What Data is Needed to Understand the Formation of Black Hole Jets?

[LewMcCoy]

Dear Internet-

As part of an introductory Astronomy course, it is time to compile a mock research proposal, specifically to give us an idea of what real scientists do. The purpose of it is to focus on a particular not-yet-understood phenomenon of astronomy, and describe the process we would use to gather such data.

I find the jets of black holes to be fascinating, and have come here for some expert advise. As I understand so far, we know what these jets are made of (photons & electrons), but the true mystery still lies in how they are formed. Exactly how are black holes, notorious for their unyielding gravity, able to propel matter at nearly the speed of light?

This is the foundation of my research so far. The question remaining yet is the type of data and observations we plan to gather and make to try and decipher this mystery. This is where I'm a bit confused: what exactly would benefit and clarify our understanding of these jets? Knowing more about the magnetic fields of black holes? Their composition? More about their masses? Temperature? The difficulty lies in connecting the phenomenon with data. Any guidance or advice is greatly appreciated.

Thank you!

 

[twofish-quant]

Exactly how are black holes, notorious for their unyielding gravity, able to propel matter at nearly the speed of light?

That's not quite the mystery. It's not the black hole that is causing the jets to form, but rather the magnetic field around the black hole. You see jets form around neutron stars, and it turns out we think it's the same process.

The really big mystery is how magnetic fields work for form jets. What you'd like to do is to come up with a model in which you put in the magnetic fields, lots of ionized gas, and then run a supercomputer simulation or calculate things on paper and pencil, and boom, you get a jet. We aren't at that level of understanding.

Part of the problem is that plasmas and magnetic fields are hard. Gravity is pretty easy. Things fall down. With plasmas and magnetic fields all sorts of complex things happen.

what exactly would benefit and clarify our understanding of these jets? Knowing more about the magnetic fields of black holes? Their composition? More about their masses? Temperature?

Yes. What we'd like to do that we can't is to look at a jet and say "based on my looking at this jet, I can tell that the temperature of the gas is X, the magnetic field strength is Y, etc. etc." We aren't anywhere close to there yet.

For example, one thing that would be useful is to be able to tell that the thing is producing a jet really is a black hole. It would be nice to say black hole jets look like X, and neutron star jets look like Y.

 

[LewMcCoy]

So bottom line, it would be very valuable to know if the process that creates jets from neutron stars/quasars is the same as that/those of black holes.

Question now is, how exactly do we begin study the magnetic fields of these jets from black holes?

And thanks for your help.

 

[Misericorde]

Could these kinds of jets be achieved on a small scale, in a fictional context only (I'm writing) as a kind of weapon? Does it take an engine as massive as a hunk of degenerate matter to produce the needed ejecta and magnetic fields?

 

[Imax]

Jet formation seems to be an outcome of rotating mass. Protostars, pulsars, and black holes all seem to have a common phenomenon, jet formation about an axis of rotation. A rotating mass can cause electron flow, causing a magnetic field, causing charged particles to flow along magnetic field lines. The problem with black holes is that the cause of jet formation has to occur outside the event horizon.

 

[Imax]

If the cause of jet formation has to occur outside the event horizon, then classical theory can’t explain jet formation around a black hole. Any electric field or magnetic filed generated from a central mass within the event horizon can’t influence events outside the event horizon, and can’t be the cause jet formation. Frame dragging about a black hole could explain jet formation.

 

[Misericorde]

If the cause of jet formation has to occur outside the event horizon, then classical theory can’t explain jet formation around a black hole. Any electric field or magnetic filed generated from a central mass within the event horizon can’t influence events outside the event horizon, and can’t be the cause jet formation. Frame dragging about a black hole could explain jet formation.

I don't see how this is correct. The mass of a black hole obviously has influence beyond the event horizon, so why not in this case?

 

[Polyrhythmic]

Any electric field or magnetic filed generated from a central mass within the event horizon can’t influence events outside the event horizon, [...]

This is not true. Electromagnetic fields of sources inside the horizon actually influence anything outside the horizon just as if the black hole wasn't there. This is due to the nature of the field, the interaction is transmitted by virtual photons which are not affected by the black hole's gravitational field. The same explanation is also valid for hypothetical gravitons. See this thread for more information: https://www.physicsforums.com/showthread.php?t=490924 .

 

[Imax]

In quantum mechanics, light is made up of photons, massless particles with an associated wavefunction. In classical mechanics, light is made up of electromagnetic radiation. The defining property of a back hole is that its escape velocity is greater than the speed of light. Classically, if electromagnetic radiation can’t escape a black hole, then how can electric or magnetic fields reach beyond the event horizon?

 

[Polyrhythmic]

Read again what I wrote. In Quantum Field Theory, fundamental interactions are transmitted by so called virtual particles. Virtual photons are not the same photons which light consists of, that are trapped inside a black hole. They do not feel the gravitational field.

 

[Imax]

In Quantum Field Theory, fundamental interactions are transmitted by so called virtual particles.

That's what I'm trying to say. Classical mechanics has a hard time explaining jet formation around a black hole. Without a comprehensive quantum field theory, explaining black hole jet formation is problematic. In the framework of general raltivity, electric or magnetic fileds generated from a central mass within the event horizon can’t influence events outside the event horizon.

 

[Imax]

This is probably too late for LewMcCoy’s term paper, but if electric or magnetic fields generated from a central mass within an event horizon can’t influence events outside the event horizon, an option at explaining jet formation around a black hole, within GR, is to consider frame dragging. There are stable orbits about a black hole within the Kerr metric. Stable orbit = mass accumulation = accretion disk. Jet formation about a black hole can be attributed to friction within the accretion disk, but I can’t see this process forming an intense jet stream about an axis of rotation.

 

[Discord7]

http://dalescosmos.blogspot.com/
I believe that electrostatic influence explains the electron beams. Negative charge developed within stars envelops galaxies. Negative charged particles are repelled to galactic rims, therefore positive charged particles converge to an inner region of positive charge. While this region holds shape of an open disk, electrons descend to rotational axis. They ignore the electron-sated black hole and launch by mutual repulsion along rotational axis guided by electron gun quite similar to many of our little ones in TV sets. Electrons maintain that axis by guidance to locus of equidistance to the positive rim of black hole's accretion disk. Intense heat developed with the converging of matter falling toward singularity might result in positron production to account for neutrinos coming out of the mix.

 

[Imax]

See http://arxiv.org/PS_cache/astro-ph/pdf/0404/0404135v3.pdf

 

[twofish-quant]

If the cause of jet formation has to occur outside the event horizon, then classical theory can’t explain jet formation around a black hole.

There's something called the membrane paradigm that translates GR's so that mere mortals can figure out what is going on. You can show that a black hole acts like a classical conducting sphere.

Any electric field or magnetic filed generated from a central mass within the event horizon can’t influence events outside the event horizon, and can’t be the cause jet formation.

So it's not generated from the central mass. :-) :-) :-)

 

[twofish-quant]

This is not true. Electromagnetic fields of sources inside the horizon actually influence anything outside the horizon just as if the black hole wasn't there.

Well... You could have the black hole develop a charge, but it's believed that this isn't what causes the magnetic field of the black hole. Like lots of things with black holes, the important stuff is caused by matter that is just about to fall into the black hole.

 

[Misericorde]

Do black hole's emit polar jets, or relativistic polar jets, or is there some factor of its mass or angular momentum of the accretion disc which determines that?

 

[Discord7]

Well... - - but it's believed that this isn't what causes the magnetic field of the black hole.

Wouldn't a rotating accretion disk or bulge, surrounding a black hole and bearing an electric charge produce a magnetic field that would be difficult to to discern from a magnetic field attributed to a black hole?

 

[Misericorde]

Wouldn't a rotating accretion disk or bulge, surrounding a black hole and bearing an electric charge produce a magnetic field that would be difficult to to discern from a magnetic field attributed to a black hole?

You can't discern that a black hole is charged from observation, but in the mathematics of them, a charge is allowed if infalling matter carries a charge. This charge is not the same thing as the powerful magnetic field caused by the action of the accretion disk; they are two separate concepts really.

 

[Imax]

Like lots of things with black holes, the important stuff is caused by matter that is just about to fall into the black hole.

I’m thinking that maybe not everything in the accretion disk that falls inwards towards the black hole singularity adds to black hole mass. Most of it may form a nice jet about an axis of rotation.

 

[twofish-quant]

Wouldn't a rotating accretion disk or bulge, surrounding a black hole and bearing an electric charge produce a magnetic field that would be difficult to to discern from a magnetic field attributed to a black hole?

The curious thing about astronomical objects is that it's hard for them to keep a charge going for long periods of time. If you have something that is positive charge it will attract negative charges, and then end up neutral.

The basic mechanism that we think powers most astronomical bodies is the dynamo effect, in which you have a conducting fluid that interacts with a magnetic field to sustain a magentic field, and yes the accretion disk does interact with the field in complicated ways.

 

[Imax]

Black holes are like bubbles in 4D space and time.

 

[Misericorde]

The curious thing about astronomical objects is that it's hard for them to keep a charge going for long periods of time. If you have something that is positive charge it will attract negative charges, and then end up neutral.

The basic mechanism that we think powers most astronomical bodies is the dynamo effect, in which you have a conducting fluid that interacts with a magnetic field to sustain a magentic field, and yes the accretion disk does interact with the field in complicated ways.

Isn't that supposed to be the same mechanism that generates our geomagnetic field? (our core as a dynamo)

 

[Discord7]

The curious thing about astronomical objects is that it's hard for them to keep a charge going for long periods of time. If you have something that is positive charge it will attract negative charges, and then end up neutral.

For an electrically isolated astronomical object in possession of a greater number of electrons than it does of protons, then we might tend to think of its concentration of electrons about its exterior as though it were a charge. However, that concentration of electrons would have gathered, propelled by exothermic migration, whereas a the process of charging something pertains more readily to results of an endothermic process. Those electrons can find no neutralizing protons to cancel their influence; they can rest only when spaced as far from each other as they can get.

Additions to such concentrations of electrons can occur by exothermic migration whenever an ionizing event displaces the charged portions of a molecule into sufficient mutual departure from each other so that the global outward repulsion for electrons exceeds the remaining mutual attraction of the molecular fractions for each other. Nothing new is suggested here about electrical particles. Simple reverse engineering should depict astronomical objects as bearing stable configurations of proton cores and outer coatings of electrons.

 

[twofish-quant]

Isn't that supposed to be the same mechanism that generates our geomagnetic field? (our core as a dynamo)

Exactly.

 

[Discord7]

You can't discern that a black hole is charged from observation, but in the mathematics of them, a charge is allowed if infalling matter carries a charge. This charge is not the same thing as the powerful magnetic field caused by the action of the accretion disk; they are two separate concepts really.

To clarify my question: Others have been referring to a magnetic field coming from a super-massive black hole. I deem the black hole a nonparticipant in the beam forming process and agree that the spinning accretion disk produces magnetism. The electron beams produced as polar jets are fed electro-statically to the rotational axis and held so, collimated in their outward trajectory by the positive polarization at the rim of the disk which serves in the identical fashion of a focusing anode within a common CRT's electron gun. Magnetic effects neither contribute to nor disrupt the electron beams that constitutes the only paths for electron departure from the incidental location of the black hole.

It stacks up that electrons are certainly available to the black hole, but preciously few of them are taken in. The black hole would have swallowed enough electrons so that its gravitational pull upon an electron would become equaled by its electrostatic repulsion for the same particle. Fancy a close-in electron straggling either way along the rotational axis, indifferent even to the infamous event horizon.

 

[Imax]

You could look at a black hole in GR like a closed 4-D space-time manifold. That could easily explain why light, or electromagnetic radiation, can’t escape.

Mass can bend light (i.e. microlensing) and space-time. Maybe space-time around a black hole singularity is so badly bent that it forms a closed manifold. That could easily explain why anything occurring within the event horizon can’t influence anything outside the event horizon. But, big problem. If space-time around a black hole singularity forms a closed 4-D space-time manifold, then anything occurring outside the event horizon can’t influence anything within the event horizon.

Maybe black holes rarely feed.

 

[twofish-quant]

To clarify my question: Others have been referring to a magnetic field coming from a super-massive black hole. I deem the black hole a nonparticipant in the beam forming process and agree that the spinning accretion disk produces magnetism.

Except that this doesn't work. Black holes do have strong magnetic fields. What happens is that if you have an electrically charges pellet, it "appears" to freeze as it falls into the black hole. If you start moving that pellet, then you get a magnetic field.

Google for "membrane paradigm thorne" for the details.

 

[Discord7]

Except that this doesn't work. Black holes do have strong magnetic fields. What happens is that if you have an electrically charges pellet, it "appears" to freeze as it falls into the black hole. If you start moving that pellet, then you get a magnetic field.

Google for "membrane paradigm thorne" for the details.

What is it that doesn't work? Although I doubt that many charged pellets would be falling into a black hole, it would nevertheless be beside any point I was making.

 

[cph]

Some more recent artistic depicts seem to emphasize more of a polarity to jet depiction (and formation)?