State of Pulsar Theory & Observations

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It is interesting to compare pulsars to quasars. If one assumes the massive compact object at the center of a quasar is a physical object that has properties, is it similar to what creates the pulsar and magstar observations? What are the pulsar and magstar observations? What are the quasar observations? There do appear to be similarities.

The pulsar observations, the quasar observations, and magstar observations are different from what one might assume based on the cartoon pictures in text books. The explanation of these differences is included in recently published papers.

This paper was included as recommended reading at a presentation made at a pulsar conference for specialists in that field.

F. C. Michel alleges that due to more sophisticated earth and space based telescopes there is now sufficient observational evidence to make progress in pulsar theory. Michel alleges in this paper that one obstacle to advancement in pulsar astrophysics is that specific theoretical models when they are included in text books and taught fix the thinking concerning this subject. Michel alleges that observational evidence and holistic critical fundamental physical analysis of the text book models in question shows that they are fundamentally incorrect.

Michel's point is there was no rational reason to present the pulsar textbook model as the correct model. The class of pulsar model that he alleges may lead to a solution was postulated in the 1960s.

http://arxiv.org/PS_cache/astro-ph/pdf/0308/0308347v1.pdf


The State of Pulsar Theory
However, recent theoretical work is converging on a picture that closely resembles the latest HST and CHANDRA images, providing hope for the future. No less than 3 groups have recently confirmed the early Krause-Polstorff-Michel simulations showing that the fundamental plasma distribution around a rotating neutron star consists of two polar domes and an equatorial torus of trapped nonneutral plasma of opposite sign charges. Unless a lot of new physics can be added, this distribution renders the Goldreich-Julian model irrelevant (i.e., along with most of the theoretical publications over the last 33 years).

So 35 years have passed. Will the way pulsars work yield to theory alone? Will it yield to observation alone? The numbers are not on anyone’s side. I will try to suggest why theory hasn’t done it yet. One reason was the chaotic approach to the problem, everyone running in different directions. The other is, paradoxically, how a strong line of conventional wisdom keeps people from looking in different directions, which we will next examine.

Pair production

The possible role of pair production has been an interesting one, and we find it very attractive (Michel 1991b) because it could explain how charged bunches would form naturally and thereby account for the coherency of pulsar radiation. One role of pair production might be to provide ionization outside of the neutron star and thereby help “fill” the magnetosphere as imagined in the GJ model (although these authors were clear in their assumption that the magnetospheric particles all came from the surface). Although something like this should be possible (owing to the huge E* B ≠ 0 regions between the domes and the tori) STM (2001) show that the consequent filling of the domes and tori reduce this source and would turn it off. Moreover, for typical pulsars where the magnetic field at the famous light cylinder would be only of the order of a few gauss, pair production would have no chance of operating. Pair production was suggested in the first place only because the pulsar magnetic fields were so large at the surface.


Nonneutral Plasmas
Most astrophysicists or physicists are not taught nonneutral plasmas. There are relatively few sources Davidson (1990), Michel and Li (1999), Michel (1982, 1991a). Yet nonneutral plasmas are the natural plasmas to be found around strongly electrified objects like rotating neutron stars, simply because the huge electric fields tend to stratify the plasma (as in producing domes and tori) and selectively pull out plasma (from conducting surfaces) of only one sign. The fact that the plasma surrounding a rotating magnetized neutron star should be arranged in the form of domes and tori should be understood as a fundamental one which would have to be explicitly modified if one were to find a structurally different configurations (such as accelerating gaps over the polar caps) instead of simply being ignored because it doesn’t fit preconception.

Danger when theorists start looking at the same page
Theorists seem uninterested in why 35 years have passed with so little success. Not even interested enough when it can be shown that the favorite model is a cartoon model not based on real physics. The possible bad news here is that a number of other people have now become interested in how nonneutral plasmas impact our understanding of pulsars. Then everyone might have to learn this stuff!
 

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  • #2
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It is interesting to compare pulsars to quasars. If one assumes the massive compact object at the center of a quasar is a physical object that has properties, is it similar to what creates the pulsar and magstar observations?
They are both compact objects so yes there are similarities. Black holes are actually much simplier because there is no surface to attach anything to.

The pulsar observations, the quasar observations, and magstar observations are different from what one might assume based on the cartoon pictures in text books. The explanation of these differences is included in recently published papers.
A magnetar is just a pulsar with a strong magnetic field. Quasars are likely to be massive black holes. Also, I did a literature search and it seems that people agree with Michel that the basic model of pulsars that you see in intro astronomy textbooks, just doesn't work, and people are trying to figure out what does.

We basically do not understand how plasmas behave in high magnetic field situations.

OK, now what? :-) :-)

Here is a more recent paper on what we don't understand.....

http://arxiv.org/PS_cache/arxiv/pdf/0902/0902.3821v1.pdf
 
  • #3
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This is an interesting paper, because it has the signs of a crank paper, but it turns out that it isn't. What I did to see if it was a crank paper was to look at more recent papers and textbooks on pulsar magnetospheres, and I found a textbook which describes the basic textbook model with the warning that the model is likely to be very wrong with a reference to Michel's papers.
 
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Hi 2α – quant,

I believe your comment concerning Michel is correct. I am interested in Michel’s model's charge separation. I will see if I can find any review papers that summarize that model and its competition.

This is another review paper on pulsars and neutron stars.

This paper notes the observations of very recent supernova collapses found the object formed has not a pulsar. That observation could mean the collapse can create a neutron star that does not have a magnetic field, the neutron magnetic field develops later, or that the collapse formed a traditional BH. If Schild's ECO assertion is correct, (See Schild thread. Schild and others allege that they have observational evidence that shows traditional BH does not exist) traditional black holes do not form. If I understand the line of thought in Schild’s paper, all neutron stars would have a magnetic field however the magnetic field would develop later as the object cooled to arrest the collapse.


http://arxiv.org/PS_cache/astro-ph/pdf/0208/0208356v1.pdf

Pulsars and Isolated Neutron Stars

From what we know so far about radio-silent neutron stars in supernova remnants, one can conclude that such sources are quite different from radio pulsars (in particular, they do not show any activity inherent to radio pulsars). On the other hand, it is very plausible that, in fact, they are more common than radio pulsars, and the relatively small number of the discovered members of this class is due to observational selection — it is much easier to detect and identify active pulsars than these “quiet” sources observable only in the soft X-ray band.

The recent high-energy observations, however, show that the picture may not be so simple. In particular, it appears that many very young neutron stars are not active pulsars at all. The most recent example may be the central source of the 320-year-old Cassiopeia A supernova remnant (see Fig. 8.7; although at the time of writing of this article it is still not completely clear whether it is a neutron star or a black hole). Since such objects are not seen in radio, and are extremely faint in optical, they could not be observed until the onset of the X-ray astronomy era, which means that our perception of neutron star early evolution was very strongly biased in favor of much easier observable rotation-powered pulsars. Why are many (perhaps, the majority of) nascent neutron stars not active pulsars? Is it because they are indeed magnetars, whose superstrong magnetic field inhibits the pulsar activity? Or, on the contrary, their magnetic fields are so weak and/or rotation is so slow that the pulsar does not turn on? Or the pulsar activity is quenched by accretion of debris of the supernova explosion? Are the (apparently young) anomalous X-ray pulsars and soft gamma-ray repeaters indeed the magnetars or their unusual observational properties are due to quite different reasons, like a residual disk? To answer these questions, further observations, with more sensitive instruments of higher angular and energy resolution are needed.
Although the magnetic braking model is generally accepted, the observed spin-modulated emission, which gave pulsars their name, is found to account only for a small fraction of ˙E . The efficiencies, η = L/ ˙E, observed in the radio and optical bands are typically in the range ∼ 10−7 − 10−5, whereas they are about 10−4 − 10−3 and ∼ 10−2 − 10−1 at X-ray and gammaray energies, respectively. It has therefore been a long-standing question how rotation-powered pulsars lose the bulk of their rotational energy.

The fact that the energy loss of rotation-powered pulsars cannot be fully accounted for by the magneto-dipole radiation is known from the investigation of the pulsar braking index, n = 2−P ¨ P ˙P −2. Pure dipole radiation would imply a braking index n = 3, whereas the values observed so far are n = 2.515 ?0.005 for the Crab (Lyne et al. 1988), n = 2.8 ?0.2 for PSR B1509−58 (Kaspi et al. 1994), n = 2.28 ?0.02 for PSR B0540−69 (Boyd et al. 1995), and n = 1.4 0.2 for the Vela pulsar (Lyne et al. 1996). The deviation from n = 3 is usually taken as evidence that a significant fraction of the pulsar’s rotational energy is carried off by a pulsar wind, i.e., a mixture of charged particles and electromagnetic fields, which, if the conditions are appropriate, forms a pulsar-wind nebula observable at optical, radio and X-ray energies. Such pulsar-wind nebulae (often called plerions or synchrotron nebulae) are known so far only for few young and powerful (high ˙E ) pulsars and for some center-filled supernova remnants, in which a young neutron star is expected, but only emission from its plerion is detected. The mechanisms of pulsar wind generation and its interaction with the ambient medium are poorly understood.
So far, there is no consensus as to where the pulsar high-energy radiation comes from (see for example Michel 1991; Beskin et al. 1993 and discussion therein). There exist two main types of models — the polar cap models, which place the emission zone in the immediate vicinity of the neutron star’s polar caps, and the outer gap models, in which this zone is assumed to be close to the pulsar’s light cylinder9 to prevent materializing of the photons by the one-photon pair creation in the strong magnetic field, according to γ + B → e+ + e− (see Fig.8.3). The gamma ray emission in the polar cap models (Arons & Scharlemann 1979; Daugherty & Harding 1996; Sturner & Dermer 1994) forms a hollow cone centered on the magnetic pole, producing either double-peaked or single-peaked pulse profiles, depending on the observer’s line of sight.
One more set of evolutionary problems is associated with the generation and evolution of neutron star magnetic fields. Although there are no doubts that the very strong fields exist in many (if not all) neutron stars, there is no clear understanding of how they are generated. Why they are so different in different kinds of neutron stars (e.g., regular and recycled pulsars), what is their geometry, and do they decay during the neutron star life time? It should be mentioned that the direct measurements of the magnetic field have been possible only for neutron stars in binaries. What is called the “magnetic field” in, e.g., radio pulsars, is only an order-of-magnitude model-dependent estimate. Direct measurements of magnetic fields in isolated neutron stars, e.g. with the aid of spectral lines formed in their photospheres or from X-ray polarimetry, is one of very important goals for future observations.
http://www.chjaa.org/2008/Italy2008/P24_250_kundt_213-218.pdf


Definition and Properties of the Magnetars


Magnetars have been defined by Duncan and Thompson some 15 years ago, as spinning, compact X-ray sources - probably neutron stars - which are powered by the slow decay of their strong magnetic field, of strength 10^15 G near the surface, cf. (Duncan & Thompson 1992; Thompson & Duncan 1996). They are now thought to comprise the anomalous X-ray pulsars (AXPs), soft gamma-ray repeaters (SGRs), recurrent radio transients (RRATs), or ‘stammerers’, or ‘burpers’, and the ‘dim isolated neutron stars’ (DINSs), i.e. a large, fairly well defined subclass of all neutron stars, which has the following properties (Mereghetti et al. 2002):

1) They are isolated neutron stars, with spin periods P between 5 s and 12 s, and similar glitch behaviour to other neutron-star sources, which correlates with their X-ray bursting.
2) They are soft X-ray sources, hotter than pulsars of the same spindown age by a factor of >∼3 whose emission can be explained as due to magnetospheric interactionswith the throttling CSMand/ormild accretion - yet mostly without pulsed coherent radio emission. A radio-loud exception has been detected by Camilo et al. (2006).

3) Their spindown is rapid, _ = 104±1 yr, despite ongoing accretion.
4) Their estimated number in the Galaxy is large, comparable to the number of pulsars. Due to their short spindown times (of order 104 yr, instead of the 106.4 yr at which pulsars die, see next section), their visible number in the sky is reduced by a factor of order 10−2.4 compared with ordinary pulsars.
5) They may well derive their power (<∼ 1036 erg s−1, for d >∼ 10 pc) from accretion, whose implied (small) spinup is overcompensated by magnetospheric braking.
6) They are often (some 50%) found near the center of a pulsar nebula (Gotthelf et al. 2000).

Above definition (of the magnetars) meets with insurmountable difficulties: Surface dipole field strengths of >10^15 G imply internal field strengths of <∼ 1017 G, too high to be anchored by the core of a neutron star; the fields would decay on a dynamical timescale. Secondly, no convincing formation mode for such strong stellar magnetic dipoles is known. The third - and perhaps least indirect - reason against the existence of magnetically powered compact stars is the fact that the two SGRs 1900+14 and 1806–20 both experienced upward jumps in ˙P during glitches (which correlated with flares: Marsden et al. (1999), Rea et al. (2006)): A rise in ˙P corresponds to an increase of the braking torque, which would be energetically forbidden if powered by the magnetic moment.
 
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This paper notes the observations of very recent supernova collapses found the object formed has not a pulsar. That observation could mean the collapse can create a neutron star that does not have a magnetic field, the neutron magnetic field develops later, or that the collapse formed a traditional BH.
This is another thing is very poorly understood. We don't really have any idea what the relationship is between a progenitor star and what it leaves behind. It may be that magnetic fields and plasma play a critical role in supernova, or not.

One thing that is helping things a lot is that we can throw more computer cycles at the problem and see what's going on.

If Schild's ECO assertion is correct, (See Schild thread. Schild and others allege that they have observational evidence that shows traditional BH does not exist) traditional black holes do not form. If I understand the line of thought in Schild’s paper, all neutron stars would have a magnetic field however the magnetic field would develop later as the object cooled to arrest the collapse.
The people that know GR think that Schild and Mitra are cranks, and based on what I know about plasma gas dynamics, I tend to agree with the people that think they are cranks.

Also it's very hard for a compact rotating object not to have a magnetic field, and once you have a magnetic field all sorts of wild and crazy things start to happen. The think about GR and black holes, is that if you have enough gravity, then the physics actually becomes a lot simpler because gravity overwhelms everything. Astrophysically speaking, black holes are a lot, lot more simple than neutron stars.

One other thing is that there are a lot of professional cranks out there. Every theoretician has this wacky idea that they have about the universe, but the hard part is to keep the "inner crank" under control. (I have some *really* wacky ideas. What keeps me looking sane is that I realize how wacky my wacky ideas are.)
 
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This is another thing is very poorly understood. We don't really have any idea what the relationship is between a progenitor star and what it leaves behind. It may be that magnetic fields and plasma play a critical role in supernova, or not.

The people that know GR think that Schild and Mitra are cranks, and based on what I know about plasma gas dynamics, I tend to agree with the people that think they are cranks.

Also it's very hard for a compact rotating object not to have a magnetic field, and once you have a magnetic field all sorts of wild and crazy things start to happen. The think about GR and black holes, is that if you have enough gravity, then the physics actually becomes a lot simpler because gravity overwhelms everything. Astrophysically speaking, black holes are a lot, lot more simple than neutron stars.

One other thing is that there are a lot of professional cranks out there. Every theoretician has this wacky idea that they have about the universe, but the hard part is to keep the "inner crank" under control. (I have some *really* wacky ideas. What keeps me looking sane is that I realize how wacky my wacky ideas are.)
Name calling seems to me to be irrational. There is no logic associate with it.

Schild, Stanley Robertson and Darryl Leiter are quasar specialists that have multiple papers published with observational evidence that supports their assertion that there is a strong magnetic field associated with the massive objects that are believed to be in the center of most galaxies.

http://iopscience.iop.org/1538-3881/132/1/420

http://www.springerlink.com/content/l567753822878251/

http://iopscience.iop.org/1538-4357/596/2/L203/pdf/17685.web.pdf

I do not understand the emotion that appears to be attached to this subject and I do not know what to say in response to it. The objective is to solve a scientific problem. The observations do not support the classical BH model.

As noted above there is no explanation as to what is creating the massive magnetic field in neutron stars to create the pulsar and magnetar observations yet for some reason people are convinced that it is not possible that a more massive object could have a massive magnetic field. Quite obviously if charge separates in the massive object it will not collapse. The ratio of gravitational force to electrostatic force is roughly 10^36.

What happens in the very, very, massive object requires a complete understanding of extreme physics. The simplistic calculations that were done at the turn of the century are not applicable and appear to be some sort of weird barrier to thinking about the real world observations. The pulsar and magnetar observations are indications of what to expect at those very extreme conditions. There is a equal portion of energy in the allowed states of the massive object that arrests the collapse. In addition it is observed that the pulsar and magnetar evolve. They do not remain the same. The quasar's massive object also changes over time based on observations. That is what one would expect if the very, very, massive object is a physical object.
 
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  • #7
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Name calling seems to me to be irrational. There is no logic associate with it.
It's not. Name calling based on fact is not irrational. There *is* logic associated with the name calling.

Schild, Stanley Robertson and Darryl Leiter are quasar specialists that have multiple papers published with observational evidence that supports their assertion that there is a strong magnetic field associated with the massive objects that are believed to be in the center of most galaxies.
Which doesn't surprise anyone. Everyone knows that there are strong magnetic fields associated with massive objects in the center of quasars, and Kip Throne showed a few years back, how you can model strong magnetic fields associated with black holes. Having strong magnetic fields gives you no problems with black holes. Now showing that you have a strong magentic field that isn't aligned the axis of rotation would be interesting.......

Also the fact that they have multiple papers published means that they aren't totally cranks, but some of the papers published in ApJ are pretty crankish. The good/bad thing about astrophysics is that it's not hard to publish a paper, and people will tend to publish even if they think you are nuts. Also, there are distinguished professors that have ideas that everyone else thinks are nuts. Most of the time it turns out they are nuts. Sometimes they aren't.

Science is not about resumes and awards. I know of Nobel prize winners in physics that have some really, really nutty ideas. I know of at least one Nobel prize winner that believes left and right, up and down, that black holes do not exist. I think he is wrong and nutty about this. Also crankishness and nuttiness goes with the territory. I have two or three nutty ideas of my own.

But in any case, it's really important to understand why people think that Schild is nuts and Michel is not. There are reasons. What it boils down to is that when Michel shows his equations, people look at them at say. Yes, I see how this works. When Schild and Mitra shows his equations, people look at the equations and say "no it doesn't work that way."

I do not understand the emotion that appears to be attached to this subject and I do not know what to say in response to it. The objective is to solve a scientific problem. The observations do not support the classical BH model.
So they claim. Most people in the field strongly disagree. People are human and if someone doesn't appear to be listening to you when you state an obvious fact, the human tendency is to start talking louder.

As noted above there is no explanation as to what is creating the massive magnetic field in neutron stars to create the pulsar and magnetar observations yet for some reason people are convinced that it is not possible that a more massive object could have a massive magnetic field.
Ummmm... There is a quite good explanation of what causes magnetic fields in compact objects. You have a charged gas. Things are rotating quite rapidly, this creates a magnetic field. Now figuring at there is a magnetic field and the rough strength of the magnetic field is pretty easy. Figuring out the shape of the magnetic field is extremely, extremely difficult.

Michel's papers have nothing to do with Schild, because Michel is arguing that the details of how the field is created is wrong, but with massive compact objects, it's hard not to have a magnetic field.

Quite obviously if charge separates in the massive object it will not collapse. The ratio of gravitational force to electrostatic force is roughly 10^36.
Incorrect. The thing about electromagnetic fields is that the are both attractive and repulsive so at long distances the charges cancel out. Gravity is only attractive, so it wins. Any time you have a strong electromagnetic field it attracts the opposite charge so that it tends to cancel out. Note also that for these objects we are talking about magnetic fields and not static fields. Static fields don't last very long in astrophysics because you can't get large charge separations at large distances. Magentic fields last a lot longer because if you objects don't go in the direction of the charge.

What happens in the very, very, massive object requires a complete understanding of extreme physics.
It doesn't. What you can do is to set limits. X is unknown, how much can X change things. To get an example, I don't know whether it will rain or shine tomorrow, but I do know that it won't be -100 celsius or +350 celsius. I don't know whether I will need a sweater or a rain coat, but I do know that I won't need oxygen tanks or kelvar suits. Then you ask yourself, well. if I don't know what the weather is tomorrow, how do I know that I won't need an oxygen tank, and it turns out that there are some simple equations that illustrate why you don't.

We don't understand the details of nuclear physics at high densities. So what you do is to say, OK we don't know, so lets put in a factor in our equations that describes what we don't know. It turns out that for no set of equations of state can you avoid black holes, unless you are willing to destroy special relativity.

You don't understand everything. You'll never understand everything. But you don't have to understand everything to understand something.

The simplistic calculations that were done at the turn of the century are not applicable and appear to be some sort of weird barrier to thinking about the real world observations.
Yes they are. You want simple calculations if they work.

[QUOTE[The pulsar and magnetar observations are indications of what to expect at those very extreme conditions. There is a equal portion of energy in the allowed states of the massive object that arrests the collapse.[/QUOTE]

Which falls apart once you have enough mass. The idea is pretty simple. You can't push things faster than the speed of light. Once something goes close to the speed of light, and you push on it, there isn't enough time for the material to push back, and so you lose pressure support. Electrons are light so it doesn't take much mass for them to start moving at the speed of light. Once they start moving near the speed of light, they lose pressure, and things combine to form neutrons. Once neutrons start moving near the speed of light, they lose pressure, and things collapse. If you add enough mass, anything moves near the speed of light, and you lose pressure.

Here is another way of thinking about it. As things move close to the speed of light, they start acting like light, and you can't build a floor out of light.

In addition it is observed that the pulsar and magnetar evolve. They do not remain the same. The quasar's massive object also changes over time based on observations. That is what one would expect if the very, very, massive object is a physical object.
Read....

http://en.wikipedia.org/wiki/Membrane_paradigm

What Kip Throne has done is to take the equations of GR and they show that black holes can be thought of as physical objects even though they aren't. It turns out that as a black hole forms, it starts behaving as if it has a surface at the event horizon.

Also people do change their minds. There was one physicist that I know of that wrote a major paper on the anthropic principle which I thought was totally insane when I first read it, but after some time I've changed my mind. But right now there are some really good reasons why people think that Schild and Mitra have their physics wrong, and it's a good idea to keep the discussion in physics rather than sociology.

You seem to be pretty curious, and if you are at least interested in knowing in detail why I and pretty much everyone else thinks that Schild and Mitra are nuts, then I'll be happy to explain. You might end up thinking that I'm crazy and that's fine, but one point that I really want to make is that I'm not bashing Schild and Mitra because they are "different". I'm bashing them because I think they are wrong. Michel is different, but what he says makes sense to me. If you want to know why I think that Schild and Mitra are wrong, go ahead and ask.
 
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One big problem here is that ultimately the only way of resolving this sorts of questions is to "do the math." People come up with all sorts of rough rules intended to figure out what is going on without doing the math, but those rules tend to break down.

I don't think I can (or should) be able to convince you that Schild and Mitra are wrong without going into the details of the the math. What I think I can convince you of is that there are good reasons to think that they are very wrong, and people aren't negative about them because they are different or original.

We are talking about people that deal with nutty and crazy ideas like dark matter and dark energy. If you can argue that black holes don't exist and have convincing reasons behind them, that's great. The problem is that Schild and Mitra have arguments that most people including myself think are pretty fatally flawed.

Also one thing about physics is that people can be total cranks in one field and then be totally brilliant in another. It has to do with the fact that you need to be a little crazy to come up with original ideas. Also, sometimes it's just a matter of luck. You come up with this cool idea, except that it turns out that the universe just doesn't work that way. Bummer.

The Nobel prize winner that I knew of that was convinced up and down that black holes didn't exist, wasn't an astrophysicist, and was totally incredibly brilliant in his field. It's just that when the topic of black holes came up, people were quick to change the topic. So someone that is an expert in quasar observations could know absolutely nothing about the theoretical physics of compact objects.

The other thing that makes the internet useful is that you don't know who you are talking do. I might have credentials that are a hundred times more impressive than someone elses, or not..... You don't know and I think it's a good thing you don't know.
 
  • #9
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My general reaction is that all Schild and Mitra have done is to rediscover the membrane paradigm which Kip Thorne figured out in 1978. They are going through exactly the same equations and the same arguments, but I think they are just interpreting them incorrectly.

Kip Thorne was able to show that from a distant observer, a black hole looks exactly like what Schild is describing as a MECO. From an infinite observation, you never quite see anything falling into the black hole because as things get closer to the black hole, the light rays get stretched out, and so it appears as if nothing falls into the black hole, and if you do your equations using the coordinate system of a distant observer, you get as far as I can tell the same equations as Schild and Mitra do.

The thing about this is that this is an "optical illusion". The matter does fall into the black hole in finite time, it's just from the point of view of someone on the outside the information that matter falling into the black hole takes an infinite time to enter the black hole.

Kip Throne's papers are really, really important because, they gave "mere mortals" like myself a way of thinking about black holes without being math supergeniuses. You think of a black hole as a membrane that has a certain charge. Once you spin that charged membrane, you get a magnetic field.

There is a great non-technical article about the membrane paradigm in "The membrane paradigm for black holes". Scientific American 4/1988.

The thing that I find curious is that Schild and friends don't cite any papers about the membrane paradigm even though it's pretty standard in astrophysical research.
 
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Also, reading over Schild's papers, I think there is some useful content in there, and if I were a peer reviewer, I would have argued that they be published. His ideas on black holes are I think nutty, but he wrote the paper carefully enough so that you don't have to accept his nutty ideas in order to agree with the point he is making in the paper.

The other thing is that we have to be careful about what Schild thinks. It's not at all obvious from his peer-reviewed papers that he has written that he thinks black holes don't exist. He might not, but you don't have to accept any of his ideas on black holes for that paper to be useful, and since it's not clear from his papers that he thinks black holes don't exist, I don't want to have him screaming at me if it turns out that this isn't his view.

Also it's really important to keep the ideas separate from the person or the topic under discussion.

The other thing is that my thinking on this is very highly influenced by the fact that I do computer simulations of supernovas. One thing that you can do is to run the simulation under general relativity and then let things fall into the neutron star, and then watch a black hole form.

The thing is that you never actually see the black hole form. What happens is that you get something that looks like a MECO. But it's not. What's happen is that you've set up the formula so that you never do see the black hole form, because you are researching supernova and not black holes.

What happens is that as gravity increases, you set up the simulation so that part of the simulation runs slower and slower. When it becomes a black hole, the speed of the simulation is zero, and so you (intentionally) never reach a point where you see the black hole form. The outer parts of the simulation runs at "normal" speed, but the inner parts of the simulation run at "slow motion" and at the point where the black hole forms, it's "zero motion". It turns out that if you do this carefully, you end up with exactly the right results for everything outside of the black hole (and the stuff inside you don't care about).

But the important this is that I've set up the equations to do this intentionally (see Van Riper 1979), and Kip Throne also sets of the equations to do this intentionally. What I think Schild is doing is that he is also setting up his equations to give the same result, but he may be doing this unintentionally and totally messing up the interpretation (or maybe not).

So what this means is that Schild has a publishable paper because he gets the right results from the wrong model. That happens a lot. Newtonian mechanics is strictly speaking "wrong" but you end up with the right results.
 
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It's not. Name calling based on fact is not irrational. There *is* logic associated with the name calling.

Which doesn't surprise anyone. Everyone knows that there are strong magnetic fields associated with massive objects in the center of quasars, and Kip Throne showed a few years back, how you can model strong magnetic fields associated with black holes. Having strong magnetic fields gives you no problems with black holes. Now showing that you have a strong magentic field that isn't aligned the axis of rotation would be interesting.......

Also the fact that they have multiple papers published means that they aren't totally cranks, but some of the papers published in ApJ are pretty crankish. The good/bad thing about astrophysics is that it's not hard to publish a paper, and people will tend to publish even if they think you are nuts. Also, there are distinguished professors that have ideas that everyone else thinks are nuts. Most of the time it turns out they are nuts. Sometimes they aren't.

But in any case, it's really important to understand why people think that Schild is nuts and Michel is not. There are reasons. What it boils down to is that when Michel shows his equations, people look at them at say. Yes, I see how this works. When Schild and Mitra shows his equations, people look at the equations and say "no it doesn't work that way."

So they claim. Most people in the field strongly disagree. People are human and if someone doesn't appear to be listening to you when you state an obvious fact, the human tendency is to start talking louder.

Michel's papers have nothing to do with Schild, because Michel is arguing that the details of how the field is created is wrong, but with massive compact objects, it's hard not to have a magnetic field.

We don't understand the details of nuclear physics at high densities. So what you do is to say, OK we don't know, so lets put in a factor in our equations that describes what we don't know. It turns out that for no set of equations of state can you avoid black holes, unless you are willing to destroy special relativity.

You don't understand everything. You'll never understand everything. But you don't have to understand everything to understand something.

Yes they are. You want simple calculations if they work.

Which falls apart once you have enough mass. The idea is pretty simple. You can't push things faster than the speed of light. Once something goes close to the speed of light, and you push on it, there isn't enough time for the material to push back, and so you lose pressure support. Electrons are light so it doesn't take much mass for them to start moving at the speed of light. Once they start moving near the speed of light, they lose pressure, and things combine to form neutrons. Once neutrons start moving near the speed of light, they lose pressure, and things collapse. If you add enough mass, anything moves near the speed of light, and you lose pressure.
Schild has found evidence that there is an extremely strong magnetic field in a region of the quasar (in the core above the poles of the massive object) where an accretion disk cannot create a magnetic field (strong or weak.)

As I noted the forbidden line emission in quasars requires the excitation of a very strong vacuum. The accretion disk is in a region surrounded by gas. The accretion disk's magnetic field therefore cannot excite a very strong vacuum. The region of the quasar above its poles has a very strong vacuum. Schild's mechanism has a massive magnetic field that is attached or is intrinsically part of the massive object, just like what we observe with a pulsar or a magnetar. The quasar's core rotates which causes the massive magnetic field to also rotate.

Schild is not stating that an accretion disc does not get hot and likely does have a weak magnetic field associated with it. Schild's observations support the assertion that quasars can have up to two magnetic fields generated by different mechanism in different regions.

Quasar radiate that do not have accretion disks. How is that possible if the quasar core is a classical BH?

10% of quasars are naked quasars that do not have broad line region emissions. The BLR are thought to have been caused by the accretion disk (i.e. The accretion disc gets hot and rotates rapidly around the massive object which explains the BLR emissions.). The naked quasar's massive objects appear to not have accretion disks as they do not exhibit BLR emissions, yet they radiate. An extremely strong magnetic field anchored to a massive object will radiate. The observational evidence supports the assertion that the massive object has an intrinsic massive magnetic field.

You say extreme physics is not relevant then you precede to tell me what happens when a massive object collapses in a very confident tone. You state that the object becomes a neutron star. Really and you know that because you read it in a text book. Is there observation evidence to support that assertion? This is not religion where the words in the books are dogma, inspired with deep meaning. The fact that you use the word "crank" makes it appear that you have decided without knowledge of the quasars observations.

Mathematical analysis is only as good as the model and the model's assumptions. Physical observations prove or disprove the validity of the assumptions and the model. That is the scientific process.

The observations concerning Magnetar and pulsars are relevant as the collapsing massive object produces a massive magnetic field. How? Or looking at the physical observations from another perspective why? The massive object produces a massive magnetic field to arrest the collapse. (See above for the observation that newly formed neutron stars are not pulsars. The object's magnetic field strengthens as the object cools.)

Mitra notes that a massive magnetic field produces electron positron pairs in space. The electron positron pairs recombine producing gamma radiation. The gamma radiation arrests the collapse of the object.

Observations indicate the massive object at the center of galaxies does not exceed 10^10 solar masses for any AGN or quasar. Why? Or asking the question another how can the massive object stop the infall. (The point is mass continues to infall in to the massive object. Dark matter if it exists make the problem more difficult to explain.) There are quasars at Z=5 whose cores are a billion solar masses. Galaxies continue (from the time of z=5 to the present) to merge, gas continues to infall in the quasars. Why do the quasars not increase in mass?

The quasars pulsate with an increasing magnitude pulse (I will provide a link to Hawkins' papers and will explain his observations). The massive object in the center of the galaxies or in quasars is not stable. It changes overtime based on observations.
 
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I must be missing something. I see 42 published papers referenced in this paper that provides detail observational data to support the assertion that the massive object at the center of quasars and AGN has an intrinsic magnetic field. That mechanism is called a MECO. The authors are quasar specialists and senior astronomers/astrophysicists. The MECO mechanism explains other quasar mysterious such as the forbidden band emissions or why 10% of the observed quasars can radiate yet appear to not have an accretion disk.

I must be missing something. I do not see any papers disputing the author’s findings. The authors explain how the massive object arrests its collapse through Compton photon pressure where the photons are created by electron positron pair recombination. (The electron positron pairs are created by the massive magnetic field.)

There appears to be other observation evidence such as the pulsars and magnetar observations that supports the assertion that massive objects develop massive intrinsic magnetic fields. (I would assume also to arrest the collapse of the massive object.)

This seems to be an open and shut case.

Comments:
Other quasar observations such as the forbidden region emission supports the authors assertion that quasars can have up to two magnetic fields. For example, the forbidden band emission requires the excitation of ions in a very hard vacuum. There was no explanation as to how ions could be excited by the accretion disk’s magnetic field as that region is surround by dust and gas as evidence by the absorption lines. The region above the poles of the quasar is exited by the MECO’s magnetic field. That region is separated from the accretion disk and has extremely rarefied gas.

http://iopscience.iop.org/1538-3881/135/3/947/aj_135_3_947.text.html



Direct Microlensing-Reverberation Observations of the Intrinsic Magnetic Structure of Active Galactic Nuclei in Different Spectral States: A Tale of Two Quasars


We show how direct microlensing-reverberation analysis performed on two well-known quasars (Q2237, the Einstein Cross, and Q0957, the Twin) can be used to observe the inner structure of two quasars which are in significantly different spectral states. These observations allow us to measure the detailed internal structure of Q2237 in a radio-quiet high-soft state, and compare it to Q0957 in a radio-loud low-hard state. When taken together we find that the observed differences in the spectral states of these two quasars can be understood as being due to the location of the inner radii of their accretion disks relative to the co-rotation radii of the magnetospheric eternally collapsing objects (MECO) in the centers of these quasars. The radiating structures observed in these quasars are associated with standard accretion disks and outer outflow structures, where the latter are the major source of UV-optical continuum radiation. While the observed inner accretion disk structure of the radio-quiet quasar Q2237 is consistent with either a MECO or a black hole, the observed inner structure of the radio-loud quasar Q0957 can only be explained by the action of the intrinsic magnetic propeller of a MECO with its accretion disk. Hence a simple and unified answer to the long-standing question: "Why are some quasars radio loud?" is found if the central objects of quasars are MECO, with radio-loud and radio-quiet spectral states similar to the case of galactic black hole candidates.

In Appendices 1-10 of Schild et al. (2005) it was shown that, by using the Einstein-Maxwell equations and quantum electrodynamics in the context of general relativistic plasma astrophysics, it was possible to virtually stop and maintain a slow (many Hubble times!), steady collapse of a compact physical plasma object outside of its Schwarzschild radius.

The non-gravitational force was Compton photon pressure generated by synchrotron radiation from an intrinsic equipartition magnetic dipole field contained within the compact object. The rate of collapse is controlled by radiation at the local Eddington limit, but from a highly redshifted surface.

In Appendices 9 and 10 of Schild et al. (2005), it was shown that general relativistic surface drift currents within a pair plasma at the MECO surface can generate the required magnetic fields. In particular, it was shown in Appendix 9 that the equatorial poloidal magnetic field associated with a locally Eddington limited secular rate of collapse of the exterior surface was shown to be strong enough to spontaneously create bound electron-positron pairs in the surface plasma of the MECO. In the context of the MECO highly redshifted Eddington limited balance, the action of this QED process was shown to be sufficient to stabilize the collapse rate of the MECO surface.

For the case of hot collapsing radiating matter associated with the MECO, the corresponding exterior solution to the Einstein equation has been shown to be described by the time-dependent Vaidya metric where no coordinate transformation between MECO Vaidya metric and the black hole Kerr-Schild metric exists. Since the highly redshifted MECO Vaidya metric solutions preserve the SPOE they do not have event horizons, and in addition they exhibit a distantly observed slowly rotating intrinsic magnetic dipole moment which interacts with a surrounding accretion disk. Hence the MECO magnetic moments will have observable effects which distinguish them from black holes if such MECOs exist at the centers of GBHCs and AGNs.
 
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Schild has found evidence that there is an extremely strong magnetic field in a region of the quasar (in the core above the poles of the massive object) where an accretion disk cannot create a magnetic field (strong or weak.)
It's not from the accretion disk. It's from the black hole.

Schild's mechanism has a massive magnetic field that is attached or is intrinsically part of the massive object, just like what we observe with a pulsar or a magnetar. The quasar's core rotates which causes the massive magnetic field to also rotate.
Which as far as I can tell is exactly the dynamo mechanism that Kip Throne proposed for black holes in 1978. What Throne was able to show was that general relativity causes a black hole to behave as if it were a conductivity sphere. Once you rotate the sphere you get a dynamo effect that can cause the black hole to have a strong magnetic field.

Now it could be that Schild thinks that there is something wrong with that mechanism, but since he hasn't referenced it in any paper that I've seen, I can't tell.

Schild's observations support the assertion that quasars can have up to two magnetic fields generated by different mechanism in different regions.
Which is not inconsistent with a black hole.

The observational evidence supports the assertion that the massive object has an intrinsic massive magnetic field.
Yes, and you only have a problem if you assert that black holes can't have intrinsic magnetic fields. They can.

Really and you know that because you read it in a text book.
No. It's because no one has detected any pulsars more than 1.7 solar masses, and all the known compact objects greater than 3 solar masses don't show any bursting behavior.

You can have a black hole with a strong magnetic field, but because the field is disconnected with anything that is happening inside the black hole, you end don't end up with sudden bursts or pulsations which you do with pulsars.

Now if you show me a 4 solar mass pulsar, that changes everything. What you have shown me is a ultra massive object with a strong magnetic field. Unless you can show that you can't get a strong magnetic field from a black hole, that's irrelevent.

The massive object produces a massive magnetic field to arrest the collapse. (See above for the observation that newly formed neutron stars are not pulsars. The object's magnetic field strengthens as the object cools.)
OK. this is a different mechanism from the anything that you've described in any papers that you have cited. I can't comment on this since I haven't seen the math for this. If you are trying to argue that a spinning object produces a magnetic field that produces an explosion (i.e. a supernova), then this is something that people I know have been working on, but it's a different mechanism than the one that any paper you've cited has presented.

Mitra notes that a massive magnetic field produces electron positron pairs in space. The electron positron pairs recombine producing gamma radiation. The gamma radiation arrests the collapse of the object.
Again, this is a different mechanism than any thing that you've presented. I can't comment on how this will or won't work because I haven't seen the math. One problem that I see with this mechanism is that in collapsing neutron stars, the main energy losses are from neutrinos, and that's what kills pressure support.

Observations indicate the massive object at the center of galaxies does not exceed 10^10 solar masses for any AGN or quasar. Why? Or asking the question another how can the massive object stop the infall.
It doesn't, you have a black hole that keeps gobbling stuff up until it runs out of gas to gobble up.
 
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I must be missing something. I see 42 published papers referenced in this paper that provides detail observational data to support the assertion that the massive object at the center of quasars and AGN has an intrinsic magnetic field.
Yes. What you are missing is that somehow you seem to have this notion that black holes can't have intrinsic magnetic fields when in fact Kip Thorne has shown that they can.

https://www.amazon.com/dp/0300037708/?tag=pfamazon01-20&tag=pfamazon01-20

Now the magnetic field around black holes are quite different from the magnetic field around neutron stars, which nicely explains why 1.2 solar mass compact objects behave differently than 8 solar mass compact objects.

That mechanism is called a MECO.
Otherwise known as a black hole. Black holes can have intrinsic magnetic fields. The reason that Schild is able to publish even though he has some weird ideas about black holes is that when anyone reads the word MECO, they just replace it with "black hole."

I must be missing something. I do not see any papers disputing the author’s findings.
You don't see any papers disputing the author's findings that there is a massive object in the middle of a quasar with a massive magnetic field that producing the various observations that we see. It's just that pretty much everyone thinks that it's a black hole. Now as far as the idea that black holes don't exist, you'll note that in none of the published papers do they very loudly make the claim that what is producing the radiation is not a black hole.

One point here. It's OK to be nutty. Sometimes cranks and nutcases turn out to be right (continental drift for example). It's not OK to argue that the scientific consensus supports you when it doesn't. If you think that everyone is wrong, that's fine. If tomorrow, someone points out a 4 solar mass pulsar, then at that point Mitra is a genius. If not, then not.

The authors explain how the massive object arrests its collapse through Compton photon pressure where the photons are created by electron positron pair recombination. (The electron positron pairs are created by the massive magnetic field.)
Not in any of the papers you've cited. If you have some other papers that describe this mechanism, I'd like to see them.

The problem that you have is that the main energy losses are neutrino losses. You can increase the photon pressure all you want, it's not going to change anything. Also if you increase pressure due to photons, then you decrease magnetic pressure.

The other thing is that if you increase the mass of the collapsing object, then eventually gravity wins.

There appears to be other observation evidence such as the pulsars and magnetar observations that supports the assertion that massive objects develop massive intrinsic magnetic fields.
Absolutely!!!

(I would assume also to arrest the collapse of the massive object.)
Maybe. I actually know some colleagues of mine that are working to see if you can have massive magnetic fields stop the collapse of a massive star. and produce a supernova. I also happen to be friends with the guy that invented the idea of the magnetar.

This seems to be an open and shut case.
It's not. One big problem with magnetic field is that magnetism doesn't push in the direction of the magnetic field. This means that you could have a huge magnetic field, but it just causes the object to spin faster and faster. The other problem is that if you have enough mass, gravity wins. Magnetism is energy and if you require a strong magnetic field to halt the collapse, E=mc^2 and that magnetic field creates a gravitational field that causes the collapse to accelerate.

It's *really* hard to do these calculations because there are so many thing going on. One problem that we have is that if you put all of the physics into a computer, and just let it run, what ends to happen is that everything ends up collapsing into a black hole, even stuff that we know doesn't collapse into a black hole. So our understanding of collapsing objects is pretty busted.

The reason we think that black holes exist is that we see things that look, smell, and act like black holes. If we didn't, then it's possible that we've messed up something basic and stars just don't turn into black holes, but we do. It just so happens that 1.2 solar mass compact objects behave very, very differently than 8 solar mass objects, and the prevailing explanation is that one is a neutron star and the other is a black hole. There are no 8 solar mass pulsars that we know of.
 
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You can go to Kip Thorne's publications page

http://www.its.caltech.edu/~kip/scripts/publications.html

The main paper is here

D. Macdonald and K.S. Thorne, "Black-Hole Electrodynamics: An Absolute-Space/Universal-Time Formulation," Monthly Notices of the Royal Astronomical Society, 198, 345-382 (1982).

http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1982MNRAS.198..345M

Yes. Quasars and AGN have very strong magnetic fields. The prevailing view is that it comes from the black hole that's in the middle of them. You can jump up and down and scream, quasars and AGN have strong magnetic fields in them, and the general response to that is "yes we know that."

Also Kip Thorne wrote an excellent article about this mechanism in Scientific American in 1988 back in the days when SciAm was a real science magazine.

Now if you have any good reasons for thinking that Kip Thorne is wrong and that his mechanism just will not work, then that would be an interesting topic for discussion.
 
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One other thing is that I don't think that you can stop a collapse by magnetic pair-production. The problem is that if you have enough energy to produce electron-positron pairs, you have enough energy to produce neutrino/anti-neutrino pairs.

Also pair-production tends to destabilize a star rather than to destabilize it...

http://en.wikipedia.org/wiki/Pair-instability_supernova

There's all sorts of interesting, poorly understand physics going on here. If you just go with the theory, then it's not obvious that black holes can form, but the idea that black holes exists comes from things like Cygnus X-1 which looks, smells, and tastes like a black hole. If you can come up with smoking gun evidence that high mass compact stars are not black holes that would be interesting, but the fact that AGN's and quasars have strong magnetic fields is not this sort of evidence.
 
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The basic thing that I just don't understand which someone needs to explain to me is why Schild seems to think that black holes can't have strong intrinsic magnetic fields. I can point to Kip Thorne's papers in which he describes how black holes can generate huge magnetic fields.

If you can point to some argument that goes through Thorne's mechanism and shows that he is simply wrong (i.e. something along the lines of what Michel did with the GJ model), and that black holes simply cannot generate massive magnetic fields, then that changes things. Until then, it's really, really hard for me (or most people in the field) to take Schild's assertions seriously.

When I look at the papers you have referenced, it looks to me that the MECO's he is describing are in fact black holes, and someone needs to explain to me why the object he references in his papers aren't black holes.
 
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Here is a review paper on black hole magnetospheres...

http://arxiv.org/pdf/0909.2580

If you go www.arxiv.org and type in "black hole" and "magnetic field" you get 842 hits.

What it boils down to is that Schild seems to think that the fact that AGN and quasars have very strong magnetic fields some how disproves the idea that they are powered by black holes. What I don't understand is why Schild seems to think that black holes can't have strong intrinsic magnetic fields when no one else seems to have any problem with the idea.

Before we go any further, I'd really like to understand why he seems to think that. This isn't a rhetorical statement. It's really like to understand what he is asserting.
 
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It's not from the accretion disk. It's from the black hole.



Observations indicate the massive object at the center of galaxies does not exceed 10^10 solar masses for any AGN or quasar. Why? Or asking the question another how can the massive object stop the infall.
It doesn't, you have a black hole that keeps gobbling stuff up until it runs out of gas to gobble up.
There is something that limits black hole growth to 10^10 solar masses. As noted in this quasar survey summary the quasar massive object's mass at z approx. 6 is at most a few 10^10 solar masses. There are no larger super massive objects at any redshift than a few 10^10 solar masses.

Note if dark matter exists the problem becomes more difficult to explain as the black holes should overtime gain mass due to dark matter. They do not which appears to indicate dark matter does not exist and the massive object has a property that it stop mass gain and/or lose mass.

The are the peculiar fountain of youth stars that orbit the Milky Way's massive object and curiously also orbit Andromeda's massive object. They are called the fountain of youth stars as they have very short lifetimes do to there size and high temperatures.

Somewhat puzzling is how does one explain the Milky Way's center's massive object's 3.6 x 10^6 solar masses (BH were 10^10 solar masses at z=6) and Andromeda's 30 x 10^6 solar masses. The Milky Way is a relatively large galaxy.

There is also the interesting hypervelocity stars that are also massive hot short lived stars that have speeds in excess of the galaxy's escape velocity.

These hot short lived stars appear to be special stars that have a much longer lifetime than other similar hot stars in the galaxy.

http://articles.adsabs.harvard.edu//full/2006MmSAI..77..635F/0000635.000.html

Evolution of high-redshift quasars by Xiaohui Fan

The black hole mass estimates of the z approx. 6 SDSS (survey data) quasars ranging from several times 10^ 8 solar masses to several times 10^10 solar masses. Assuming continuous Eddington accretion from a seed black hole of 100 solar masses, the formation redshift for seed black holes must be at z > 10. Even with continuous accretion, black holes in the most luminous quasars barely had enough time growing. While there are various ways of accreting faster than Eddington, the fact that the highest redshift quasars sit right at the threshold of the reionization epoch simply indicate that the initial growth of those BHs have to be very efficient and very early on. Figure 6 shows the black hole mass distributions at z > 3 from the SDSS samples using virial relations. One intriguing feature that we noticed is the apparent lack of quasars with BH masses larger than a few times 10^10 solar masses, at all redshift.
 
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Can we focus on mystery at a time :-) :-) :-)

One problem with astrophysics is that there are so many things that we either don't understand or understand poorly that it's hard really have a discussion if we talk about all of them. Now it might be that a lot of the questions are connected in some way, or not.....

There is something that limits black hole growth to 10^10 solar masses.
I'm not sure that I see the problem here. The obvious thing that limits growth is the amount of matter it can gobble up. The totally mass of the Milky Way is 10^12 solar masses. Having the black holes sweep up all of the matter in the middle of the galaxy and then stop after eating up 1% of the galaxy seems not crazy. Also 10^10 solar mass implies about one solar mass per year which raises the question of how much gas a black hole could eat up in one year.

Let me reverse the question. How big would you expect the AGN black holes to be?

Note if dark matter exists the problem becomes more difficult to explain as the black holes should overtime gain mass due to dark matter.
I'm still not sure I see the problem. Can you punch some rough numbers that illustrate the problem? You can estimate the amount of dark matter within say 1 light year of the black hole. I don't think you'll come up with a large number.

The are the peculiar fountain of youth stars that orbit the Milky Way's massive object and curiously also orbit Andromeda's massive object. They are called the fountain of youth stars as they have very short lifetimes do to there size and high temperatures.
That one is pretty easy. You take an old star, strip away it's envelope and you have a new looking star. This also seems to happen in clusters of stars.

Somewhat puzzling is how does one explain the Milky Way's center's massive object's 3.6 x 10^6 solar masses (BH were 10^10 solar masses at z=6) and Andromeda's 30 x 10^6 solar masses. The Milky Way is a relatively large galaxy.
It's actually not. The big monster galaxies are the cD galaxies. Also, it's not clear what the relationship is between the black hole mass and the mass of the galaxy or even it there is one. One problem is that we really have no clue how galaxies formed.

There is also the interesting hypervelocity stars that are also massive hot short lived stars that have speeds in excess of the galaxy's escape velocity.
The current explanation is that a binary star got close to the black hole. Black hole ate one star, the other ran away.
 
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The other issue here is that they are trying to estimate BH mass based on elemental enrichment and maybe that fails if the black hole mass is more than 10^10 solar masses.
 
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One other thing, a lot of the answers I'm giving are "hand waving guesses." In order to really come up with a firm answer on one of the questions you ask, you really need to spend a few years studying the topic. Figuring out exactly how the black hole strips off the envelope of a star to rejuvenate it is a Ph.D. dissertation, and in the course of doing the dissertation someone may find out that there is a some fatal flaw with the those guesses.

One thing about my background, I'm not a quasar specialist, so it's likely that Schild knows more about quasar observations and the magnetic fields in quasars that I do, and with a few weeks of research, you'd probably know more about the subject than me. My area of expertise is core collapse supernova. If Schild wants to argue that you have to have this sort of configuration of magnetic fields in quasars, that's fine, since he knows more about that than me.

The trouble is that if he starts making statements that black holes can't exist because of those field configurations, at that point this impacts things that I have done research on (i.e. magnetic fields in collapsing objects, nuclear EOS, some basic GR, lots of computer science) and what he says just doesn't make any sense to me, and in all of the published papers I've seen, I think he (and Mitra) are fundamentally misinterpreting what the equations say. I'm not getting information from textbooks, but rather it's because I've run computer simulations of collapsing stars with GR.

The basic problem is this. Suppose I am in empty space, and I send out a flash of light every second. Someone a few light years away will see that pulse every second. Now if I get close to a black hole I'll see the pulse of light from the black hole every few seconds, and as I go to the event horizon, the time between pulses of light goes to infinity. However, the really important thing here is that this is an "optical illusion". The person sending the pulse still sees the pulses being sent at one pulse per second, and nothing weird happens to him as she goes through the event horizon. Looking over the equations that Mitra has published, I think that he is taking the "optical illusion" for something that is really going on. The reason that Schild gets right answers in his papers, is that the equations he uses for a MECO are as far as I can tell, exactly the same equations for a black hole. So he gets the observationally correct answers with the wrong model.

There is a physics reason for this. If you have a black hole, then nothing inside of the event horizon should impact anything observable outside the event horizon (that's the definition of the event horizon). So if you have the right equations for what happens at the event horizon (which you do get for these MECO objects), you get the observationally correct answers, even if you are totally, totally wrong about what happens below the event horizon.

The physics that I just mentioned creates "smoking gun." Neutron stars can pulse. Black holes can't. If Schild points to a quasar, and says here is a 10^9 solar mass object that is sending out regular pulses, at that point everyone will go "WHOA!!!!!!" Black holes can have internal magnetic fields. They can't send out regular pulses, at least in any obvious way.

What they have shown is that AGN can have large magnetic fields, and the reaction of people to that is. Hmmmm.... And? Kip Thorne shoed that you can do this. Now if Schild and Mitra comes up with some argument why Kip Throne is wrong (basically what Michel did to the GJ model of pulsars) or someone comes up with some "smoking gun" observational data (i.e. show me a three solar mass or even a two solar mass pulsar), then things get interesting.

Also the physics of black holes is pretty simple. The physics of magnetic fields is horrendously, horrendously complicated. The basic issue is that magnetic forces cause an object to go perpendicular to the field lines and the direction of motion, which causes all sorts of incredibly messy things to happen. If you have a running 1-d computer simulation, it will take you about a day or two to adapt it for GR. Calculating magnetic fields is a multiple year process.

The interesting thing about supernova calculations is that almost none of them use GR, because it turns out that GR matter doesn't matter much, and just makes things more complicated without changing the result. Pretty much all of them leave out magnetic fields, because magnetic fields are too hideously complicated to include.
 
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One other thing is that when I was interviewed for a Wall Street position, one of the interviewers started asking me lots of questions about GR and numerical relativity, particularly about the Van Riper model. It turns out that he did numerical relativity for his Ph.D. It turns out that the skills that you need to figure out what is going on in quasars and supernova are pretty much the same skills that you need to figure out the Nevada real estate market.
 
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Can we focus on mystery at a time :-) :-) :-)

One problem with astrophysics is that there are so many things that we either don't understand or understand poorly that it's hard really have a discussion if we talk about all of them. Now it might be that a lot of the questions are connected in some way, or not.....
You make that statement as do not see any connection in the anomalies.

When you look at observations and anomalies you see them from the standpoint of an assumed theoretical framework. The addition of an intrinsic magnetic field to the massive object is a case in point. That change took 30 years and is not complete.

That methodology (Deal with each anomaly separately and fight every point to the death before thinking about a change. Alternative methodology get the anomalies on the table play with the assumptions.) would be fine if the astronomical observations fit together to support a unified theory with a few anomalies. In the case of astrophysics there are however multiple sets of unexplained and connected fundamental anomalies. The observational data and analysis has advanced to the point that anomalies are being identified as anomalies as opposed to observational errors or statistical oddities and this information is included in recently published textbooks and review papers which makes it possible to analyze the problem holistically and relatively rapidly.

For, example the finding that spiral galaxies have expanded with redshift (Spiral galaxy mass increase does not explain the expansion. Mergers do not explain the expansion.) seems to be irrelevant to a discussion of the central massive object. The spiral galaxy winding paradox would also seem to have no connection. (The spiral arms should based on simulations have wound up creating a disc of stars in a few revolutions. The proposed solution is that the spiral arms are due to density fluctuations does not explain multiple spiral arms and evolution of spiral arms.) The finding that elliptical galaxy star velocity appears to show that elliptical galaxies do not have dark matter surrounding them. (If one throws out the dark matter hypothesis the question then becomes how are spiral and elliptical different in a manner that would affect the rotational properties of the galaxy in question?)

The question of why 70% of galaxies are spiral as compared to elliptical as to what causes a galaxy to be spiral rather than elliptical would seem to have no connection. (The issue is mergers of spirals should produce elliptical galaxies where the stellar orbits are somewhat thermalized and there are multiple rotational axises. i.e. The percentage of galaxies that are spiral should become less with redshift, with an increase in elliptical galaxies as merger of two spiral galaxies should create an elliptical or elliptical like galaxy.

There are sets of different quasar observations that appear to support the assertion that the massive object is not stable with time (I will provide an overview with links to papers) and that material comes out as well as into the object. The stuff that comes out must look like stars however it would have compositional differences.

From an observational standpoint we are limited to the Milky Way however there is observation evidence to support what is observed in the Milky Way's core is also occurring in Andromeda.

Two Discs of Young Stars with Peculiar Orientation and Simultaneous formation times
The anomalies in questions the formation of very young hot peculiar stars in the vicinity of the massive object in the center of the Milky. There are two discs of stars that are at 90 degrees to each other one rotating clockwise and the second counter clockwise. The were both formed at the same time. As they orbit the massive object with two different orbital rotations if we assume a gas cloud origin for the stars, they must have been formed by two independent gas clouds at two slightly different times.


Fountain of Youth Stars
This a different set of young stars that closely orbit the massive object. The issue with these stars is their proximity to the massive object should have suppressed the formation of large stars.


Hyper velocity Stars
For the one example below the ejection angle is 180 degrees to the Milky Way's disc. There is another example were the star in question based on its age and velocity is could not have originated from the massive core.


http://arxiv.org/abs/0710.0139v1

Getting a kick out of the stellar disk(s) in the galactic center
Recent observations of the Galactic center revealed a nuclear disk of young OB stars, in addition to many similar outlying stars with higher eccentricities and/or high inclinations relative to the disk (some of them possibly belonging to a second disk). Binaries in such nuclear disks, if they exist in non-negligible fractions, could have a major role in the evolution of the disks through binary heating of this stellar system. We suggest that interactions with/in binaries may explain some (or all) of the observed outlying young stars in the Galactic center. Such stars could have been formed in a disk, and later on kicked out from it through binary related interactions, similar to ejection of high velocity runaway OB stars in young clusters throughout the galaxy.

Recent observations have revealed the existence of many young OB stars in the galactic center (GC). Accurate measurements of the orbital parameters of these stars give strong evidence for the existence of a massive black hole (MBH) which govern the dynamics in the GC (Eisenhauer et al. 2005). Most of the young stars are observed to be OB stars in the central 0.5 pc around the MBH. Many of them are observed in a coherent stellar disk or two perpendicular disks configurations (Lu et al. 2006; Paumard et al. 2006).

Others are observed to be have inclined and/or eccentric (> 0.5) orbits relative to the stellar disks (hereafter outliers). The inner 0.04 pc near the MBH contain only young B-stars, that possibly have a different origin (e.g. Levin 2007; Perets et al. 2007). It was suggested that the disk stars have been formed a few Myrs years ago in a fragmenting gaseous disk (Nayakshin & Cuadra 2005; Levin 2007). However, the origin of outliers from the disk is difficult to explain in this way. These stars are observed to have very similar stellar properties to the young disk stars (types, lifetimes), but have more inclined and/or eccentric orbits. Many suggestions have been made for the origin of these stars (Milosavljevi´c $ Loeb 2004; Paumard et al. 2006; Alexander et al. 2007; Yu et al 2007, and references therein). Here we suggest a different process in which young stars in the GC stellar disks were kicked into high inclinations and/or eccentricities, in a similar way to OB runaway stars ejected from open clusters. Such a scenario could explain some of the puzzling orbital properties of the young stars in the GC.
http://arxiv.org/abs/astro-ph/0601268v2

The Two Young Star Disks in the Central Parsec of the Galaxy: Properties, Dynamics and Formation

Based on its stellar surface density distribution and dynamics we propose that IRS 13E is an extremely dense cluster (core density > 3x10^8 sunmass/pc^3), which has formed in the counter-clockwise disk. The stellar contents of both systems are remarkably similar, indicating a common age of ~6+/-2 Myr. The K-band luminosity function of the massive stars suggests a top-heavy mass function and limits the total stellar mass contained in both disks to ~1.5x10^4 sunmass. Our data strongly favor in situ star formation from dense gas accretion disks for the two stellar disks. This conclusion is very clear for the clockwise disk and highly plausible for the counter-clockwise system.


The presence of two well defined kinematical systems seems to require two separate events of star formation. This is actually somewhat problematic whatever the formation scenario is, since these two events must have occurred basically at the same time. However, the two events are allowed to be separated by ≃1 Myr from each other. This timespan is sufficient for star formation to remove most of the gas from the first disk before the second one starts forming. The minimum time needed to form stars can be estimated as follows. Once the disk becomes gravitationally unstable, instabilities are believed to grow in the disk on dynamical time scale (e.g. Toomre 1964), i.e. 60 yr (R/1′′)3/2. In addition to that, accretion of gas onto proto-stars is limited by the Eddington accretion rate onto these, which sets the stellar mass doubling time scale to about a thousand years (e.g., Nayakshin & Cuadra 2005). Taken together, these two conditions constrain the minimum duration of the star-formation episode to about 104 yr. Therefore both gaseous disks are not required to have been in the central parsec at the same time. The in situ scenario passes points 1 and 8.

http://arxiv.org/abs/astro-ph/0501177v1

Discovery of an Unbound Hyper-Velocity Star in the Milky Way Halo

The star is either a hot blue horizontal branch star or a B9 main sequence star with a heliocentric distance approx. 55 kpc. Corrected for the solar reflex motion and to the local standard of rest, the Galactic rest-frame velocity is +709 km s−1.

Because its radial velocity vector points 173.8 degrees from the Galactic center, we suggest that this star is the first example of a hyper-velocity star ejected from the Galactic center as predicted by Hills and later discussed by Yu & Tremaine. The star has [Fe/H]_0, consistent with a Galactic center origin, and a travel time of .80 Myr from the Galactic center, consistent with its stellar lifetime. If the star is indeed traveling from the Galactic center, it should have a proper motion of 0.3 mas yr−1 observable with GAIA. Identifying additional hyper-velocity stars throughout the halo will constrain the production rate history of hyper-velocity stars at the Galactic center.
 
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When you look at observations and anomalies you see them from the standpoint of an assumed theoretical framework. The addition of an intrinsic magnetic field to the massive object is a case in point. That change took 30 years and is not complete.
Not true. People have know that massive objects have strong magnetic fields since at least the 1960's. The problem is that there is a big, big difference between knowing that there is a strong magnetic field, and to be able to say something sensible about them. Magnetic fields and plasmas are really, really hard to simulate. The reason that a lot of progress is being made now is that we have tons of observations and computing power that wasn't available in the past.

Compact objects have strong magnetic fields. The problem is *how* to add a magnetic field to a compact object, and that's a hard, hard problem. Hard problems are fun ones.

Also people tend to try to avoid adding magnetic fields to compact objects, not because people know they aren't there.

What you do is that you run your calculations without magnetic fields and *HOPE* it doesn't make a difference, because if it does make a difference, you aren't going to be able to do the calculation at all. So you run the calculation without magnetic fields and see if it makes a difference.

After spending a few years at it, you write papers saying either "I ran the calculation without magnetic fields, and I can answers that see to be close to what we are seeing, so even though we know there are strong magnetic fields there, they don't seem to make a difference" or else "My God, I tried running the calculations without magnetic fields and the numbers I get are obviously totally, totally wrong, so it looks like I'll be spending the next ten years of my life trying to figure out how to add magnetic fields to the calculation." At which point people say "GREAT!!! We've established that magnetic fields do make a big difference!!!! Here's your Ph.D., and you'll have something to do for the next ten years of your life."

You look at things from an assumed theoretical framework, because if you start by assuming something, you can figure out (and you usually do figure out quickly) that your framework just doesn't work. As you eliminate things that just don't work, you end up with things that do.

Also in some situations there is no theoretical framework. We don't have a theoretical framework for galaxy formation. This is bad, because if you don't have a theoretical framework, you don't have anything to prove wrong. We don't really have good theoretical framework for how supernova explode. It's got something to do with neutrinos, convective processes, maybe magnetic fields.

There are sets of different quasar observations that appear to support the assertion that the massive object is not stable with time (I will provide an overview with links to papers) and that material comes out as well as into the object. The stuff that comes out must look like stars however it would have compositional differences.
Maybe. Maybe not. Turning that into a real model as opposed to speculation is going to take a lot of time and effort. Right now galaxy formation and evolution is a really cool field to be in because we don't know what the heck is going on. It's not the situation that we have a standard model and people are trying to find flaws in it. The issue (which is a fun one) is that there is no standard model of galaxy evolution at all, and so we have lots of data that no one knows how to make sense of. Just to ask one out of 100 open questions. People think its interesting that you have galaxy distributions that track the density differences that the CMB indicates.

So you have a situations

We have more dark matter here then (mumble, mumble, mumble) then galaxies form and it has something to do with the massive compact object, and then it has something to do with colliding galaxies (maybe).....

No one quite knows what goes in the (mumble, mumble, mumble). So it appears that galaxies have a black hole in them. So what happened? Did the black hole form first and the stars form around it, or do you have in increase in gas density forming stars and then you have a black hole in the center. Or something else. No one really knows. We'll definitely know a lot more in three years (or even three months).

But you can't fight the standard model of galaxy formation because there is no standard model. Right now we are in the process of trying to come up with a model for galaxy formation, and a lot of the explanations that people have come up sound pretty bogus (population III stars!!!!)

Personally, I like situations where no one knows anything and everyone is just guessing.
 

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