Related papers: Magnetospheric Eternally Collapsing Objects (MECOs…
We estimate that the vacuum electric field associated with a spinning Magnetospheric Eternally Collapsing Object MECO (www.phys.uni-sofia.bg/~astro/abbrev.html) could be higher by a factor of ~ 10^4 than the corresponding pulsar value…
The spectral, timing, and jet formation properties of neutron stars in low mass x-ray binary systems are influenced by the presence of central magnetic moments. Similar features shown by the galactic black hole candidates (GBHC) strongly…
It is shown here that the so-called spinning Black Hole Candidates (BHCs) cannot be Black Holes (BHs) at all and, on the other hand, must be spinning hot Eternally Collapsing Objects (ECOs). The question would then arise why the spinning…
There are many observational evidences for the existence of massive compact condensations in the range $10^6 -10^{10} M_\odot$ at the core of various galaxies. At present such condensations are commonly interpreted as Black Holes (BHs).…
In previous work we found that many of the spectral properties of low mass x-ray binaries (LMXB), including galactic black hole candiates (GBHC) were consistent with the existence of intrinsically magnetized central objects. We review and…
Magnetic Eternally Collapsing Objects (MECO) have been proposed as the central engines of galactic black hole candidates (GBHC) and supermassive active galactic nuclei (AGN). Previous work has shown that their luminosities and spectral and…
We study collision of particles in the vicinity of a horizon of a weakly magnetized non-rotating black hole. In the presence of the magnetic field innermost stable circular orbits (ISCO) of charged particles can be located close to the…
Magnetically charged black holes (MBHs) are interesting solutions of the Standard Model and general relativity. They may possess a "hairy" electroweak-symmetric corona outside the event horizon, which speeds up their Hawking radiation and…
In a recent paper (FPL 13(6), 543, 2000, astro-ph/9910408), from several independent considerations we showed that GTR does not allow formation of trapped surfaces and finite mass BHs. We rediscuss here several subtle issues involved in…
We propose the existence of ultracompact minihalos as a new type of massive compact halo object (MACHO) and suggest an observational test to discover them. These new MACHOs are a powerful probe into the nature of dark matter and physics in…
We show that the integration constant in the vacuum Schwarzschild solution has the unique value, alpha_0=0, accordingly Black Holes too have the same unique value of mass M0=0. Therefore the so-called Black Holes Candidates (BHC) cannot be…
Binary coalescences are known sources of gravitational waves (GWs) and they encompass combinations of black holes (BHs) and neutron stars (NSs). Here we show that when BHs are embedded in magnetic fields ($B$s) larger than approximately…
Black hole mimickers (BHMs) are horizonless globally regular ultracompact relativistic self-gravitating objects (UCOs) of mass $M$ and radius $R$ with compactness $C = M/R$ higher than that of a neutron star and that produce an effective…
It has been justifiably questioned that if the Black Hole Candidates (BHCs) have a ``hard surface'' why Type I X-ray bursts are not seen from them (Nayayan, R., Black Holes in Astrophysics, New J. Phys., 7, 199-218, 2005). It is pointed out…
We show that an extremal Gibbons-Maeda-Garfinkle-Horowitz-Strominger black hole may act as a particle accelerator with arbitrarily high energy when two uncharged particles falling freely from rest to infinity on the near horizon. We show…
The radiation emitted by horizonless exotic compact objects (ECOs), such as wormholes, 2-2-holes, fuzzballs, gravastars, boson stars, collapsed polymers, superspinars etc., is expected to be strongly suppressed when compared to the…
Highly magnetised rapidly spinning neutron stars are widely considered to be natural sites for acceleration of charged particles. Powerful acceleration mechanism due to unipolar induction is thought to operate in the magnetospheres of…
Some general features of cosmic ray acceleration are summarized along with some inferences that can be drawn concerning the origin of the UHE component. The UHE luminosity density is found to be similar to that derived for GeV cosmic rays…
We discuss that in the extreme relativistic limit, i.e., when z >>1, where z is the surface gravitational redshift, there could be radiation pressure supported and dominated stars with arbitrary gravitational mass, high or low. Such Objects…
One of the most important issues in relativistic astrophysics is to explain the origin mechanisms of (ultra)high energy charged particle components of cosmic rays. Black holes (BHs) being huge reservoirs of (gravitational) energy can be…