Stanley L. Robertson

Evidence for Intrinsic Magnetic Moments in Black Hole Candidates

We present evidence that the power-law part of the quiescent X-ray emissions of neutron stars in low-mass X-ray binaries is magnetospheric in origin. It can be very accurately calculated from known rates of spin and magnetic moments obtained from the ~103-104 times brighter luminosity at the hard spectral state transition. This strongly suggests that the spectral state transition to the low hard state for neutron stars is a magnetospheric propeller effect. We test the hypothesis that the similar spectral state switches and that quiescent power-law emissions of the black hole candidates might be magnetospheric effects. In the process we derive proposed magnetic moments and rates of spin for them and accurately predict their quiescent luminosities. This constitutes an observational test for the physical realization of event horizons and suggests that they may not be formed during the gravitational collapse of ordinary matter.

Observations Supporting the Existence of an Intrinsic Magnetic Moment inside the Central Compact Object within the Quasar Q0957+561

Recent brightness fluctuation and autocorrelation analysis of time series data and microlensing size scales, seen in Q0957+561A and B, have produced important information about the existence and characteristic physical dimensions of a new nonstandard magnetically dominated internal structure contained within this quasar. This new internal quasar structure, which we call the Schild-Vakulik structure, can be consistently explained in terms of a new class of gravitationally collapsing solutions to the Einstein field equations that describe highly redshifted Eddington-limited magnetospheric eternally collapsing objects that contain intrinsic magnetic moments. Since observations of the Schild-Vakulik structure within Q0957+561 imply that this quasar contains an observable intrinsic magnetic moment, this represents strong evidence that the quasar does not have an event horizon.

On Intrinsic Magnetic Moments in Black Hole Candidates

In previous work we found that many of the spectral properties of low mass x-ray binaries, including galactic black hole candidates could be explained by a magnetic propeller model that requires an intrinsically magnetized central object. Here we describe how the Einstein field equations of General Relativity and equipartition magnetic fields permit the existence of highly red shifted, extremely long lived, collapsing, radiating objects. We examine the properties of these collapsed objects and discuss characteristics that might lead to their confirmation as the source of black hole candidate phenomena.

On the origin of the universal radio–X-ray luminosity correlation in black hole candidates

In previous work, we found that the spectral state switch and other spectral properties of both neutron stars (NSs) and galactic black hole candidates (GBHCs) in low-mass X-ray binary systems could be explained by a magnetic propeller effect that requires an intrinsically magnetic central compact object. In later work, we showed that intrinsically magnetic GBHCs could be easily accommodated by general relativity in terms of magnetospheric eternally collapsing objects (MECOs), with lifetimes greater than a Hubble time, and examined some of their spectral properties. In this work, we show how a standard thin accretion disc and corona can interact with the central magnetic field in atoll class NSs, and GBHCs and active galactic nuclei (AGN) modelled as MECOs, to produce jets that emit radio to infrared luminosity L R that is correlated with mass and X-ray luminosity as L R oc M 0.75-0.92 L 2/3 x up to a mass scale invariant cut-off at the spectral state switch. Comparing the MECO-GBHC/AGN model to observations, we find that the correlation exponent, the mass scale invariant cut-off and the radio luminosity ratios of AGN, GBHCs and atoll class NSs are correctly predicted, which strongly implies that GBHCs and AGN have observable intrinsic magnetic moments and hence do not have event horizons.

X-RAY NOVAE, EVENT HORIZONS, AND THE EXPONENTIAL METRIC

Recent work has shown that the spinning magnetic fields of neutron stars (NSs) can cause soft/hard spectral state switches. The spectral state switches of black hole candidates (BHCs) could be produced in the same way. Spin frequencies and magnetic field strengths are estimated for them. Spins below 100 Hz and fields above 1010 G can account for their spectral state switches and their quiescent luminosities. It also appears that large flickering amplitudes and ultrasoft spectral peaks would be expected from radiating surfaces of massive NSs. Since BHCs share most of their spectral properties with NSs and there is as yet no proof of event horizons, the possibility that they might simply be massive NSs must be considered seriously. This opens an avenue for proof by negation but requires the use of a spacetime metric that has no event horizon. The Yilmaz exponential metric used here is shown to have an innermost marginally stable orbit with radius, binding energy, and Keplerian frequency that are within a few percent of the same quantities for the Schwarzschild metric. A maximum NS mass of ~10 M☉ is found for the Yilmaz metric. Since the two metrics essentially differ only by the presence/absence of a surface for the BHCs it should at last be possible to prove or disprove the existence of event horizons.

Bigger Bursts from Merging Neutron Stars

GRB 990123 may have produced 4×1054 ergs in gamma rays unless, as seems to be the case, it was significantly beamed. Even with beaming, it may be beyond the limiting binding energy available for neutron star mergers in the Schwarzschild metric. Neutron stars of ~10 M☉ are permitted in the Yilmaz metric. A merger of two neutron stars of about 10 M☉ could release approximately 3×1055 ergs. The spectral state switches of the galactic black hole candidates may be the signatures of the magnetic fields of such massive neutron stars.

Does the Principle of Equivalence Prohibit Trapped Surfaces from Forming in the General Relativistic Collapse Process

It has recently been shown that time-like 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 time-like world lines 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). For the case of the spherical collapse of a physical fluid, the “no trapped surface condition” 2GM(r, t)/R(r, t) c2<1 was found to be required to be satisfied in all regions of spacetime, where R(r, t) is the invariant circumference variable, r is a co-moving radial coordinate and M(r, t) is the gravitational mass confined within the radius r. The above result was obtained by treating the problem from the viewpoint of an internal co-moving observer at radius r. The boundary of the fluid at rs=Rs(rs, t) must also behave in a similar manner, and an external stationary observer should be able to obtain a similar “no trapped surface” relationship. Accordingly, we generalize this analysis by studying the problem of a time-like collapsing radiating plasma from the point of view of the exterior stationary observer. We find the Principle of Equivalence implies that the physical surface surrounding the plasma must obey 1/(1+zs)>0, where zs is the surface red shift seen by a zero-angular momentum observer. When this condition is applied to the first integral of the time-time component of the Einstein equation, it leads to the “no trapped surface condition” 2GM(rs, t)/R(rs, t) c2<1 consistent with the condition obtained above for the interior co-moving metric. The Principle of Equivalence enforces the “no trapped surface condition” by constraining the physics of the general relativistic radiation transfer process in a manner that requires it to establish and maintain an Eddington limited secular equilibrium on the dynamics of the collapsing radiating surface so as to always keep the physical surface of the collapsing object outside of its Schwarzschild radius. The important physical implication of the “no trapped surface condition” is that galactic black hole candidates GBHC do not possess event horizons and hence do possess intrinsic magnetic fields. 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.

Revised densities of methane to 10 kbar and 200 °C

The adoption of new calibration densities at low pressures leads to greatly improved accuracy for densities at high pressures.