Monthly Archives: April 2012

The Genesis of ”Magnetospheric Eternally Collapsing Object”

In 1998, I happened to be the first physicist to coin the term ”Eternally Collapsing Object” (ECO) in the preprint entitled:

”Final State of Spherical Gravitational Collapse and Likely Source of Gamma Ray Bursts”

http://arxiv.org/abs/astro-ph/9803014

I found that a collapsing star should not ever become a strict (finite mass) Black Hole. Normally, one would interpret this as a signature of formation of a  ”Naked Singularity”. But a ”Naked Singularity” would be a spacetime singularity only if it would form in a finite comoving proper time. But my hunch was that the star would take infinite proper time to collapse to a geometrical point because increasing grip of gravity would stretch the spacetime membrane indefinitely.

On the other hand, the collapsing star must attain an ultra-compact quasi-static configuration in a finite time due to resistive effects such as tangential pressure and radiation pressure. But in a strict sense, this ultra-compact object would keep on contracting at an infinitesimal rate to attain the mathematical solution of a ”Black Hole”. And hence, I termed this ultra-compact static object, which is mis-interpreted as ”Black Hole” by astronomers as ”ETERNALLY Collapsing Object”.

In this 1998 paper, I wrote

“Much more importantly, the ECOs may possess magnetic fields whose value could be either modest (in extragalactic cases) or extremely high (in stellar mass ECOs). In contrast, the intrinsic magnetic field of supposed BHs is zero. And ECOs might be identified as objects different from BHs by virtue of the existence of such intrinsic magnetic fields.”

Similarly,  the paper, “Non-occurrence of trapped surfaces and Black Holes in spherical gravitational collapse: An abridged version”,

A. Mitra, Found.Phys.Lett. 13 (2000) 543
http://arxiv.org/abs/astro-ph/9910408

mentioned that

“while a BH cannot have any intrinsic magnetic field, an UCO/ECO could be highly magnetized and thus the latter is much more capable to explain likely beamed emission.”

Essentially, I envisaged the ECOs to be ultra-magnetized objects, and in particular stellar mass ECOs to possess a magnetic field much stronger than that of Pulsars. Now, it is known that all magnetized astrophysical objects possess a magnetosphere where charged particles remain trapped. The most common example is Earth’s magnetosphere where charges arise from cosmic rays or solar winds:

And if the magnetized object spins it can extricate charges from its own body, as is the case for pulsars.

Thus, though I did not use the term ”Magnetospheric ECO” or ”MECO” in 1998,the idea of a MECO was born right then.

The preprints of the papers challenging the idea of trapped surfaces, singularities and revered black holes were on the net since 1998, and I had to struggle to get one them published. These phase was keenly watched by many relativists and astrophysicists, and probably nobody thought that any established referee would ever allow their publication in a journal like Foundations of Physics with a distinguished editorial board. Yet when the paper got accepted by two referees, I received many congratulatory emails from various relativists who had always been suspicious about the notion of a “Black Hole”.

In particular, following this, I developed intense and ever lasting academic interaction with Dr Stanley  Robertson and Dr Darryl Jay Leiter.

Darryl was originally a Ph.D. in elementary particle physics from Brandes University. But his interest spanned Relativistic Astrophysics. He taught at Boston College, the University of Windsor, Central Michigan University, and George Mason University, and received numerous research grants, including two senior fellowships at NASA. However, when he contacted me, he was working as a research scientist in a laboratory related to US army (FSTC Charlottesville, VA). On the other hand, Stan was a Professor in Southwestern Oklahoma State University.  Stan had earlier worked  in the framework of “Bimetric Theory” of Nathan Rosen in the hope of finding Black Hole Alternative. They thought that BHs cannot be exorcised by relying on plain General Relativity. And they got very excited by seeing that GR itself rather than somewhat adhoc bimetric theory can eliminate BHs. We started exchanging fervent emails on various aspects of related physics and  soon, Stand & Darryl produced a very important paper:

Evidence for Intrinsic Magnetic Moments in Black Hole Candidates

The Astrophysical Journal, Volume 565, Issue 1, pp. 447-454 (2002):

http://arxiv.org/pdf/astro-ph/0102381v2.pdf

“Although the existence of objects compact enough to qualify as black hole candidates is beyond question and the existence of black holes is accepted by most astrophysicists, it is still observationally unclear whether event horizons can be physically realized in the collapse of stellar mass objects. Hence it is still necessary that we be able to exclude the possibility that GBHC might be intrinsically magnetized objects before we can say that they truly are black holes. It has recently been suggested (Mitra 2000) that, within the framework of General Relativity, trapped surfaces cannot be formed by collapse of physical matter and radiation. Such a view was also held by Einstein (1939).”

Here ECO remained ECO and not explicitly MECO.

Following our fervent email exchanges, on  21 Nov 2001, Darryl, Stan and I posted a preprint entitled:

”Does The Principle Of Equivalence Prevent Trapped Surfaces From Being Formed In The General Relativistic Collapse Process?”

http://arxiv.org/abs/astro-ph/0111421v1

The abstract of this preprint started as follows:

“It has been recently shown [Mitra, 2000] that timelike spherical collapse of a physical fluid in General Relativity does not permit formation of “trapped surfaces’’. This result followed from the fact that the formation of a trapped surface in a physical fluid would cause the timelike worldlines of the collapsing fluid to become null at the would be trapped surface, thus violating the Principle of Equivalence in General Theory of Relativity (GTR).”

Here we mentioned that the strong intrinsic magnetic field of ECOs should cause Propeller Action on the plasma accreting onto it; and this is the way the state transitions in the so-called black hole candidates in the X-ray binaries is to be explained.

We wrote this draft rather hurriedly and  went on deliberating about improving  the model of magnetized ECOs for the next 6 months. I wanted to keep the ECO magnetic field as a free parameter which would vary from case to case. Recall, we know that while Pulsars can have strong magnetic field, there is no way one can pin down the precise value of B for  a given pulsar from a basic theoretical framework. In particular, B does not depend on Pulsar mass. And although all the pulsars have nearly the same mass, their B may vary over 5 orders of magnitude: from 10*** Gauss to 10**13 Gauss.

On the other hand, Stan and Darryl wanted to build a loose model of ECOs where they hoped they could predict the magnetic field of ECOs in a certain theoretical model. Further they thought that the ECO B would be depend in a precise manner on its mass M.

The abstract of the 2nd draft of this preprint formally used the term “Magnetospheric ECO” for the first time:

“In this context the spectral characteristics of galactic black hole
candidates offer strong evidence [3] that their central nuclei are highly red shifted Magnetospheric Eternally Collapsing Objects (MECO), within the framework of General Relativity.”

While Stan & Darryl were very very keen that I continue to be the coauthor for this paper, I dropped out as I thought that as in the case of Pulsars, the ECO magnetic field cannot be uniquely calculated by any precise theory.

Meanwhile my another paper entitled “On the final state of spherical gravitational collapse”

Mitra, A., (2002),  Foundations of Physics Letters, Volume 15, Issue 5, pp.439-471 , (astro-ph/0207056)

got published and where I exerted that

“Note that, if the BHCs were really BHs, they would not have had any intrinsic magnetic field whereas if they are Eternally Collapsing Objects (ECOs) or static Ultra Compact Objects (UCOs) with physical surface they are expected to have such strong intrinsic magnetic fields.”

Thus the 2nd draft of  our original joint  paper got posted on 29 Aug 2002 without bearing my name:

http://arxiv.org/abs/astro-ph/0111421v2

Eventually, the 3rd draft of this paper got published in Foundations of Physics Letters.

Had I wanted, I could very well remained a coauthor of this published paper; but I dropped out only because of purinitical  attitude to physics. Thus I was very much a party to the coining of the term “Magnetospheric ECO” even though my name did not appear in the relevant journal paper.

And the  model of a “Magnetospheric ECO” or “MECO” purused by Stan & Darryl is only a particular model based on their calculations and various assumptions. This is something like one is using a certain model for the growth or decay of say Pulsar Spin or Magnetic Field. Just like the notion of a magnetized pulsar is a generic concept, the idea of a magnetized ECO too is a generic concept.

Thus a subsequent comment by Darryl & Stan that

“Our finding challenges the accepted view of black holes,” said Leiter. “We’ve even proposed a new name for them – Magnetospheric Eternally Collapsing Objects, or MECOs,” a variant of the name first coined by Indian astrophysicist Abhas Mitra in 1998.

http://www.cv.nrao.edu/tuna/past/2006/NEW_QSO_STRUCTURE_FOUND.pdf

is not factually correct. The name “MECO” was jointly coined by all three of us during the preparation of the 2nd draft of  ”Does The Principle Of Equivalence Prevent Trapped Surfaces From Being Formed In The General Relativistic Collapse Process?”

Similarly, the notion that “MECO” was the idea of (only) Robertson & Leiter too is incorrect. Apart from the fact that the generic notion of a MECO came first in 1998, we three kept on discussing various aspects of the particular MECO model developed by Robertson & Leiter. For instance if one would work with a particular model of Pulsar, it cannot be said that he gave the idea of pulsars by superseding the original idea.

Nonetheless, for connecting theory with observations, one needs to make models even though such models may have subtle inaccuracies and somewhat unsubstantiated assumptions. And the model of MECO of Robertson & Leiter has been been very much correct on broad qualitative terms; in general, it has been quite successful and  greatly enhanced the astrophysical appeal of ECOs. I think their contribution to be a milestone in Relativistic Astrophysics.

WARNING: The present form of the wikipedia article on “MECO” is a mischievous attempt to discredit the solid physics behind MECO by mis-informations, and distortions. The malicious wiki editors deleted all peer reviewed authentic citations and replaced them with  unauthentic junks available on the net.

And I am very sad that Darryl fell prey to cancer on March 4, 2011 and departed prematurely. But I am sure his scientific contributions will always be remembered and valued:

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Coronal Mass Ejection From Sun, MECOs and Quasars

By definition “nothing not even light can escape from” a “Black Hole”. On the other hand, it has been shown that the astrophysical “Black Hole Candidates” or anything else with a finite (gravitational) mass cannot be true BHs simply because true BHs have zero gravitational mass (A. Mitra, Journal of Mathematical Physics, Volume 50, Issue 4, pp. 042502-042502-3 (2009)):

http://arxiv.org/pdf/0904.4754v1.pdf

Further, it has been shown that the BHCs are likely to be ultra-magnetized, ultra-compact balls of fire/plasma called “Magnetospheric Eternally Collapsing Objects” (MECOs).

Though a fictitious BH (with supposed finite mass) can accrete matter, not much variability is expected around it because BHs do not have intrinsic magnetic field and “nothing can escape” from this dead object. In contrast MECOs are live and kicking. The magnetized plasma of MECO can cause astrophysical violence on a scale much more gigantic as compared to the Sun. And indeed BHCs in Quasars/ X-ray Binaries are much more violent and variable as compared to not only the Sun but even pulsars and Neutron Stars.

Thus it was interesting for me to note a discussion which indeed tries to connect MECOs with Quasars and Coronal Mass Ejection from the Sun:

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“There is an immense magnetic field associated with quasars (See the paper by Stanley Robertson, Darryl Leiter) . A classical black hole cannot create a magnetic field and the magnetic field is stronger than accretion disk is capable of creating and is located in region of that is significantly closer the black hole that accretion disk can possible exist at.)

Classical black holes have no hair (they cannot contain a magnetic field). Very large objects when they collapse do not form a classical black hole. (See Robertson & Darryl Leiter’s paper for details.) A quantum mechanic phenomena arrests the collapsing object by forming a very, very, strong magnetic field that stops the collapse as the field creates electron/positron pair in the vacuum. The collapsed object is not stable and over time breaks apart, ejecting pieces of the super compressed collapsed object and dust. (There are massive dust clouds about quasars.) Evidence of this is Hawkins’ long term observation of quasars that found that they pulsate periodically at very long time scales (months and years) and the pulsation increase in amplitude. (All of the observed quasar pulsation increase in amplitude which indicates that there is a fundamental property and mechanism that is observed.)

What happens to massive objects when they collapse is a fundamental component in explaining a host of astronomical anomalies such as the rotational anomaly of spiral galaxies as well the very existence of spiral galaxies as compared to elliptical galaxies.

The orbital cycles of the planets influence the sun as the sun changes with time. There is a charge change. The planets take time to equalize to the change. There is a lag. There is a gradual change in solar charge with time as the cycle progresses which explains phenomena that is dependent on the length of the solar cycle. Follow the interruption of the solar magnetic cycle there are abrupt very large charge discharges. The interruption of the sun spot mechanism, stops the solar equalization mechanism which then allows the solar charge in balance to build up.

The Magnetospheric Eternally Collapsing Object (MECO) Model of Galactic Black Hole Candidates and Active Galactic Nuclei by Stanley Robertson, Darryl Leiter

http://arxiv.org/PS_cache/astro-ph/pdf/0602/0602453v1.pdf

The similarities of NS and GBHC properties, particularly in low and quiescent states, have been previously noted, [e.g. van der Klis 1994, Tanaka & Shibazaki 1996]. Jets and their synchrotron emissions in NS, GBHC and AGN also have obvious magnetic signatures. It is axiomatic that astrophysical objects of stellar mass and beyond have magnetic moments if they are not black holes, but an intrinsic magnetic moment is not a permissible attribute of a black hole. Yet in earlier work, [Robertson & Leiter 2002] we presented evidence for the existence of intrinsic magnetic moments of ∼ 1029−30 gauss m^3 in the galactic black hole candidates (GBHC) of low mass x-ray binary (LMXB).

Others have reported evidence for strong magnetic fields in GBHC. A field in excess of 10^8 G has been found at the base of the jets of GRS 1915+105 [Gliozzi, Bodo & Ghisellini 1999, Vadawale, Rao & Chakrabarti 2001]. A recent study of optical polarization of Cygnus X-1 in its low state [Gnedin et al. 2003] has found aslow GBHC spin and a magnetic field of ∼ 10^8 gauss at the location of its optical emission. These field strengths exceed disk plasma equipartition levels, but given the r^−3 dependence of field strength on magnetic moment, the implied magnetic moments are in very good agreement with those we report in Table 1.

Although there are widely studied models for generating magnetic fields in accretion disks, they can produce equipartition fields at best [Livio, Ogilvie & Pringle 1999], and perhaps at the expense of being too luminous [Bisnovatyi-Kogan & Lovelace 2000] in quiescence and in any case, too weak and comoving in accretion disks to drive jets. While tangled magnetic fields in accretion disks are very likely responsible for their large viscosity, [e.g. Hawley, Balbus & Winters 1999] the highly variable mass accretion rates in LMXB make it unlikely that disk dynamos could produce the stability of fields needed to account for either spectral state switches or quiescent spin-down luminosities. Both require magnetic fields co-rotating with the central object. Further, if disk dynamos produced the much larger apparent magnetic moments of GBHC, they should produce them also for the NS systems and cause profound qualitative spectral and timing differences from GBHC due to interactions with the intrinsic NS magnetic moments.

http://arxiv.org/abs/astro-ph/0505518

Observations Supporting the Existence of an Intrinsic Magnetic Moment Inside the Central Compact Object Within the Quasar Q0957+561 by Rudolph Schild, Darryl Leiter, Stanley Robertson

This latter discovery was revealed in the following manner: a) First it was argued (Robertson and Leiter, 2002) that the spectral state switch and quiescent luminosities of low mass x-ray binaries, (LMXB) including GBHC, can be well explained by a magnetic propeller effect that requires an intrinsically magnetized central object. b) Second it was shown (Leiter and Robertson, 2003; Robertson and Leiter, 2003) that this result was consistent with the existence of a new class of gravitationally collapsing solutions of the Einstein field equations in General Relativity which describe highly red shifted, magnetospheric, Eternally Collapsing Objects (MECO) that do not have trapped surfaces leading to event horizons. These general relativistic MECO solutions were shown to emerge from the physical requirement that the structure and radiation transfer properties of the energy-momentum tensor on the right hand side of the Einstein field equations for a collapsing object must contain equipartition magnetic fields that generate a highly redshifted Eddington limited secular collapse process which satisfies the Strong Principle of Equivalence (SPE) requirement of time like world line completeness.

http://iopscience.iop.org/1538-3881/129/2/615/fulltext/

STRUCTURE FUNCTION ANALYSIS OF LONG-TERM QUASAR VARIABILITY

The cause of the long-term variability in quasars is still a matter of debate. Unlike the short-timescale variations (on the order of days), which are adequately described in terms of relativistic beaming effects (e.g., Bregman et al. 1990; Fan & Lin 2000; Vagnetti et al. 2003), the variations at much longer timescales (years to decades) are less well understood. Current scenarios under consideration range from source intrinsic variations due to active galactic nucleus (AGN) accretion disk instabilities (DIs; e.g., Shakura & Sunyaev 1976; Rees 1984; Siemiginowska & Elvis 1997; Kawaguchi et al. 1998; Starling et al. 2004) and possible bursts of supernovae events close to the nucleus (e.g., Terlevich et al. 1992; Cid Fernandes et al. 1996), to source extrinsic variations due to microlensing events along the line of sight to the quasar (e.g., Hawkins 1993, 2002; Alexander 1995; Yonehara et al. 1999; Zackrisson et al. 2003). See also the review article by Ulrich et al. (1997).

Determining which of the various proposed mechanisms actually dominates quasar variability is best done by studying it toward the longest possible time baselines. Depending on the mechanism, each has markedly different variability “power” at  the longer timescales (e.g., Hawkins 2002). This means that if one has a quasar monitoring sample that is both large enough and covers a large enough time baseline, one could address these issues adequately. Unfortunately, given the nature of monitoring programs, this is not something that can be started overnight. The longest quasar light-curve monitoring programs are on the order of 20 yr (e.g., Hawkins 1996) and will take a long time before they are expanded significantly in time baseline.

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REFERENCE: http://wattsupwiththat.com/2012/03/29/potential-for-large-solar-flares-and-cmes-may-be-with-us-again-soon/