Talk:Relativistic jet

Copyright infringement
Image:Galaxies_AGN_Inner-Structure-of.jpg

Does not have permission of authors of original scientific article to be published here.

Please delete.

Mr Brak 19:12, 13 April 2006 (UTC)


 * You originally uploaded this image and as creator released it (licensed it) under the GFDL. Are you now wishing to retract this? -- Curps 04:31, 14 April 2006 (UTC)

Yes. It was originally published in a paper with numerous authors. I don't have permission of the other authors to use it here. I didn't realize this was an issue when I originally uploaded it.

Mr Brak 02:20, 16 April 2006 (UTC)

At the moment this article is really just a diagram. I am planning on adding more text and explanations of this diagram soon.

Layman copy needed
"Collimates" isn't a common word. It wasn't in my vocabulary, at least. Could we have a better explanation for the layman? What exactly makes matter shoot out in these jets, in language I will understand? —RadRafe 13:49, 2 Apr 2005 (UTC)


 * Plasma physics - electrical universe - cosmology - doesn't believe in black holes and has different explanations for the jets. They start with wondering why a black hole which is supposed to be sucking everything in sight is expelling massive jets of plasma and radiation. I am just starting to study this so I am not competent to explain why they think all of the active nuclei galaxies can be explained as electrical effects - powerful electrical structures explain the features without the need of mythical black holes which only have validity in certain mathematical computations. This appears to me to be a more interesting avenue of exploration.


 * What? Who says black holes are mythical?  By our understanding of the fundamental forces, whenever the gravity that a very massive object exerts on itself ceases to be countered by internal pressure, it is compressed to something smaller than its own Schwarzschild radius.  That's a black hole.  For black holes to not exist, there must be another pressure effect which kicks in after thermal pressure, radiation pressure,  and electron and neutron degeneracy pressure have all failed to stabilise a collapsing object.  We don't know of any mechanism that would produce such a pressure and save the thing.  Black holes must exist. —RadRafe | t 10:08, 2 May 2005 (UTC)


 * plasma doesn't say anything directly about black holes. That's more the province of general relativity - which firmly predicts such objects.  (So does Newtonian gravity, but it gives a different mass threshold.)  Look near the end of the black hole article for an account of models of supermassive objects without singularities.  The mainstream physics community supports black holes.  (Actually, to be more precise, the theories of gravity don't say that black holes exist, they only say that they're possible and that if they exist they have certain properties observed as common to galactic nuclei and other dense astrophysical objects.  Plasma physics might say something about the ways in which a dense star could collapse to form a black hole, but there are a lot of unknowns there.)
 * Even though nothing can escape from inside a black hole's event horizon, several sorts of radiation are emitted from just outside it. These include both the relativistic jets and Hawking radiation.  The former have been observed, while the latter is still theoretical.  (But is considered likely by mainstream physicists since the math looks good and the necessary observations are beyond current technology.)
 * The gravitational singularity at the center of a black hole might not be real, but that's not a big deal, since general relativity isn't expected to hold at lengths shorter than around the Planck length. (And singularity implies infinitesimal extent.  I.e., some variant on general relativity might allow the event horizon without the singularity.  Physicists find this idea comforting.
 * As for the definition of collimation: It means that the cone-shaped jets have a very narrow opening angle.  The width is something like 2% of the height.  The jets are very thin and long (for astronomical scales).SMesser 13:32, 11 May 2005 (UTC)

Needed
I seriously doubt weather there should be a "Relativistic Jet". IMHO it should eighter be merged with Jet, or renamed to Jet (astronomy).

Unsolved jet problem demystified
I replaced the unsolved problems in physics paragraph regarding relativistic jets with Williams' recognized applications of Penrose's black hole energy-momentum extraction mechanism. Tcisco 03:01, 13 April 2007 (UTC)

I have removed this as it is not generally accepted in the scientific community. The references you cited are poorly cited compared to other papers. Much debate about the nature and composition of jets continues. I have also removed the press release from Swift. Filling Wikipedia with press releases and peoples' pet theories is not good. Xioxox 20:15, 18 September 2007 (UTC)

Dr. Williams’ explanation for relativistic jets is verifiable and has been published by reliable third-party journals: Physical Review D and The Astrophysical Journal. Both these peer-reviewed scientific journals have a reputation of accuracy. Therefore, I have re-entered the text discarded by Xioxox, which was originally edited by Tcisco. I have included additional references: one to MHD models, the other to reliable black hole jet model supporting the explanation of Dr. Williams. Her explanation was re-entered so that the scientific community and society at large may have unbiased information available to them. Dr. Williams’ explanation is internationally known and accepted by many prominent scientists in the field of general relativity and relativistic astrophysics, including Sir Roger Penrose.

I am an expert in the field, and I know for a fact that Dr. Williams’ contributions over the past ten years have tremendously increased our understanding of rotating black hole physics and of the energy-momentum, relativistic-jet extraction process. Dr. Williams’ research is sound. In my opinion, there is no one in this somewhat narrow field of study more worthy than her to have their explanation mentioned in Wikipedia.Djily 01:35, 6 October 2007 (UTC)

You may claim to be an expert, but you need to back up the choice of this text with heavily cited papers. Can you cite a review article where this work is claimed to have solved any kind of problem? These papers have very little citation. I've been to dozens of talks by astrophysicists, work in a similar area to jets, and most claim that the origin of jets is an unsolved problem. I suggest if you wish to mention this theory, please add a section to the bottom and include it in a list of possible theories. You should not try to advance careers of individuals or theories by including comments in Wikipedia articles. I could probably produce a whole list of Jet papers from ApJ and so on - dozens are published every year. Xioxox —Preceding signed but undated comment was added at 09:52, 8 October 2007 (UTC)

Looking at ADS, I can only find a maximum of 8 citations for her most cited work on this subject. This is very small compared to most papers or authors in this field. Can you provide a paper with at least 50 citations on this subject? I can find other papers on ADS with hundreds of citations on jet formation mechanisms. Xioxox 10:07, 8 October 2007 (UTC)

Also, Niedzwiecki 2005 (MNRAS, 2005, 356, 913, http://arxiv.org/abs/astro-ph/0409710), states that Williams work is similar to a different study, and the conditions in her model may be unphysical and flawed. I suggest all references to different models be removed unless a review of all the different models is added to the page. It also appears that the article Gravitomagnetism may have too many references to her work. Xioxox 09:02, 9 October 2007 (UTC)

I've also found this interesting article, http://arxiv.org/abs/physics/0404029 where Dr Williams complains that her work is overlooked by her peers, which appears to claim it is due to her race. The paper shows her work is very controversial and not accepted by other scientists. Xioxox 09:08, 9 October 2007 (UTC)

In the article (http://arxiv.org/abs/physics/0404029), it appears that Dr. Williams is not complaining about her peers overlooking her work, but that some particular peers are using her work, specifically black hole physics derived in Williams (1995, Physical Review D, 51, 5387), and are not citing her manuscript as the originator. In Williams (1995) she gives the first detailed analytical 4-dimensional general relativistic spacetime description of particle orbits or trajectories about Kerr (rotating) black holes.Djily 07:13, 14 October 2007 (UTC)

Nowhere in the reference Niedzwiecki 2005 (MNRAS, 2005, 356, 913, http://arxiv.org/abs/astro-ph/0409710) cited by Xioxox is there a mentioning that Dr. Williams’ explanation is unphysical or flawed. In fact, the results of this paper support the validity of Dr. Williams’ model.Djily 22:19, 11 October 2007 (UTC)

Sorry - the astro-ph article is not the same as the published one. Try this http://adsabs.harvard.edu/abs/2005MNRAS.356..913N See page 923, section 5.1. Xioxox 09:27, 12 October 2007 (UTC)

After looking carefully at Williams’ (1995), 41 page, ''Phys. Rev. D'' publication, it appears that she laid the groundwork needed to do efficient Penrose-Compton scattering processes (as well as other Penrose processes considered by her), for other authors to follow and extend as did Niedzwiecki 2005 (MNRAS, 2005, 356, 913, http://arxiv.org/abs/astro-ph/0409710). Her scattering processes considered radii between r = 1.09 - 1.2, in units used by Niedzwiecki, whereas he considered radii ≥ 1.4. Both Williams and Niedzwiecki considered equatorial target electrons; the hard X-ray spectra produced by these authors were comparable and consistent with one another [see Table I, p. 5413 of Williams (1995)]. Williams considered, in addition, nonequatorially confined electron targets that have spherical-like orbits that pass through the equatorial plane repeatedly, as described by Carter (Phys. Rev. , 1968, 174, 1559). Williams derived analytical expressions for conserved energies and angular momenta of trajectories of such orbits, which include the orbits above the equatorial plane considered by Niedzwiecki. At r < 1.2, of course these orbits are unstable, but they are marginally bound. Unstable in this sense of general relativity means that for a small perturbation a test particle will either escape to infinity or fall into the black hole—just the condition it appears needed for effective Penrose processes.

These nonequatorially confined orbits are neither “unphysical nor flawed’’; neither was this terminology ever used by Niedzwiecki in reference to Williams’ work. In appears that Niedzwiecki’s statement that these nonequatorial orbits “obviously unbound” was presumed and not a fact. Further, it appears that Williams assumed that these nonequatorial orbits were from a corona surrounding the accretion disk just as Niedzwiecki assumed; the only difference is that Williams considered these orbits as they passed through the equatorial plane at r ≤ 1.2 and Niedzwiecki considered them at an angle above the equatorial plane at r ≥ 1.4, while assuming the corona to be corotating with the disk so that the equatorial orbital energies could be used for the target electrons. As for the statement made by Niedzwieck concerning Williams not considering the scattering probability, it appears that she does, by assuming the electron target energies cut off at about 12 MeV, allowing photons to escape with maximum energies of order 12 MeV.

In summary, it appears that there is nothing unphysical or flawed about Dr. Williams’ explanation. I sincerely hope we can clear up this matter soon with all fairness being extended to Dr. Williams, giving credit where it is due.Djily 02:14, 13 October 2007 (UTC)

Oh come on. This is ridiculous. Williams has virtually no citations for her work on this subject. Even she says "But, whatever the case maybe, the supporters of the Blandford-Znajek (BZ) model of today, Blandford, in particular, and his collaborators, continue to promote this model, even with the aged-old problem of converting from electromagnetic energy to relativistic particle energy, not to mention the general relativistic problems (see Williams 1999b and references therein). Now, I find nothing wrong with their continued support of BZ-type models. It is only when these supporters publish researched work from my paper (Williams 1995) in which I describe in details gravitational physics near the event horizon; yet, they do not appropriately reference my manuscript: this is where the problem lies." http://arxiv.org/abs/physics/0404029 Here she admits there are other competing theories for relativistic jet formation. Why does the article imply she has solved the problem?

And also "It seems that they are suppressing my successful, competing model—that can extract energy from a black hole—by masking my model, while using black hole physics originated from my manuscript, attempting to make BZ-type models work. Such behavior, of not references my work, has resulted in other authors taking credit for black hole physics devised by me." (same reference) Here she says that few other scientists in her field cite her work (as is obvious from ADS). Therefore few other scientists in her field think her work is important.

Her model is not worthy for mentioning (as it is not recognised) unless you want to do a proper review of all the competing models. In addition the non neutral point of view statements need to removed from the text (you shouldn't be making all those biased citations). There are many scientists working on MHD theories. For example, McKinney (2006), who does MHD simulations has 44 citations - many more times than Williams work. Xioxox 18:43, 13 October 2007 (UTC)

Okay - I've editing the text to make the point of view neutral. It read like an attack on MHD models before, which we both know are much more commonly used. I've included Penrose and Blandford-Znajek processes. I've tried to avoid going into too much detail here. Perhaps you could put the pros and cons of the Penrose and BZ mechanisms in their own pages if you want to. I think it now meets the Wikipedia NPOV standards now. Xioxox 19:12, 13 October 2007 (UTC)

I believe that we have reached a compromise. Your edit yields fairness to all. I have included in the list of references Williams (2004, The Astrophysical Journal, 611, 952-963. http://arxiv.org/abs/astro-ph/0404135). This is the important paper that ties her previous work of producing relativistic particles observed to be present in the jets (Williams 1995, Physical Review D, 51, 5387) to detailed creation /collimation of the jets. That is, these manuscripts form a complete package: the information presented in both is equally important in describing the relativistic jets produced by the Penrose mechanism.

Finally, one cannot but wonder, “What if Williams’ claim that some competitor peers in the past did not appropriately cite her work, leading to credit being given to others, is accurate?”  This might provide a reason today for her lack of citations, while her competitors have many.Djily 10:36, 14 October 2007 (UTC)

Electrical neutrality
The article writes about jets, that they "have long been known to be electrically neutral". What is this inferring?
 * Is it suggesting that because they contain equal numbers of proton and electrons, they are electrically neutral overall?
 * Or is it saying that although plasmas are quasi-neutral, jets are actually completely neutral?
 * That there are no electric fields or electric currents present... even though a current flowing through a wire is electrically neutral?
 * That there is no charge separation, even though equal charge separation would still imply electrical neutrality overall? --211.178.81.118 16:54, 17 September 2007 (UTC)

Origin of Jet
Relativistic jets are commonly observed in radio-loud systems.Now my question is that how do you know the origin of emission of relativistic jet is lying at the centre of the system? —Preceding unsigned comment added by 68.100.45.64 (talk) 04:21, 22 September 2007 (UTC)

Are you asking this question because you know a lot about this subject? High resolution radio analysis shows the jets originate from milliarcsec form the point-like compact objects, the supermassive black hole in the centres of galaxies. I'll revert this unless you want to refer to something which disagrees with this. Xioxox 16:42, 23 September 2007 (UTC)

Have you guys taken a look at the theory of dipole gravity? My name is Eue Jin Jeong the author of the theory of dipole gravity. If neutron stars can produce jets, the plasma and magnetic field caused jet theory must be false. Look how simply the theory of dipole gravity can explain jets as well as the dark matter problems. Just visit the [dipole gravity web blog] --Tachyonics (talk) 09:59, 28 January 2008 (UTC)

The reason Jeong’s hypothesis does not belong here, besides the questionable physics I address below, is that the so-called theory of Jeong is not considered as one of the competing models. Both the Blandford-Znajek and Penrose mechanisms and subsequent tests of these models have been published in numerous peer review refereed journals. In addition, these models have been cited by numerous authors working in the field of relativistic jets. I cannot find one place where Jeong’s paper has been cited by another author, except once in another "dead-end paper which exists nowhere but the arXiv" (see Wikipedia website given below).

After reading details of Jeong’s model claiming to produce relativistic jets, I conclude that his model is confusing and misleading. Jeong claims that he is using general relativity, and uses the term “gravito magnetism” as being another name for his so-called dipole gravity. This is very misleading since gravitomagnetism, as related to the Lense-Thirring effect  (or frame dragging), is a well known general relativistic phenomenon, with physical properties very different from what Jeong calls gravito magnetism. It is clear that Jeong is erroneously labeling components of his model with well known terms and conclusions in general relativity (GR) to make his model appear to be consistent with GR, when, in fact, it is not.

If Jeong wants his model to be accepted by the astrophysical community he needs to publish his work in refereed journals who have a reputation for fact-checking and accuracy, wherein his work can be reviewed by experts in the field. It appears that Jeong has not done this. Only through publications and citations will his work be considered as one of the “competing theories”; therefore, I have once again removed his model from this category. The Wikipedia is to inform the community, not to confuse them. It is not a place to have to argue the validity of a model or theory (peer review scientific journals are the place for that); neither is it the place to publish one's personal beliefs.

Moreover, please refer to Jeong’s contributions at (Wikipedia:Articles for deletion) to see that Jeong’s model of  “dipole antigravity,” which  he now refers to as “dipole gravity,” was deemed unfit for Wikipedia, citing serious flaws in his paper. Thus, based on all that has been said above, I now consider this matter closed. Djily (talk) 08:32, 30 January 2008 (UTC)

The dipole gravity paper has been published in the refereed journal Physica Scripta in 1999(http://www.tachyonics.com/physica.pdf). It is the Swedish journal published by the Swedish Royal Academy of Sciences that decides who gets the Nobel prize each year. The reason the paper has not been cited is because people do not understand what it is. I don't see why it is confusing if you take a look at it carefully. It would be the simplest theory of the relativistic jets known today. Basically, it is the theory of the additional long range gravity next to Newtonian gravity derived from the linearized theory of general relativity. Think about the possibility that you have been missing the additional fundamental long range gravity force.

If you take a look at the length of the jets from the both poles of the rotating black holes, you can tell immediately why the plasma and the magnetic field can not be the cause of it. The observed length of the both jets are basically the same. If the magnetic field and plasma are responsible for the jets, one side has to be shorter by at least a factor of 1836. This is the most favorable condition because it assumes that the jet materials are totally made of the hydrogen atoms. But if those jet are made of the materials heavier than the hydrogen atoms, the short side of the jets will be totally invisible because it will be shorter by the factor of 3672, 5508 etc.

This is a simple consequence of Newtonian dynamics, ie, if you have the same force in the system, the heavier the object, the lesser distance it travels inversely proportional to the mass of the projectile. And the plasma and the magnetic field can not shoot the both type (positive and negative) of particles in the same direction. Of course, this is a simple consequence of the Maxwell's equation. If you assume, by some kind of miracle, that the same number of positrons can be created at the core of the accretion disc, you may be able to explain the symmetric jets, but what is the probability for such a large number of poisitrons can be created equally as the number of electrons?

I'm tired of this silly game of deletion and undo nonsense. No one in the astrophysics community considers the problem of the relativistic jets has been completely solved.

It is not a bad idea letting people know of the unconventional theory but which may be the real solution to the relativistic jet problem. Because it also offers an excellent solution to the dark matter problems as well. To my best knowledge, no one has claimed a theory that can explain both the jets and the dark matter problem at the same time. Tachyonics (talk) 04:33, 26 February 2008 (UTC)

Name?
The article doesn't explain the name "relativistic jet", or what "relativistic" means. I think relativistic means "moving at a significant fraction of the speed of light" and therefore a relativistic jet is a jet of material moving at relativistic speeds. Is that right? If so could someone who actually knows about these things add a sentence to that effect to the article? Captain Chaos (talk) 14:57, 8 January 2009 (UTC)

Yes, that's correct. "Relativistic" speeds refer to speeds at which the effects of Relativity (as opposed to classical/Newtonian mechanics) become significant. 72.187.145.13 (talk) 22:16, 4 April 2009 (UTC)

Lorentz factor
According to this, a "Lorentz factor of ~100" would be faster than the speed of light. Should this article say "Lorentz factors of ~22.366" or something else, such as "speeds of ~.99995c" (and then I'd love to see a citation for that)? 72.164.134.11 (talk) 20:31, 19 April 2011 (UTC)

Should be merged with Polar Jet
A relativistic jet is just a very big, very fast polar jet. I can't see any rationale at all for them having separate articles. Someone has even put "Not to be confused with relativistic jet, a polar jet emitted at relativistic speed" at the start of the polar jet article. On the contrary, they should be potentially confusable (as long as you realise that all relativistic jets are polar but not all polar jets are relativistic). You could even make a case for merging with bipolar outflow, though that has other differences (non-ionised gas rather than plasma, non-collimated etc). Silent Key (talk) 04:40, 20 August 2012 (UTC)