相关论文: Compact objects as the catalysts for vacuum decays
A Buchdahl star is a highly compact star for which the boundary radius $R$ obeys $R=\frac98 r_+$, where $r_+$ is the gravitational radius of the star itself. A quasiblack hole is a maximum compact star, or more generically a maximum compact…
We consider a black hole accreting spherically from the surrounding medium. If accretion produces a luminosity close to the Eddington limit the hole acquires a net charge so that electrons and ions can fall with the same velocity. The…
Black holes are the densest form of energy, and in the presence of compact dimensions black objects may take one of several forms including the black-hole and the black-string, the simplest relevant background being R^{3+1} * S^1. Recent…
The possible detection of echoes in late gravitational-wave signals is the most promising way to test horizonless alternatives to general relativistic black holes, and probe the physics of these hypothetical ultra-compact objects. While…
Many lines of evidence suggest that nonbaryonic dark matter constitutes roughly 30% of the critical closure density, but the composition of this dark matter is unknown. One class of candidates for the dark matter is compact objects formed…
Recently, in the series of works a new effect of acceleration of particles by black holes was found. Under certain conditions, the energy in the centre of mass frame can become infinitely large. The essential ingredient of such effect is…
We consider the quantum vacuum effects of the massless scalar fields that are non-minimally coupled to the background geometry of a collapsing homogeneous ball of dust. It is shown that for a definite range of coupling constants, there are…
We examine the effect of large extra dimensions on black hole seeded vacuum decay using the Randall-Sundrum model as a prototype for warped extra dimensions. We model the braneworld black hole by a tidal solution, and solve the Higgs…
Astrophysical compact objects are studied in the context of quadratic non-metricity gravity. The solutions to the gravitational field equations, which include fluid components, are analyzed to investigate the density and pressure properties…
A generic feature of nearly out-of-equilibrium dissipative systems is that they resonate through a set of quasinormal modes. Black holes - the absorbing objects par excellence - are no exception. When formed in a merger, black holes vibrate…
The origin of the observed acceleration of the expansion of the universe is a major problem of modern cosmology and theoretical physics. Simple estimations of the contribution of vacuum to the density energy of the universe in quantum field…
We define compactness of a gravitational lens as the scaled closest distance of approach (i.e., $r_0/M$) of the null geodesic giving rise to an image. We model forty supermassive dark objects as Schwarzschild lenses and compute compactness…
In the dark energy star picture a compact object is transparent at radio and optical frequencies, and acts as a defocusing lens. Thus the object itself appears as a luminous disk whose surface brightness reflects the surface brightness of…
Very compact objects probe extreme gravitational fields and may be the key to understand outstanding puzzles in fundamental physics. These include the nature of dark matter, the fate of spacetime singularities, or the loss of unitarity in…
False vacuum states are metastable in quantum field theories, and true vacuum bubbles can be nucleated due to the quantum tunneling effect. It was recently suggested that an evaporating black hole (BH) can be a catalyst of bubble…
To account for the microlensing events observed in the Galactic halo, Gurevich, Zybin, and Sirota have proposed a model of gravitationally bound, noncompact objects with masses of 0.01-1M_\odot. These objects are formed in the expanding…
A foundational theorem due to Buchdahl states that, within General Relativity (GR), the maximum compactness $\mathcal{C}\equiv GM/(Rc^2)$ of a static, spherically symmetric, perfect fluid object of mass $M$ and radius $R$ is…
Separate regions in space are generally entangled, even in the vacuum state. It is known that this entanglement can be swapped to separated Unruh-DeWitt detectors, i.e., that the vacuum can serve as a source of entanglement. Here, we…
An important feature of Schwarzschild spacetime is the presence of orbiting null geodesics and caustics. Their presence implies strong gravitational lensing effects for matter and radiation, i.e., for excitations of quantum fields. Here, we…
Horizonless spacetimes describing spatially regular ultra-compact objects which, like black-hole spacetimes, possess closed null circular geodesics (light rings) have recently attracted much attention from physicists and mathematicians. In…