The belief still persists, at least for an important part of the community, that in general relat... more The belief still persists, at least for an important part of the community, that in general relativity the cosmological constant $$\Lambda $$ Λ must remain immaculate. However, Bianchi identities show that $$\Lambda $$ Λ could acquire local properties in the presence of matter, i.e., $$\Lambda \rightarrow \,\Lambda (x^\mu )$$ Λ → Λ ( x μ ) . In this paper we go even further, and we show that a non-uniform vacuum energy does not even require coexistence with any additional form of matter-energy, nor of any theory beyond general relativity, at least for extreme environments, such as the proximity of a black hole.
We present a simple, analytic and straightforward method to elucidate the effects produced by pol... more We present a simple, analytic and straightforward method to elucidate the effects produced by polytropic fluids on any other gravitational source, no matter its nature, for static and spherically symmetric spacetimes. As a direct application, we study the interaction between polytropes and perfect fluids coexisting inside a self-gravitating stellar object.
We review the basic elements of the Minimal Geometric Deformation approach in detail. This method... more We review the basic elements of the Minimal Geometric Deformation approach in detail. This method has been successfully used to generate brane-world configurations from general relativistic perfect fluid solutions.
General Relativity (GR) in its century of existence represents, without a doubt, one of the most ... more General Relativity (GR) in its century of existence represents, without a doubt, one of the most important achievements of human knowledge. The predictions made by this theory, like the perihelion shift of Mercury, light deflection and gravitational lensing, the gravitational redshift and time delay, black holes and gravitational waves—just to mention some of the most remarkable ones, have given it the honours which deserves as one of the fundamental theories of Physics (for a recent review on experimental tests of GR see [1] and references therein).
There are general arguments based on quantum physics supporting the idea that classical black hol... more There are general arguments based on quantum physics supporting the idea that classical black holes of the kind predicted by GR can only exist with a mass significantly larger than the Planck scale \({M_{\text {P}}}=\sqrt{\hbar {c/G} _\mathrm{N}}\) (where c is the speed of light, \(G_\mathrm{N}\) is again Newton’s constant and \(\hbar \) the reduced Planck constant).
We have seen that the new terms in the effective four-dimensional Einstein field equations ( 1.14... more We have seen that the new terms in the effective four-dimensional Einstein field equations ( 1.14) originating from the bulk, which can be viewed as corrections to GR, might be the key to solve some open issues in gravity, like the dark matter problem.
We employ the gravitational decoupling approach for static and spherically symmetric systems to d... more We employ the gravitational decoupling approach for static and spherically symmetric systems to develop a simple and powerful method in order to (a) continuously isotropize any anisotropic solution of the Einstein field equations, and (b) generate new solutions for self-gravitating distributions with the same or vanishing complexity factor. A few working examples are given for illustrative purposes.
The minimal geometric deformation approach is employed to show the existence of brane-world stell... more The minimal geometric deformation approach is employed to show the existence of brane-world stellar distributions with vacuum Schwarzschild exterior, thus without energy leaking from the exterior of the brane-world star into the extra dimension. The interior satisfies all elementary criteria of physical acceptability for a stellar solution, namely, it is regular at the origin, the pressure and density are positive and decrease monotonically with increasing radius, finally all energy conditions are fulfilled. A very thin solid crust with negative radial pressure separates the interior from the exterior, having a thickness Δ inversely proportional to both the brane tension σ and the radius R of the star, i.e. Δ ^-1∼ R σ . This brane-world star with Schwarzschild exterior would appear only thermally radiating to a distant observer and be fully compatible with the stringent constraints imposed on stellar parameters by observations of gravitational lensing, orbital evolutions or properti...
We consider a solution of the effective four-dimensional brane-world equations, obtained from the... more We consider a solution of the effective four-dimensional brane-world equations, obtained from the General Relativistic Schwarzschild metric via the principle of Minimal Geometric Deformation, and investigate the corresponding signatures stemming from the possible existence of a warped extra dimension. In particular, we derive bounds on an extra-dimensional parameter, closely related with the fundamental gravitational length, from the experimental results of the classical tests of General Relativity in the Solar system.
The belief still persists, at least for an important part of the community, that in general relat... more The belief still persists, at least for an important part of the community, that in general relativity the cosmological constant $$\Lambda $$ Λ must remain immaculate. However, Bianchi identities show that $$\Lambda $$ Λ could acquire local properties in the presence of matter, i.e., $$\Lambda \rightarrow \,\Lambda (x^\mu )$$ Λ → Λ ( x μ ) . In this paper we go even further, and we show that a non-uniform vacuum energy does not even require coexistence with any additional form of matter-energy, nor of any theory beyond general relativity, at least for extreme environments, such as the proximity of a black hole.
We present a simple, analytic and straightforward method to elucidate the effects produced by pol... more We present a simple, analytic and straightforward method to elucidate the effects produced by polytropic fluids on any other gravitational source, no matter its nature, for static and spherically symmetric spacetimes. As a direct application, we study the interaction between polytropes and perfect fluids coexisting inside a self-gravitating stellar object.
We review the basic elements of the Minimal Geometric Deformation approach in detail. This method... more We review the basic elements of the Minimal Geometric Deformation approach in detail. This method has been successfully used to generate brane-world configurations from general relativistic perfect fluid solutions.
General Relativity (GR) in its century of existence represents, without a doubt, one of the most ... more General Relativity (GR) in its century of existence represents, without a doubt, one of the most important achievements of human knowledge. The predictions made by this theory, like the perihelion shift of Mercury, light deflection and gravitational lensing, the gravitational redshift and time delay, black holes and gravitational waves—just to mention some of the most remarkable ones, have given it the honours which deserves as one of the fundamental theories of Physics (for a recent review on experimental tests of GR see [1] and references therein).
There are general arguments based on quantum physics supporting the idea that classical black hol... more There are general arguments based on quantum physics supporting the idea that classical black holes of the kind predicted by GR can only exist with a mass significantly larger than the Planck scale \({M_{\text {P}}}=\sqrt{\hbar {c/G} _\mathrm{N}}\) (where c is the speed of light, \(G_\mathrm{N}\) is again Newton’s constant and \(\hbar \) the reduced Planck constant).
We have seen that the new terms in the effective four-dimensional Einstein field equations ( 1.14... more We have seen that the new terms in the effective four-dimensional Einstein field equations ( 1.14) originating from the bulk, which can be viewed as corrections to GR, might be the key to solve some open issues in gravity, like the dark matter problem.
We employ the gravitational decoupling approach for static and spherically symmetric systems to d... more We employ the gravitational decoupling approach for static and spherically symmetric systems to develop a simple and powerful method in order to (a) continuously isotropize any anisotropic solution of the Einstein field equations, and (b) generate new solutions for self-gravitating distributions with the same or vanishing complexity factor. A few working examples are given for illustrative purposes.
The minimal geometric deformation approach is employed to show the existence of brane-world stell... more The minimal geometric deformation approach is employed to show the existence of brane-world stellar distributions with vacuum Schwarzschild exterior, thus without energy leaking from the exterior of the brane-world star into the extra dimension. The interior satisfies all elementary criteria of physical acceptability for a stellar solution, namely, it is regular at the origin, the pressure and density are positive and decrease monotonically with increasing radius, finally all energy conditions are fulfilled. A very thin solid crust with negative radial pressure separates the interior from the exterior, having a thickness Δ inversely proportional to both the brane tension σ and the radius R of the star, i.e. Δ ^-1∼ R σ . This brane-world star with Schwarzschild exterior would appear only thermally radiating to a distant observer and be fully compatible with the stringent constraints imposed on stellar parameters by observations of gravitational lensing, orbital evolutions or properti...
We consider a solution of the effective four-dimensional brane-world equations, obtained from the... more We consider a solution of the effective four-dimensional brane-world equations, obtained from the General Relativistic Schwarzschild metric via the principle of Minimal Geometric Deformation, and investigate the corresponding signatures stemming from the possible existence of a warped extra dimension. In particular, we derive bounds on an extra-dimensional parameter, closely related with the fundamental gravitational length, from the experimental results of the classical tests of General Relativity in the Solar system.
We show the first simple, systematic and direct approach to decoupling gravitational sources in g... more We show the first simple, systematic and direct approach to decoupling gravitational sources in general relativity. As a direct application, a robust and simple way to generate anisotropic solutions for self-gravitating systems from perfect fluid solutions is presented.
Uploads
Papers