Formation of jets with accretion disks at black holes

In summary: Mmmm, yes, after some reference searching I get the feeling that my hope of a sketch of the physical process "on the back of an enevelope" is a bit naive.I was hoping to get some feeling of why there are jets in the first place, and how its direction(s) roughly are determined.This may not be so easy - I don't think the phenomenon is completely understood.At first order, things are simple. If the source is surrounded by an orbiting disk, you get absorbtion in the disk-ward direction and thus transmission perpendicular to that. The problem is that jets seem to be narrower and more energetic than that simple model.I don't think
  • #1

haushofer

Science Advisor
Insights Author
2,928
1,465
TL;DR Summary
Looking for resources on the formation of jets at black holes
Dear all,

I'm going to give a course about black holes at an astrophysics association. The public will consist mainly of lay persons, perhaps wit a little bit of physics background. My background in General Relativity is good, but my background in astrophysics at bit less. My question is if you know about some good online resources/lecture notes about the formation of jets (and accretion discs) around black holes, and the mechanisms behind those jets launching charged particles. Is there an intuitive/easy way to understand how those jets form in the first place? Many thanks.
 
  • Like
Likes vanhees71
Astronomy news on Phys.org
  • #2
This may not be so easy - I don't think the phenomenon is completely understood.

At first order, things are simple. If the source is surrounded by an orbiting disk, you get absorbtion in the disk-ward direction and thus transmission perpendicular to that. The problem is that jets seem to be narrower and more energetic than that simple model.

I don't think there is any model that reproduces all the observed features. Shock seems to be involved, ant multi-component fluids (electrons do this, ions do that). Certainly magnetic fields by themselves won't do the trick.

Wasn;t there an Annual Review on jets a few years back?
 
  • Like
Likes vanhees71
  • #3
I concur that your task is far from simple. The only postulated mechanisms that I am aware of for formation of relativistic jets are the Penrose process and the Blandford-Znajek mechanism.

The first is based on frame-dragging, the second on a magnetized accretion disk with rotational contortions of the field lines.
 
  • Like
Likes vanhees71
  • #4
Hyperfine said:
I concur that your task is far from simple. The only postulated mechanisms that I am aware of for formation of relativistic jets are the Penrose process and the Blandford-Znajek mechanism.

The first is based on frame-dragging, the second on a magnetized accretion disk with rotational contortions of the field lines.
Mmmm, yes, after some reference searching I get the feeling that my hope of a sketch of the physical process "on the back of an enevelope" is a bit naive. I was hoping to get some feeling of why there are jets in the first place, and how its direction(s) roughly are determined.
 
  • Like
Likes vanhees71
  • #5
Vanadium 50 said:
This may not be so easy - I don't think the phenomenon is completely understood.

At first order, things are simple. If the source is surrounded by an orbiting disk, you get absorbtion in the disk-ward direction and thus transmission perpendicular to that. The problem is that jets seem to be narrower and more energetic than that simple model.

I don't think there is any model that reproduces all the observed features. Shock seems to be involved, ant multi-component fluids (electrons do this, ions do that). Certainly magnetic fields by themselves won't do the trick.

Wasn;t there an Annual Review on jets a few years back?
You mean

https://www.annualreviews.org/doi/pdf/10.1146/annurev-astro-081817-051948
?
That's behind a paywall, unfortunately.
 
  • #6
haushofer said:
behind a paywall
Unless you need it now, that's what libraries are for,

But why not just giove them the first order explanation perhaps adding "reality is far more complicated and not entirely understood".
 
  • #9
Vanadium 50 said:
Unless you need it now, that's what libraries are for,

But why not just giove them the first order explanation perhaps adding "reality is far more complicated and not entirely understood".
Yeah, sure, it's mostly for my own understanding. I'm just a bit surprised that my intuition falls short here, so I guess I learned something new :P
 
  • Like
Likes Hyperfine
  • #11
Neutron stars also have relativistic jets. A black hole is not a requirement. One may easily find images of the jets from the neutron star in the Crab Nebula. We know it has a neutron star because it is a pulsar. A black hole cannot be a pulsar.

I know that there is as yet no completely satisfactory explanation of relativistic jets. That is, an entirely successful model has yet to be built.
 
  • Like
Likes vanhees71
  • #12
Old habits die hard - likewise old models. People still say that nothing can get out of a black hole but Hawking changed that many years ago (1970s).
 
  • Like
Likes vanhees71

1. What is the process of jet formation at black holes?

The formation of jets at black holes is a result of the interaction between the black hole's strong gravitational pull and the surrounding accretion disk. As matter from the disk falls towards the black hole, it becomes superheated and accelerated, eventually being ejected from the poles of the black hole in the form of high-speed jets.

2. How do accretion disks contribute to jet formation?

Accretion disks are rotating disks of gas and dust that surround black holes. As matter from the disk spirals towards the black hole, it releases gravitational potential energy, causing the particles to heat up and accelerate. This acceleration is what drives the formation of jets at the poles of the black hole.

3. What factors influence the formation and behavior of jets at black holes?

The formation and behavior of jets at black holes are influenced by a variety of factors, including the mass and spin of the black hole, the strength and direction of the magnetic field, and the properties of the surrounding accretion disk. These factors can affect the speed, direction, and intensity of the jets.

4. Can jets at black holes be observed from Earth?

Yes, jets at black holes can be observed from Earth using different types of telescopes and instruments. For example, radio telescopes can detect the synchrotron radiation emitted by high-speed particles in the jets, while X-ray telescopes can capture the emission from the hot gas in the accretion disk. These observations help scientists better understand the formation and behavior of jets at black holes.

5. What role do jets play in the evolution of black holes?

Jets play a crucial role in the evolution of black holes by removing excess angular momentum from the surrounding accretion disk. This allows more matter to fall towards the black hole, increasing its mass and helping it grow larger over time. Jets also impact the surrounding environment, injecting energy and momentum into the surrounding gas and influencing the growth of galaxies and clusters of galaxies.

Suggested for: Formation of jets with accretion disks at black holes

2
Replies
63
Views
2K
Replies
23
Views
1K
Replies
12
Views
1K
Replies
2
Views
835
Replies
5
Views
1K
Replies
13
Views
1K
Replies
3
Views
821
Replies
2
Views
1K
Back
Top