What are the mechanism implications of MECO?

[Saul]

What are the mechanism implications of MECO?

I have been reviewing observational anomalies associated with quasars and spiral galaxy morophology/evolution and thinking about the MECO hypothesis and its implications. I would be interested in eventually discussing them as a set however I am having problems straightening out and organizing the related issues. I am hoping this thread and a second thread I will start later this month will help with that process.

The MECO authors have been making headway to build an observational and theoretical case for the basic MECO model which is a massive compact object that has a very strong attached magnetic field. I have started this thread as a basic summary of the MECO authors’ work and suggest a comparison, pros/cons, similarities/differences: MECO model to the standard classic BH with an accretion disc.

It seems to me that they have got to first base which is to provide sufficient observational evidence to support the assertion that the massive compact object has a massive magnetic field attached it.

In addition to the very specific observational evidence provided in their papers there are a number of fundamental basic quasar observations that support their premise such as the discovery that roughly 10% of quasars are “Naked Quasars” whose spectrum does not include a broad line region type component. (The broad line region is assumed to be emissions from an accretion disc which is the energy source of the classical model. The broad line spectrum is due to the motion of the accretion disc.)

I would suggest you differ reaching any conclusion as to what a MECO is (think of it as a class of possible models) in addition to the MECO Vs Classic BH accretion disk question until you have a chance to think about these specific observations and the observations in the next thread that I will start. (Try to pretend you are seeing the observations for the first time.)

http://iopscience.iop.org/1538-3881/138/2/421

http://arxiv.org/PS_cache/arxiv/pdf/0902/0902.1160v1.pdf

Reverberations in the UV-Optical Macho Quasar 13.5962.237

We examine the nature of brightness fluctuations in the UV-Optical spectral region of an ordinary quasar with 894 optical brightness measurements made during the epoch 1993-1999. We find evidence for systematic trends having the character of a pattern of reverberations following an initial disturbance. The initial pulses have brightness increases of the order of 20% and pulse widths of 50 days, and the reverberations have typical amplitudes of 12% with longer mean pulse widths of the order of 80 days and pulse separations of an order of 90 days. The repeat pattern occurs over the same timescales whether the initial disturbance is a brightening or fading. The lags of the pulse trains are comparable to the lags seen previously in reverberation of the broad blueshifted emission lines following brightness disturbances in Seyfert galaxies, when allowance is made for the mass of the central object. In addition to the burst pulse trains, we find evidence for a semiperiodicity with a timescale of two years. These strong patterns of brightness fluctuations suggest a method of discovering quasars from photometric monitoring alone, with data of the quality expected from large brightness monitoring programs such as Pan-STARRS and LSST.

No physical theory is yet available to guide a discussion of such large quasar structure as implied if the reverberations, observed on time scales of approximately 100 days, are produced by the collapsed central object and propagate to outer luminous structure at light speed. The broad, blue-shifted high-excitation emission lines present in all quasars are presumed in standard theory to originate in clouds randomly orbiting the central structure. A unification model featuring absorption in a dusty torus has no physical basis in kinematic or dynamical theory, although it seems to be required to explain the outflow winds that are revealed in diverse spectroscopic data (Elvis, 2000). Proga (2000) has developed a theory of line driving to explain the outward forces driving an outflow wind but no theory is available to explain why mass is observed so high above the accretion disc plane. However the MECO model of black hole and quasar structure seems to offer a way for strong magnetic fields originating at the center to produce the uplift as a result of magnetic effects caused near the outer light cylinder (Schild, Leiter, and Robertson 2008). In this case the central object would be radiatively inefficient (Robertson and Leiter, 2006), much as standard black hole models also predict.

This is additional specific analysis of two quasars to support their assertion.

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

Direct Mircolensing-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 allowus tomeasure 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 themajor 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.

This is a good summary of the mechanism and theory.

Does Sgr A* Have an Event Horizon or a Magnetic Moment?

Stanley L. Robertson and Darryl J. Leiter

http://journalofcosmology.com/RobetsonLeiter.pdf

 

[Chalnoth]

We'll see in perhaps 5-15 years or so. There are some astronomers working on ultra long baseline interferometry to actually capture an image of the shape of the event horizon of the massive compact object at Sagittarius A*.

As for a magnetic moment, yes, Sagittarius A* is sure to have a magnetic moment. No this isn't evidence for it being a MECO, as it is also expected from a black hole.

 

[Saul]

We'll see in perhaps 5-15 years or so. There are some astronomers working on ultra long baseline interferometry to actually capture an image of the shape of the event horizon of the massive compact object at Sagittarius A*.

As for a magnetic moment, yes, Sagittarius A* is sure to have a magnetic moment. No this isn't evidence for it being a MECO, as it is also expected from a black hole.

http://arxiv.org/abs/astro-ph/0406163v1

Naked active galactic nuclei

In this paper we report the discovery of a new class of active galactic nucleus in which although the nucleus is viewed directly, no broad emission lines are present. The results are based on a survey for AGN in which a sample of about 800 quasars and emission line galaxies were monitored yearly for 25 years. Among the emission line galaxies was the expected population of Seyfert 2 galaxies with only narrow forbidden lines in emission, and no broad lines. However, from the long term monitoring program it was clear that some 10% of these were strongly variable with strong continuum emission. It is argued that these objects can only be Seyfert 1 galaxies in which the nucleus is viewed directly, but in which broad emission lines are completely absent. We compare these observations with other cases from the literature where the broad line region is reported to be weak or variable, and investigate the possibility that the absence of the broad line component is due to reddening. We conclude that this does not account for the observations, and that in these AGN the broad line region is absent. We also tentatively identify more luminous quasars from our sample where the broad emission lines also appear to be absent. The consequences of this for AGN models are discussed, and a case is made that we are seeing AGN in a transition stage between the fuel supply from a surrounding star cluster being cut off, and the nucleus becoming dormant.

There is other observational evidence that the massive compact object has a strong attached magnetic field, for example the discovery of Naked Quasars, however, as I suggested let’s defer trying to making a simple choice of selecting the standard model or MECO.

Let’s back track for a second and re-look at Disney et al’s paper.

http://arxiv.org/abs/0811.1554

I am not sure people are thinking about the theoretical implications of Disney et al’s discovery concerning spiral galaxies. There is evidence of controlled evolution of spirals and the spiral parameters. Rotational velocity is tightly controlled with multiple spiral parameters. There are two general spectral modes.

There appears to be some fundamental mechanism that is missing. The mechanism in question must be able to control and affect multiple parameters in a spiral galaxy.

Assume you did not have the classic BH with an accretion disc model. You were looking at the quasar and massive compact object observations as a set looking for observational evidence to construct a model.

For example in Hawkins’ paper on time dilation of quasars and the first MECO paper quoted above it is noted that the massive compact object is creating long term semi cyclic patterns, with multiple periodicities out to around 2 years.

We have specific assumptions about the massive compact object because we are thinking of the properties of the classical BH and because the quasar observations are not viewed as a set in an organized manner. Start from the observations, defer any theoretical model construction.

Is the massive object compact stable with time? Are we observing something that builds and releases.

The magnetic field of pulsars has been observed to increase with time rather than decrease. As there is no explanation for that observation it is ignored and contested. Are magtars the short term end of a process?

The massive compact objects are observed to have a mass limit of around 10^10 solar masses (Fan’s quasar survey analysis). What is limiting both mass of the massive central object and spiral galaxies? We are looking for a link between something related to teh massive compact object and how it evolves to how the spiral galaxy evolves.


http://www.physics.uci.edu/Cosmology/Fan_Xiaohui.pdf

Evolution of high-redshift quasars

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.

 

[Saul]

We'll see in perhaps 5-15 years or so. There are some astronomers working on ultra long baseline interferometry to actually capture an image of the shape of the event horizon of the massive compact object at Sagittarius A*.

As for a magnetic moment, yes, Sagittarius A* is sure to have a magnetic moment. No this isn't evidence for it being a MECO, as it is also expected from a black hole.

A MECO is not the same as a classical black hole. What are the other observations concerning massive compact objects?

Another approach is to compare the MECO hypothesis (where "MECO" is defined to mean a class of models) to the observations and theory about other massive compact objects. For example "Anomalous X-ray pulsars (AXPs)".

A fundamental difference in the MECO class of models is that the massive compact object is a physical object that has properties that change or could change with time depending on the specific model created. The MECO mechanism implications are we must look at the observations and then construct the model as opposed to the classic BH model.


http://journalofcosmology.com/RobetsonLeiter.pdf

A MECO avoids rapid collapse to a black hole state by radiating away its mass-energy at an Eddington limit rate. It is characterized by both an extreme redshift and a strong intrinsic magnetic moment (see Appendix A - C).

We show below that the MECO model is consistent with the low luminosity constraints observed for Sgr A* (Broderick and Narayan 2006, hereafter BNO6, Broderick, Loeb & Narayan 2009, hereafter BLN09)

For the extreme redshift of the MECO, the photosphere of its pair atmosphere lies deep within the photon sphere (see Appendix A, B, C). The photosphere is the last scattering surface of the pair plasma atmosphere, however, it should be noted that the escape cone from the photosphere is so small that most of the photons that arrive there still do not escape. The pair atmosphere is maintained in part by a magnetic field of approx. 10^20 G (RLO3) which is strong enough to create bound pairs (Harding 2003, Zaumen, 1976) on a deeper lying baryon surface. The interior magnetic field is much smaller, as required by the Maxwell-Einstein boundary condition (see Appendix B). The ratio of surface to interior magnetic field strength is what determines the MECO redshift for the mass of Sgr A* to be (1+zs) approx. 10^11.

http://arxiv.org/PS_cache/astro-ph/pdf/0307/0307133v1.pdf

Origin and Evolution of Neutron Star Magnetic Fields

(Presented to a 2008 conference of specialists on the Origin and Evolution of Neutron Star Magnetic Fields)

Anomalous X-ray pulsars (AXPs) show persistent X-ray emission, modulated at a stable, slowly lengthening period. Contrary to the standard, binary X-ray pulsars (§2.3), they show no evidence for a companion star (see Mereghetti & Stella 1995; van Paradijs, Taam, & van den Heuvel 1995; Mereghetti 2000).

The dipole fields inferred from the spin-down rate are 10^14−15 G (Kouveliotou et al. 1998; Hurley et al. 1999), much larger than in previously known classical pulsars, though radio pulsars with similar inferred dipole fields have recently been found (Camilo et al. 2000; McLaughlin et al. 2003). In addition, features in the X-ray spectra of both SGR 1806-20 (Ibrahim et al.2002) and AXP 1RXS J170849-400910 (Rea et al. 2003), interpreted as proton cyclotron resonance lines (Ibrahim et al. 2003), indicate B approx. 10^15 G, in reasonable agreement with the inferred dipole fields.

Perhaps most importantly, the persistent X-ray luminosity of these objects is much larger than their inferred spin-down power. Therefore, unlike the case of radio pulsars, rotation can not be a significant energy source. It has long been suggested that magnetic energy may be the ultimate source of both the bursts and the persistent radiation (Duncan & Thompson 1992; Paczynski 1992; Thompson & Duncan 1995, 1996), but this would still require a total magnetic energy significantly larger than inferred from the dipole field, i.e., a buried and/or disordered magnetic flux. In any case, the strong magnetic field may modify the radiation transport in the surface layers, so that these objects radiate a much larger fraction of their fossil heat in X-rays (as opposed to neutrinos) than less magnetic neutron stars (van Riper 1988; Heyl & Hernquist 1997a, b).

Research on magnetic fields in neutron stars is undoubtedly in one of its most interesting moments. Little is known about the strength, structure, origin, and evolution of the field, but there seems to be little doubt that it plays a fundamental role in determining the increasingly rich phenomenology of these objects. The coming years will most probably improve our understanding of the “magnetars” and “thermal emitters”, hopefully contributing to a coherent picture of how these new subclasses fit together with the more traditional radio pulsar and X-ray binary groups and with other kinds of stars.

http://en.wikipedia.org/wiki/SGR_1806-20

SGR 1806-20 is a magnetar, a particular type of neutron star. It has been identified as a soft gamma repeater. SGR 1806-20 is located about 14.5 kiloparsecs (50,000 light-years) from Earth on the far side of our Milky Way galaxy in the constellation of Sagittarius. It has a diameter of no more than 20 kilometres (12 miles) and rotates on its axis every 7.5 seconds (30,000 km/h rotation speed at the surface). As of 2007, SGR 1806-20 is the most magnetic object ever perceived by humankind, with a magnetic field over 1015 gauss (1011 teslas) in intensity [1] (compared to the Sun's 1-5 gauss). SGR 1806-20 has a magnetic field that is a quadrillion times stronger than that of the Earth.

SGR 1806-20 lies at the core of radio nebula G10.0-0.3 and is a component of cluster 1806-20, itself a component of W31, one of the largest H II regions in the Milky Way. Cluster 1806-20 is made up of some highly unusual stars, including at least two carbon-rich Wolf-Rayet stars (WC9d and WCL), two blue hypergiants, and one of the brightest/most massive stars in the galaxy LBV 1806-20.

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

Michel's summary paper was recommend as reading material at the end of magnetar presentation.

The State of Pulsar Theory
I summarize the status of pulsar theory, now 35 years after their discovery. Although progress has been made in understanding the relevant processes involved, there are several widely held misconceptions that are inhibiting further advances. These include the idea that plasma “must” be accelerated from the magnetic polar caps (the basis for the “Hollow Cone Model”) and the idea that winds would be driven away by centrifugal forces, with large amplitude electromagnetic waves playing no role whatsoever. 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).

 

[Chalnoth]

A MECO is not the same as a classical black hole.

I am aware.

What are the other observations concerning massive compact objects?

Unfortunately this is a bit outside my field of study. However, a good rule of thumb with things like this is to take a "wait and see" approach until some really solid observations are available. The best that you've prevented so far is evidence that can be considered, "Yeah, I can sort of see how that might be reasonable," instead of a real smoking gun. When we get some extremely long baseline interferometry of Sagittarius A*, then we'll know for sure, one way or another.

I will comment, however, that I've seen talks from people who are studying this sort of thing and still consider black holes as the only likely end result of gravitational collapse for sufficiently massive objects. I don't know whether that's because this solution of the Einstein equations hasn't received much publicity, whether it's considered highly speculative, or whether it's basically been shown to be wrong. In any case, a wait and see approach is warranted.

 

[Chronos]

Observations affirmed by theory are less compelling than theory confirmed by observations. Prediction is the hallmark of any good theory. You can backfit most any set of observations to some sort of theory. Turning that theory into a predictive tool is the test.

 

[Saul]

Observations affirmed by theory are less compelling than theory confirmed by observations. Prediction is the hallmark of any good theory. You can backfit most any set of observations to some sort of theory. Turning that theory into a predictive tool is the test.

I agree a prediction is a valid test.

What we are asking or should be asking is why has the problem not been solved todate (35 years of observations, some of the greatest minds on the planet working on the problem). The failure is due to faulty methodology. One cannot start with a guess theory/mechanism that was created before there were observations to provide some sort of guide to the correct mechanism/theory and then try to adjust the guess model to fit the observations, if the objective is to solve the problem.

After 35 years there is no smoking gun support for a new mechanism and there are multiple sets of unexampled anomalies which are not discussed in standard textbooks (i.e. The textbook includes the standard toy model that the specialists know cannot explain the observations however the toy model is easy to explain and can be used to produce simple examine questions, so it used and passed on.)

There are fundamental problems: explaining blue stragglers, explaining the paradox of youth stars, pulsars and magnetars, metallicity variance in our galaxy and in other galaxies, quasar properties and quasar property variance with redshift, star burst galaxies, the spiral winding problem, Disney’s finding that spiral galaxies are simpler than expected, and so on. It appears there is some missing mechanism that is controlling spiral galaxies and details concerning stellar formation and stellar evolution in the spiral galaxies. Perhaps if one understood what that mechanism was then it would possible to explain why there is the observed morphological differences between spiral and elliptical galaxies, Disney’s observations concerning spirals, the evolution and morphological differences of spiral galaxies.

If you review astrophysical observations at a detailed level (stars, galaxies, clusters and evolution of the same with redshift.) what is observed does not make sense. i.e. There are multiple anomalies. The anomalies seem to be connected. What is interesting about this field is there are detailed observational and theoretical model review papers that summarized in 30 to 40 page, 20 to 30 years of research.


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

 

[Chalnoth]

As with other things we've gone over here, there are large technical problems involved in properly simulating the physics of stars, especially compact stars like neutron stars. These technical problems prevent us from having that much confidence in our models of these stars in the first place. So it is difficult, at best, to pin a discrepancy on their behavior down to a misunderstanding of fundamental physics.