相关论文: Comment on "Observing a wormhole"

We consider wormhole geometries subject to a gravitational action consisting of non-linear powers of the Ricci scalar. Specifically, wormhole throats are studied in the case where Einstein gravity is supplemented with a Ricci-squared and…

Motion of short-period stars orbiting the supermassive black hole in our Galactic Center has been monitored for more than 20 years. These observations are currently offering a new way to test the gravitational theory in an unexplored…

We study in detail gravitational lensing caused by a supermassive fermion star and compare it with lensing by a black hole of the same mass. It is argued that lensing effects, being very distinct, may shed some light on the yet unexplained…

It has been shown that a noncommutative-geometry background may be able to support traversable wormholes. This paper discusses the possible detection of such wormholes in the outer regions of galactic halos by means of gravitational…

The existence of cosmological compact objects with very strong gravity is a prediction of General Relativity and an exact solution of the Einstein equations. These objects are called black holes and recently we had the first observations of…

Black and white holes play remarkably contrasting roles in general relativity versus observational astrophysics. While there is overwhelming observational evidence for the existence of compact objects that are "cold, dark, and heavy", which…

While the event horizon of a black hole could cast a shadow that was observed recently, a central singularity without horizon could also give rise to such a feature. This leaves us with a question on the nature of the supermassive black…

Recent measurements, of the velocities of stars near the center of the Milky Way have provided the strongest evidence for the presence of a supermassive black hole in a galaxy, but the observational uncertainties poorly constrain many of…

The spin of a black hole retains the memory of how the black hole grew, and can be a potent source of energy for powering relativistic jets. To understand the diagnostic power and astrophysical significance of black hole spin, however, we…

It has been well known that in the point of view of a distant observer, all in-falling matter to a black hole (BH) will be eventually stalled and "frozen" just outside the event horizon of the BH, although an in-falling observer will see…

I discuss several general-relativistic effects that are likely to be of interest in the astrophysics of black holes and neutron stars

We study the effects of neutrino lensing induced by a Damour-Solodukhin wormhole on the neutrino oscillation. We derive and calculate the flavour transition probabilities in the presence of Damour-Solodukhin factor $\Lambda$ as a shift in…

We study the linear polarization from the accretion disk around a class of static traversable wormholes. Applying the simplified model of a magnetized fluid ring orbiting in the equatorial plane, we search for characteristic signatures,…

The S-star cluster in the Galactic center allows us to study the physics close to a supermassive black hole, including distinctive dynamical tests of general relativity. Our best estimates for the mass of and the distance to Sgr A* using…

We analytically explore the effect of falling matter on a spherically symmetric wormhole supported by a spherical shell composed of exotic matter located at its throat. The falling matter is assumed to be also a thin spherical shell…

Recently wide publicity has been given to a claim by T. Vachaspati that "black holes do not exist", that the objects known as black holes in astrophysics should rather be called "black stars" and they not only do not have event horizons but…

Assuming that spacetime tunnels -wormholes and ringholes- naturally exist in the universe, we investigate the conditions making them embeddible in Friedmann space, and the possible observable effects of these tunnels, including: lensing and…

We investigate gravitational lensing by a primary photon sphere which is a sphere filled with unstable circular light orbits, and by a secondary photon sphere on a wormhole throat in a black-bounce spacetime which is suggested in [F. S. N.…

Black hole lensing and gravitational waves are, respectively, closely dependent of the property of the lens and radiation source. In this letter, a universal relation between them is established for a rotating black hole acting…

We consider a technique of calculating deflection of the light passing through wormholes (from one universe to another). We find fundamental and characteristic features of electromagnetic radiation passing through the wormholes. Making use…