which has the largest jet so far ...
- 1,835
1
vote
1
answer
162
views
Why does the jet come out perpendicular to the accretion disc?
Why does the jet always come out perpendicular to the plane of the accretion disc around a black hole?
- 12.3k
1
vote
2
answers
244
views
Is the Accretion Disk of a Black Hole just an illusion?
As a matter of fact, I recently learnt that as an object is approaching a black hole, to an outside observer the object seems to be getting slower and slower and will cross the event horizon after an ...
- 13
1
vote
1
answer
125
views
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 ...
- 11
1
vote
0
answers
30
views
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 ...
- 2,065
2
votes
0
answers
48
views
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 ...
- 2,065
1
vote
0
answers
151
views
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 $...
- 2,065
4
votes
3
answers
280
views
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 ...
- 87
1
vote
1
answer
117
views
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 ...
- 11
5
votes
1
answer
749
views
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\...
- 2,065
0
votes
0
answers
33
views
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 & ...
- 231
3
votes
1
answer
432
views
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 ...
- 133
1
vote
0
answers
29
views
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 ...
- 133
0
votes
1
answer
70
views
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-...
- 329
2
votes
1
answer
114
views
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 ...
- 2,065
1
vote
0
answers
27
views
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 (...
- 43
3
votes
2
answers
211
views
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.
- 394