Talk:Quasar

Time dilation

Is there a specific reason that this isn't in the article?

http://mnras.oxfordjournals.org/content/405/3/1940

http://arxiv.org/abs/1004.1824

http://iopscience.iop.org/1538-4357/553/2/L97/fulltext/

Paradoctor (talk) 19:09, 14 October 2013 (UTC)

Yes: (a) the article can't describe everything that everyone has ever observed about quasars, and (b) there's no consensus that it's correct. Mhardcastle (talk) 07:42, 15 October 2013 (UTC)

(a) We are an encyclopedia, and this is research published in reputable peer-reviewed scientific journals.

(b) Lack of scientific consensus is not a reason for exclusion. Furthermore, to establish lack of consensus in this matter, we need either sources saying so outright, or papers attacking Hawkins' position. I'm not aware of either, maybe you can help me out here? Paradoctor (talk) 08:34, 15 October 2013 (UTC)

(a) Literally thousands of articles about quasars are published in peer-reviewed journals every year. We can't include everything that all of them say.

(b) Lack of consensus is a reason for excluding material in an article which necessarily has to summarize a huge literature. For arguments against Hawkins' work see e.g. Baganoff & Malkan (1995) ApJ 444 L13. Mhardcastle (talk) 19:46, 18 October 2013 (UTC)

Toroidal black holes

Removed the following text from the article pending discussion.

The extremely energetic outflows of quasars remain difficult to understand. Although a consensus exists that the central engine is a supermassive black hole, the assumption of a spheroidal event horizon has been questioned. A toroidal black hole carrying a modest electrical charge would give rise to a magnetic dipole most intense within the central aperture where the flux would be axially aligned and thus favourably oriented for the launching of biaxial jets. As the flux lines would locally run parallel to the toroidal event horizon, the black hole's charge would be relatively immune to neutralisation by the surrounding plasma of the accretion disk. Through dissipation of angular momentum and subsiding accretion, the toroidal aperture would eventually seal, abruptly depriving the black hole of its jet-forming magnetosphere. This scenario can naturally explain the permanent extinction of activity suggested by the observation of quasars almost exclusively at significant redshifts.

Here are the issues I see with this text:

• It's wrongly placed; it doesn't belong in the overview of quasars. ('Emission generation' might be better.) It assumes various things that are not discussed until later in the article.
• It discusses what is basically a fringe theory, based on a couple of papers with no citations in mainstream journals, and does so in great detail. If we want a discussion of jet generation in quasars (and it's not clear that this is where it should go: see also under relativistic jet), then it should give far more weight to widely used standard models such as Blandford-Znajek and Blandford-Payne, both of which clearly can generate jets.
• It implies that quasars are seen only at 'significant redshifts' but this is not true, and in particular powerful jets are common to redshift zero (see Cen A, M87 et al) and it is powerful jets, not quasars, that the model purports to explain.

This seems to have been added out of a real desire to improve the article, but I think it needs significant modification before it should be included.

Mhardcastle (talk) 08:17, 3 March 2014 (UTC)

• I agree - it would be better placed in emission generation.
• It is based on two papers published in mainstream journals whose conclusions have gone unchallenged for over a decade. Since the stability of toroidal black holes may well be due to quantum gravitational effects currently beyond our ken, the ideas do not readily lend themselves to further study just yet. Nevertheless, a toroidal black hole scenario has definite advantages over the more traditional alternative in its consistency with actual observational data. I note that the Blandford-Payne process gets no mention in polar jet, an article that states under "Unsolved problems in astrophysics: Why do the discs surrounding certain objects, such as the centers of active galaxies, emit radiation jets along their polar axes?". Let's not pretend that this is a solved problem. Simulations have found that although the B-Z process can indeed generate jets, but they are some 4 orders of magnitude weaker than some observations demand for the popping of corks.
• I have edited the snippet above in order to avoid giving the impression that it would have been impossible for quasars to persist until the present time, but I refer you to Schneider et al for a redshift histogram. Furthermore, the overview for this page actually begins with the words "Quasars show a very high redshift", which your editing has not touched.

Gofod (talk) 22:41, 3 March 2014 (UTC)

OK, I think you're agreeing with my first and third points, so let's talk about my second. I am not trying to claim that this is a solved problem, and any article on this should make that very clear. What I am saying is that, since this is an encyclopedia, we should give more weight to models that are actually used than models that are not. Papers that are not cited in the literature are not 'going unchallenged', they are being ignored. Therefore, a section on jet generation should talk about the mainstream models first and in more detail. Note that I am not saying that alternative models should not be mentioned at all, just that they shouldn't have the relative prominence that your text would have given them.

I'm not sure where you're getting the idea that B-Z can't generate the required power -- current simulations seem to suggest there's no problem -- see e.g. http://adsabs.harvard.edu/abs/2012MNRAS.423.3083M . I don't work on jet generation, but nobody I know in the jet generation community is talking about this as a problem.

I am not trying to suggest that the discussion in polar jet is complete -- on the contrary, that article is probably the one where one should start trying to improve the discussion of jet generation models on Wikipedia, since relativistic jets are not unique to quasars, or even observed in the vast majority of quasars. (Personally I have a certain reluctance to work on an article whose very title appears to have been chosen by someone who doesn't know the literature, but that's what we have to work with...)

Mhardcastle (talk) 08:00, 4 March 2014 (UTC)

Jets are arguably the most interesting features of quasars, especially since they can provide key clues to the central engines. I therefore think a section/subsection devoted to potential formation mechanisms of relativistic jets is warranted (not just "emissions"). As is clear from polar jet, not all jets are relativistic and bipolar jets are quite ubiquitous phenomena, some forming from stellar accretion for example. A discussion of toroidal black holes thus seems to me more apt here, though I accept that the emphasis should be more on more traditional efforts to explain the jets with references to the original B-Z paper and MNRAS 423 3083. After describing full 3-D simulations, the discussion of this latter paper states "A significant new result is that such models do show large-scale dipolar magnetic flux formation near the horizon. However, only weak transient highly magnetized relativistic jets emerge." It would seem that even Blandford and his colleagues recognise the difficulty pointed out by (i) Ghosh & Abramowicz and (ii) Livio, Ogilvie & Pringle. I would also remind you of the "unsolved problem" statement on polar jet.

A spinning, electrically charged toroidal black hole (TBH) holds is well-suited to the efficient generation of relativistic jets due to its ability to retain charge over the long-term and siphon plasma into the central aperture where axial jets can be launched along the magnetic flux lines leading away from the TBH. Furthermore, it offers a very compelling explanation for the finite lifetimes of quasars. This is difficult to explain otherwise as a good fraction of galaxies are found in galaxy clusters where most of the primordial hydrogen has yet to be reprocessed. TBH stability may demand some revision of existing theoretical assumptions but science is ultimately about marrying up theory and observation. In this respect the TBH scenario is superior to the SBH scenario both in terms of jet formation and quasar extinction. It represents an interesting and readily comprehensible alternative which, irrespective of current fashions in science, is notable on account of its improved consistency with empirical data. That is why this article ought to refer to it.

Gofod (talk) 23:20, 4 March 2014 (UTC)

Jets are indeed a very interesting feature of quasars, but (a) most quasars don't have them and (b) the vast, vast majority of SMBH-generated relativistic jets are seen in objects that are not classed as quasars (see e.g. radio galaxy). So, I stand by my point that this whole discussion would be better in some other article.

You are misreading the McKinney et al paper -- the conclusion you quote is true for a particular field configuration, and in fact the whole point of this paper is to show that for poloidally dominated fields in the accretion disk an efficient, persistent jet can emerge.

I'm afraid what you (or I) personally think about the viability of the TBH model is not the point, though, as I've said before, any model that predicts an absence of jet-generating black holes at z=0 is completely inconsistent with observation. Wikipedia policies require us to present a scientific discussion of this sort representing what is in the literature in proportion to its notability, i.e. to the extent which it's used in the community -- if you want to call that fashion, you're welcome, but it doesn't change the rules. If you want to promote this model, you need to write papers (or should I say 'more papers'?) about it and get them cited, not edit Wikipedia. See Wikipedia:Fringe theories, Wikipedia:Neutral point of view.

Mhardcastle (talk) 07:48, 5 March 2014 (UTC)

The visibility of the jets depends very much on their relative orientation to us, the redshift of the quasar and whether there is much influx of matter from an accretion disc at any given time. The TBH model does not predict the complete absence of jet-generating black holes (toroidal or otherwise) at z=0, it merely explains why the revival of relativistic jets is highly unlikely in SMBHs still subject to significant accretion - and many low redshift galaxies within galaxy clusters are still rich in gas.

As for the rules, I followed the first of your links and discovered the following one: "all majority and significant-minority views published in reliable sources should be represented fairly and proportionately". I thought that you understood this point when you wrote "Note that I am not saying that alternative models should not be mentioned at all, just that they shouldn't have the relative prominence that your text would have given them". You also accepted that the formation of relativistic jets is not a solved problem. If in the last day or two you have changed your mind, why have you not removed the "unsolved problem" comments from polar jet. You have repeatedly ignored this point (and dismissed the papers which attest to its existence) so allow me to paste what it says here:

List of unsolved problems in physics: Why do the discs surrounding certain objects, such as the centers of active galaxies, emit radiation jets along their polar axes?

An article on quasars that mentions relativistic jets but fails to discuss possible jet generation mechanisms is a rather superficial one - and Wikipedia is supposed to be an encyclopaedic source of information. The TBH model may not be widely known but it has two distinct advantages over more traditional models: powerful jets and abrupt extinction. Since science concerns reconciling observations with theory rather than adhering to the first theory that comes along (or indeed counting citations) and the TBH possibility has not been directly challenged in the literature, it clearly merits inclusion here. To omit it would be to flout Wikipedia's neutrality rules, which I note you have also seen fit to bring up.

Gofod (talk) 23:44, 5 March 2014 (UTC)

We're going in circles here. I have not at any point said that your model should not be discussed, just that it should not be given the prominence that your original text would have given it. If you agree, then that's fine. Feel free to start writing some text that does what we apparently both agree should be done. My most recent response was directed at your comments that implied that the TBH model was superior, and was intended to explain why your beliefs are essentially irrelevant to writing a Wikipedia article. You still appear to believe that any model that is 'unchallenged' (i.e. that nobody has bothered to test) should be covered here, which is clearly incorrect.

I have not 'repeatedly ignored' the fact that this is an unsolved question: in fact I've explicitly acknowledged it in every comment I've made on this topic. I don't know why you feel the need to take this confrontational attitude or to attribute to me things I clearly haven't said.

Mhardcastle (talk) 07:57, 6 March 2014 (UTC)

Mamas 2011 - any notability or non-fringe-ness?

An IP user keeps adding a reference to Mamas 2011, which looks to me to be WP:FRINGE, and uncited thus not notable. Are there any citations to this work, or any reliable third party references to it? I certainly couldn't find any in a quick google search.

In response to the IP editor's recent edit summary, "Mamas' article is 2011 which is why it is not yet cited in the literature.": here's an example of a paper on quasar emission modelling from 2011 with 30 citations. This was found after 20 seconds of ADS searching (even so, I see no need to include a reference to it in this article). If Mamas's work is notable, it should have received some citations somewhere in the last 3 years.

I wonder if the IP editor's repeated insertion of this citation into this, and the GRB article, is a example of self promotion? - Parejkoj (talk) 13:52, 14 May 2014 (UTC)

It is historical fact that in the early years of quasar discovery, the leading concept was that quasars were matter-antimatter phenomena. That this idea is still defendable can and should be noted. I suggest Parejkoj first read Mamas' article. The article is published in peer-reviewed journal and so was examined by independent astronomers before publication. 96.228.244.95 (talk) 15:01, 14 May 2014 (UTC)

I agree that this looks rather like fringe material; the edit summaries ("Antimatter does not fit with big bang astronomy which is why Parejkoj is frighted by it.") are not the helping the case either. Rather than referring to the supposed correctness of the Mamas paper, the only relevant defense should be demonstrating that this is mainstream enough to warrant a mention here per WP:UNDUE, like references and citations, thus far not provided. siafu (talk) 15:21, 14 May 2014 (UTC)

The phrasing admits it is a minority opinion: At this time, there were some suggestions that quasars were made of some hitherto unknown form of stable antimatter and that this might account for their brightness, an hypothesis still defended by some[24].

But as a minority opinion with historical precedent it should not be censored because it does not fit with the big bang theory. 96.228.244.95 (talk) 16:31, 14 May 2014 (UTC)

You have to demonstrate that this is a significant minority view, and not just a fringe view. It has nothing to do with the fact that it does or not fit with the current theory. siafu (talk) 17:10, 14 May 2014 (UTC)

The view that matter-antimatter was the power of quasars was commonplace in the early years of the discovery of quasars, and therefore a significant hypothesis. The view is developed by Mamas giving solid observational evidence, using updated modern observational evidence. It is not to be censored by supporters of the big bang theory. 96.228.244.95 (talk) 18:18, 14 May 2014 (UTC)

Again, this has nothing to do with censorship. Please provide references demonstrating that this is a significant minority view, and not just a single fringe individual. Otherwise, I don't see any reason for including mention of Mamas' work, end of discussion. siafu (talk) 18:29, 14 May 2014 (UTC)

It is admitted right in Wikipedia's own article that the antimatter-matter hypothesis was significant, significant enough to be included in Wikipedia's own article, where, quote, At this time, there were some suggestions that quasars were made of some hitherto unknown form of stable antimatter and that this might account for their brightness... 96.228.244.95 (talk) 18:54, 14 May 2014 (UTC)

So in that case we need a reference relevant to 'at the time', ideally with some citations. An uncited 2011 paper behind a paywall is not useful. Mhardcastle (talk) 06:47, 15 May 2014 (UTC)

The at that time line has been in Wikipedia now for a long time, without references ever provided. Mamas' article fills that gap. Note also, all scientific journals have paywalls as you call it. 96.228.244.95 (talk) 13:41, 15 May 2014 (UTC)

The Mamas paper is a very poor source for the "at that time" claim, since it's a physics paper and not a book on the history of astronomy, and that claim isn't what was being discussed here. We are still waiting for some evidence that the "an hypothesis still defended by some" statement above, which is what is actually being discussed, is a significant minority view and not fringe. You may be surprised to learn that there are a great many journals available freely, and google books has a large number of free sources available as well. The fact that this article is in Physics Essays doesn't say much either, since it's a relatively minor journal. siafu (talk) 03:38, 16 May 2014 (UTC)

Mamas' paper is in a Physics journal, but so what ? The subject is astrophysics. Also, every astronomer in the world remembers quite well that the original dominant hypothesis regarding quasars was that it was a matter-antimatter phenomenon, and, to be sure, the hypothesis never completely went away. Mamas' paper presents convincing observational evidence for the matter-antimatter hypothesis using today's modern astronomical data. 96.228.244.95 (talk) 04:14, 16 May 2014 (UTC)

So far, all we have evidence of is the fact that this one person, who has published one paper, believes that quasars are a matter-antimatter phenomenon. That is certainly not worthy of mention in this article. siafu (talk) 04:59, 16 May 2014 (UTC)

Physics Essays is not "relatively minor", it publishes fringe papers that are not accepted anywhere else. Try to find citations to Physics Essys papers from outside of the journal, that should be informative. Basically, the journal is a vanity publication. Paradoctor (talk) 04:55, 16 May 2014 (UTC)

And to come back to the point about the paywall: you will notice that most other references to the literature in the article have links to full text on ADS, the arXiv or the journals' sites themselves. Mamas's paper is not accessible in this way. It is not a useful reference to the casual or even the professional reader, even if it were the appropriate one to cite at this point, which it is not. If you want to improve the article, find a suitable, well-cited reference from a mainstream journal with full text available from the 1960s, when this idea was taken seriously in spite of its obvious problems. Mhardcastle (talk) 07:42, 16 May 2014 (UTC)

90% of scientific articles have paywalls, including articles in Astrophysical Journal. No scientific journals offer full text articles for free. And I am glad you admit that the matter-antimatter hypothesis was taken seriously in the 1960's, and note that the hypothesis is still with us and will not go away. Many people do not believe in black holes at all, let alone that black holes cause quasars. Stephen Hawking recently himself backed off on black holes, which leaves us with matter-antimatter. 96.228.244.95 (talk) 12:28, 16 May 2014 (UTC)