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”
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”,
“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):
“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?”
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  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:
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.
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: