Jorge Rueda - Academia.edu (original) (raw)
Papers by Jorge Rueda
SGR 0418+5729 is a "Rosetta Stone" for deciphering the energy source of Soft Gamma Ray Repeaters ... more SGR 0418+5729 is a "Rosetta Stone" for deciphering the energy source of Soft Gamma Ray Repeaters (SGRs) and Anomalous X-ray Pulsars (AXPs). We show a model based on canonical physics and astrophysics for SGRs and AXPs powered by massive highly magnetized rotating white dwarfs (WDs), in total analogy with pulsars powered by rotating neutron stars (NSs). We predict for SGR 0418+5729 a lower limit for its spin-down rate, dotPgeqLXP3/(4pi2I)=1.18times10−16\dot{P} \geq L_X P^3/(4\pi^2 I)=1.18\times 10^{-16}dotPgeqLXP3/(4pi2I)=1.18times10−16 where III is the moment of inertia of the WD. We show for SGRs and AXPs that, the occurrence of the glitch and the gain of rotational energy, is due to the release of gravitational energy associated to the contraction and decrease of the moment of inertia of the WDs. The steady emission and the outburst following the glitch are explained by the loss of rotational energy of the Wds, in view of the much larger moment of inertia of the WDs, as compared to the one of NSs and/or quark stars. There is no need here to invoke the unorthodox concept of magnetic energy release due to decay of overcritical magnetic fields, as assumed in the magnetar model. A new astrophysical scenario for the SGRs and AXPs associated to Supernova remnants is presented. The observational campaigns of the X-ray Japanese satellite Suzaku on AE Aquarii and the corresponding theoretical works by Japanese groups and recent results of the Hubble Space Telescope, give crucial information for our theoretical model. Follow-on missions of Hubble Telescope and VLT are highly recommended to give further observational evidence of this most fundamental issue of relativistic astrophysics: the identification of the true SGRs/AXPs energy source.
We investigate the distribution of dark matter in galaxies by solving the equations of equilibriu... more We investigate the distribution of dark matter in galaxies by solving the equations of equilibrium of a self-gravitating system of massive fermions (`inos') at selected temperatures and degeneracy parameters within general relativity. Our most general solutions show, as a function of the radius, a segregation of three physical regimes: 1) an inner core of almost constant density governed by degenerate quantum statistics; 2) an intermediate region with a sharply decreasing density distribution followed by an extended plateau, implying quantum corrections; 3) an asymptotic, rhoproptor−2\rho\propto r^{-2}rhoproptor−2 classical Boltzmann regime fulfilling, as an eigenvalue problem, a fixed value of the flat rotation curves. This eigenvalue problem determines, for each value of the central degeneracy parameter, the mass of the ino as well as the radius and mass of the inner quantum core. Consequences of this alternative approach to the central and halo regions of galaxies, ranging from dwarf to big spirals, for SgrA*, as well as for the existing estimates of the ino mass, are outlined.
The recent observations of SGR 0418+5729 with a rotational period of P = 9.04 s, an upper limit o... more The recent observations of SGR 0418+5729 with a rotational period of P = 9.04 s, an upper limit of the first time derivative of the rotational periodṖ < 6.0 × 10 −15 , and an X-ray luminosity of L X = 6.2 × 10 31 erg/s [1] offer an authentic Rosetta Stone for deciphering the energy source of SGRs and AXPs. The "magnetar" model, appeals to a yet untested new energy source in astrophysical systems: a primary energy source due to bulk magnetic energy. It leads for SGR 0418+5729 to results in contradiction with observations. Our aim is to show how a consistent model for SGRs and AXPs can be expressed in terms of canonical physics and astrophysics within massive, fast rotating, and highly magnetized white dwarfs . The energetics of SGRs and AXPs, including their outburst activities can be well explained through the change of rotational energy of the white dwarf, associated to the observed glitches, the sudden changes of the rotational period. In addition, we evidence that the sources PSR J1846-0258 with P = 0.3 s, SGR 1627-41 with P = 2.59 s, 1E 1547.0-5408 with P = 2.07 s as well as PSR J1622-4950 with P = 4.33 s, traditionally indicated as magnetar candidates, can be indeed interpreted as ordinary neutron stars. Their rotational periods are below the limit of stability P ∼ 5 s for uniformly rotating carbon white dwarfs; their steady X-ray luminosity can be well explained within the neutron star model, and their magnetic fields are close to the ones of some known radio pulsars. Excluding these sources, we find for all the other sources traditionally indicated as magnetar candidates, a consistent model based on rotating white dwarfs. Their surface dipole magnetic fields are comprised in the range 7.5 × 10 8 G B
In our previous treatment of neutron stars, we have developed the model fulfilling global and not... more In our previous treatment of neutron stars, we have developed the model fulfilling global and not local charge neutrality. In order to implement such a model, we have shown the essential role by the Thomas-Fermi equations, duly generalized to the case of electromagnetic field equations in a general relativistic framework, forming a coupled system of equations that we have denominated Einstein-Maxwell-Thomas-Fermi (EMTF) equations. From the microphysical point of view, the weak interactions are accounted for by requesting the \beta\ stability of the system, and the strong interactions by using the \sigma-\omega-\rho\ nuclear model, where \sigma, \omega\ and \rho\ are the mediator massive vector mesons. Here we examine the equilibrium configurations of slowly rotating neutron stars by using the Hartle formalism in the case of the EMTF equations indicated above. We integrate these equations of equilibrium for different central densities and circular angular velocities and compute the mass, polar and equatorial radii, angular momentum, eccentricity, moment of inertia, as well as quadrupole moment of the configurations. Both the Keplerian mass-shedding limit and the axisymmetric secular instability are used to construct the new mass-radius relation. We compute the maximum and minimum masses and rotation frequencies of neutron stars. We compare and contrast all the results for the global and local charge neutrality cases.
We have recently proved the impossibility of imposing the condition of local charge neutrality in... more We have recently proved the impossibility of imposing the condition of local charge neutrality in a self-gravitating system of degenerate neutrons, protons and electrons in beta\betabeta-equilibrium. The coupled system of the general relativistic Thomas-Fermi equations and the Einstein-Maxwell equations have been shown to supersede the traditional Tolman-Oppenheimer-Volkoff equations. Here we present the Newtonian limit of the new equilibrium equations. We also extend the treatment to the case of finite temperatures and finally we give the explicit demonstration of the constancy of the Klein potentials in the case of finite temperatures generalizing the condition of constancy of the general relativistic Fermi energies in the case of zero temperatures.
On the dyadotorus
Aps Meeting Abstracts, Apr 1, 2008
The ``dyadotorus'' is defined as the region around a Kerr-Newman black hole where pair creation b... more The ``dyadotorus'' is defined as the region around a Kerr-Newman black hole where pair creation by vacuum polarization occurs. This concept extends to the case of stationary geometries the concept of ``dyadosphere'' already introduced in the static case in the Reissner-Nordstrom geometry. The energetics of the dyadotorii, their topology and embedding diagrams are compared and contrasted to the ones of the black hole.
It has been shown recently that taking into account strong, weak, electromagnetic, and gravitatio... more It has been shown recently that taking into account strong, weak, electromagnetic, and gravitational interactions, and fulfilling the global charge neutrality of the system, a transition layer will happen between the core and crust of neutron stars, at the nuclear saturation density. We use relativistic mean field theory together with the Thomas-Fermi approximation to study the detailed structure of this transition layer and calculate its surface and Coulomb energy. We find that the surface tension is proportional to a power-law function of the baryon number density in the core bulk region. We also analyze the influence of the electron component and the gravitational field on the structure of the transition layer and the value of the surface tension to compare and contrast with known phenomenological results in nuclear physics. Based on the above results we study the instability against Bohr-Wheeler surface deformations in the case of neutron stars obeying global charge neutrality. Assuming the core-crust transition at nuclear density ρ core ≈ 2.7 × 10 14 g cm −3 , we find that the instability sets the upper limit to the crust density, ρ crit crust ≈ 1.2 × 10 14 g cm −3 . This result implies a nonzero lower limit to the maximum electric field of the core-crust transition surface and makes inaccessible a limit of quasilocal charge neutrality in the limit ρ crust = ρ core . The general framework presented here can be also applied to study the stability of sharp phase transitions in hybrid stars as well as in strange stars, both bare and with outer crust. The results of this work open the way to a more general analysis of the stability of these transition surfaces, accounting for other effects such as gravitational binding, centrifugal repulsion, magnetic field induced by rotating electric field, and therefore magnetic dipole-dipole interactions.
Relativistic Thomas-Fermi treatment of compressed atoms and compressed nuclear matter cores of stellar dimensions
Phys Rev C, 2011
The Feynman-Metropolis-Teller treatment of compressed atoms is extended to the relativistic regim... more The Feynman-Metropolis-Teller treatment of compressed atoms is extended to the relativistic regimes. Each atomic configuration is confined by a Wigner-Seitz cell and is characterized by a positive electron Fermi energy. The nonrelativistic treatment assumes a pointlike nucleus and infinite values of the electron Fermi energy can be attained. In the relativistic treatment there exists a limiting configuration, reached when the Wigner-Seitz cell radius equals the radius of the nucleus, with a maximum value of the electron Fermi energy (EeF)max, here expressed analytically in the ultrarelativistic approximation. The corrections given by the relativistic Thomas-Fermi-Dirac exchange term are also evaluated and shown to be generally small and negligible in the relativistic high-density regime. The dependence of the relativistic electron Fermi energies by compression for selected nuclei are compared and contrasted to the nonrelativistic ones and to the ones obtained in the uniform approximation. The relativistic Feynman-Metropolis-Teller approach here presented overcomes some difficulties in the Salpeter approximation generally adopted for compressed matter in physics and astrophysics. The treatment is then extrapolated to compressed nuclear matter cores of stellar dimensions with A≃(mPlanck/mn)3~1057 or Mcore~M⊙. A new family of equilibrium configurations exists for selected values of the electron Fermi energy varying in the range 0<EeF⩽(EeF)max. Such configurations fulfill global but not local charge neutrality. They have electric fields on the core surface, increasing for decreasing values of the electron Fermi energy reaching values much larger than the critical value Ec=me2c3/(eℏ) for EeF=0. We compare and contrast our results with the ones of Thomas-Fermi model in strange stars.
On the electrodynamics properties of nuclear matter cores
It is by now clear that Gamma ray Bursts originate from an electron positron plasma formed during... more It is by now clear that Gamma ray Bursts originate from an electron positron plasma formed during the process of gravitational collapse to a Black Hole. It is crucial to identify the initial conditions in the neutron star core originating such a collapse which give origin to the vast electrodynamics process originating such an electron positron plasma during the late phases of the collapse as the horizon of the Black Hole is reached. We present a new approach, based on a ultra-relativistic Thomas-Fermi approach, to the nuclear matter in bulk enforcing the condition of global charge neutrality as opposed to the local charge neutrality usually imposed. A new ground state is found that can differ by 1049 ergs from the ones where local charge neutrality is implemented. Electric fields close to the critical value can exist at the surface of the core at the onset of the gravitational instability. We outline consequences of these results in nuclear physics, in the formation process of neutron stars and the supernovae emission in the X and Gamma rays as well as possibly in the process of ejection of the remnant.
Moment of inertia, radii, surface emission from a new theoretical understanding of Neutron Stars
We formulate the equations of neutron stars taking into account the strong, weak, electromagnetic... more We formulate the equations of neutron stars taking into account the strong, weak, electromagnetic and gravitational interactions within a new fully general relativistic Thomas-Fermi approach. The nuclear interactions are described by the exchange of the sigma, omega, and rho virtual mesons. The constancy of the generalized chemical potential, for short Klein potentials, of the particle species is required as a condition of equilibrium throughout the star. The continuity of the Klein potentials in the transition from the core to the crust imposes the presence of a strong electric field larger than the critical one for vacuum polarization. Correspondingly, the electron density decreases in the core-crust transition region. Such a phenomenon leads to neutron stars with crusts with masses and thickness smaller with respect to the ones of traditional neutron star configurations that satisfy local charge neutrality from the center all the way up to the surface. We present new estimates of...
The Thirteenth Marcel Grossmann Meeting, 2014
We describe one of the so-called low magnetic field magnetars SGR 0418+5729, as a massive fast ro... more We describe one of the so-called low magnetic field magnetars SGR 0418+5729, as a massive fast rotating highly magnetized white dwarf following Malheiro et. al. We give bounds for the mass, radius, moment of inertia, and magnetic field for these sources, by requesting the stability of realistic general relativistic uniformly rotating configurations. Based on these parameters, we improve the theoretical prediction of the lower limit of the spin-down rate of SGR 0418+5729. In addition, we compute the electron cyclotron frequencies corresponding to the predicted surface magnetic fields.
A general relativistic Thomas-Fermi treatment of neutron star cores
ABSTRACT We formulate the set of self-consistent ground-state equilibrium equations of a system o... more ABSTRACT We formulate the set of self-consistent ground-state equilibrium equations of a system of degenerate neutrons, protons and electrons in beta equilibrium taking into account quantum statistics, electro-weak, and strong interactions, within the framework of general relativity. The strong interaction between nucleons is modeled through sigma-omega-rho meson exchange in the context of the extended Walecka model, all duly expressed in general relativity. We demonstrate that, as in the non-interacting case, the thermodynamic equilibrium condition given by the constancy of the Fermi energy of each particle-specie can be properly generalized to include the contribution of all fields.
Extracting multipole moments of neutron stars from quasi-periodic oscillations in low mass X-ray binaries
Astronomy Reports, 2015
A New Family of Neutron Star Models: Global Neutrality Versus Local Neutrality
The Twelfth Marcel Grossmann Meeting - On Recent Developments in Theoretical and Experimental General Relativity Astrophysics and Relativistic Field Theories - Proceedings of the MG12 Meeting on General Relativity, 2012
ABSTRACT We formulate the set of self-consistent ground-state equilibrium equations of a system o... more ABSTRACT We formulate the set of self-consistent ground-state equilibrium equations of a system of degenerate neutrons, protons and electrons in beta equilibrium taking into account quantum statistics and electro-weak interactions within the framework of general relativity. We point out the existence of globally neutral neutron star configurations in contrast with the traditional locally neutral ones. We discuss new gravito-electrodynamic effects present in such globally neutral neutron star equilibrium configurations.
From Compressed Atoms to Compressed Massive Nuclear Density Cores
The Twelfth Marcel Grossmann Meeting - On Recent Developments in Theoretical and Experimental General Relativity Astrophysics and Relativistic Field Theories - Proceedings of the MG12 Meeting on General Relativity, 2012
On Degenerate Compressed Atoms and Compressed Nuclear Matter Cores of Stellar Dimensions
International Journal of Modern Physics: Conference Series, 2012
ABSTRACT The relativistic generalization of the Feynman, Metropolis and Teller treatment of compr... more ABSTRACT The relativistic generalization of the Feynman, Metropolis and Teller treatment of compressed atoms is obtained. Each atomic configuration is confined by a Wigner-Seitz cell and is characterized by a positive electron Fermi energy. There exists a limiting configuration, reached when the Wigner-Seitz cell radius equals the radius of the nucleus, with a maximum value of the electron Fermi energy (EeF)max, here expressed analytically in the ultra-relativistic approximation. The treatment is then extrapolated to compressed nuclear matter cores of stellar dimensions with A ≃ (mPlanck/mn)3 1057 or Mcore M⊙. A new family of equilibrium configurations exists for selected values of the electron Fermi energy varying in the range 0 < EeF <= (EeF)max. Such configurations fulfill global but not local charge neutrality. They have electric fields on the core surface, increasing for decreasing values of the electron Fermi energy reaching values much larger than the critical value Ec = me2c^3/(e\hbar ), for EeF = 0.
EAS Publications Series, 2013
The possibility to divide GRBs in different subclasses allow to understand better the physics und... more The possibility to divide GRBs in different subclasses allow to understand better the physics underlying their emission mechanisms and progenitors. The induced gravitational collapse scenario proposes a binary progenitor to explain the time-sequence in GRBs-SNe. We show the existence of a common behavior of the late decay of the Xray afterglow emission of this subclass of GRBs, pointing to a common physical mechanism of their late emission, consistent with the IGC picture.
Gravitation and Cosmology, 2014
In light of the relativistic precession model, we present here detailed analyses, extending the o... more In light of the relativistic precession model, we present here detailed analyses, extending the ones performed in the Schwarzschild and Kerr spacetimes. We consider the kilohertz quasi-periodic oscillations in the Hartle-Thorne spacetime, which describes the gravitational field of a rotating and deformed object. We derive the analytic formulas for the epicyclic frequencies in the Hartel-Thorne spacetime and by means of these frequencies we interpret the kilohertz quasi-periodic oscillations of low-mass X-ray binaries of the atoll and Z -sources, on the basis of the relativistic precession model. Particularly we perform analyzes for Z -source: GX 5-1. We show that the quasi-periodic oscillations data can provide information on the parameters, namely, the mass, angular momentum and quadrupole moment of the compact objects in the low-mass X-ray binaries.
Massive, highly magnetized white dwarfs with fields up to 10 9 G have been observed and theoretic... more Massive, highly magnetized white dwarfs with fields up to 10 9 G have been observed and theoretically used for the description of a variety of astrophysical phenomena. Ultramagnetized white dwarfs with uniform interior fields up to 10 18 G have been recently purported to obey a new maximum mass limit, M max ≈ 2.58 M , which largely overcomes the traditional Chandrasekhar value, M Ch ≈ 1.44 M . Such a larger limit would make these astrophysical objects viable candidates for the explanation of the superluminous population of Type Ia supernovae. We show that several macro and micro physical aspects such as gravitational, dynamical stability, breaking of spherical symmetry, general relativity, inverse β decay, and pycnonuclear fusion reactions are of most relevance for the self-consistent description of the structure and assessment of stability of these objects. It is shown in this work that the first family of magnetized white dwarfs indeed satisfy all the criteria of stability, while the ultramagnetized white dwarfs are very unlikely to exist in nature since they violate minimal requests of stability. Therefore, the canonical Chandrasekhar mass limit of white dwarfs still has to be applied.
International Journal of Modern Physics E, 2011
The properties of uniformly rotating white dwarfs are analyzed within the framework of general re... more The properties of uniformly rotating white dwarfs are analyzed within the framework of general relativity. Hartle's formalism is applied to construct self-consistently the internal and external solutions to the Einstein equations. The mass, the radius, the moment of inertia and quadrupole moment of rotating white dwarfs have been calculated as a function of both the central density and rotation period of the star. The maximum mass of rotating white dwarfs for stable configurations has been obtained.
SGR 0418+5729 is a "Rosetta Stone" for deciphering the energy source of Soft Gamma Ray Repeaters ... more SGR 0418+5729 is a "Rosetta Stone" for deciphering the energy source of Soft Gamma Ray Repeaters (SGRs) and Anomalous X-ray Pulsars (AXPs). We show a model based on canonical physics and astrophysics for SGRs and AXPs powered by massive highly magnetized rotating white dwarfs (WDs), in total analogy with pulsars powered by rotating neutron stars (NSs). We predict for SGR 0418+5729 a lower limit for its spin-down rate, dotPgeqLXP3/(4pi2I)=1.18times10−16\dot{P} \geq L_X P^3/(4\pi^2 I)=1.18\times 10^{-16}dotPgeqLXP3/(4pi2I)=1.18times10−16 where III is the moment of inertia of the WD. We show for SGRs and AXPs that, the occurrence of the glitch and the gain of rotational energy, is due to the release of gravitational energy associated to the contraction and decrease of the moment of inertia of the WDs. The steady emission and the outburst following the glitch are explained by the loss of rotational energy of the Wds, in view of the much larger moment of inertia of the WDs, as compared to the one of NSs and/or quark stars. There is no need here to invoke the unorthodox concept of magnetic energy release due to decay of overcritical magnetic fields, as assumed in the magnetar model. A new astrophysical scenario for the SGRs and AXPs associated to Supernova remnants is presented. The observational campaigns of the X-ray Japanese satellite Suzaku on AE Aquarii and the corresponding theoretical works by Japanese groups and recent results of the Hubble Space Telescope, give crucial information for our theoretical model. Follow-on missions of Hubble Telescope and VLT are highly recommended to give further observational evidence of this most fundamental issue of relativistic astrophysics: the identification of the true SGRs/AXPs energy source.
We investigate the distribution of dark matter in galaxies by solving the equations of equilibriu... more We investigate the distribution of dark matter in galaxies by solving the equations of equilibrium of a self-gravitating system of massive fermions (`inos') at selected temperatures and degeneracy parameters within general relativity. Our most general solutions show, as a function of the radius, a segregation of three physical regimes: 1) an inner core of almost constant density governed by degenerate quantum statistics; 2) an intermediate region with a sharply decreasing density distribution followed by an extended plateau, implying quantum corrections; 3) an asymptotic, rhoproptor−2\rho\propto r^{-2}rhoproptor−2 classical Boltzmann regime fulfilling, as an eigenvalue problem, a fixed value of the flat rotation curves. This eigenvalue problem determines, for each value of the central degeneracy parameter, the mass of the ino as well as the radius and mass of the inner quantum core. Consequences of this alternative approach to the central and halo regions of galaxies, ranging from dwarf to big spirals, for SgrA*, as well as for the existing estimates of the ino mass, are outlined.
The recent observations of SGR 0418+5729 with a rotational period of P = 9.04 s, an upper limit o... more The recent observations of SGR 0418+5729 with a rotational period of P = 9.04 s, an upper limit of the first time derivative of the rotational periodṖ < 6.0 × 10 −15 , and an X-ray luminosity of L X = 6.2 × 10 31 erg/s [1] offer an authentic Rosetta Stone for deciphering the energy source of SGRs and AXPs. The "magnetar" model, appeals to a yet untested new energy source in astrophysical systems: a primary energy source due to bulk magnetic energy. It leads for SGR 0418+5729 to results in contradiction with observations. Our aim is to show how a consistent model for SGRs and AXPs can be expressed in terms of canonical physics and astrophysics within massive, fast rotating, and highly magnetized white dwarfs . The energetics of SGRs and AXPs, including their outburst activities can be well explained through the change of rotational energy of the white dwarf, associated to the observed glitches, the sudden changes of the rotational period. In addition, we evidence that the sources PSR J1846-0258 with P = 0.3 s, SGR 1627-41 with P = 2.59 s, 1E 1547.0-5408 with P = 2.07 s as well as PSR J1622-4950 with P = 4.33 s, traditionally indicated as magnetar candidates, can be indeed interpreted as ordinary neutron stars. Their rotational periods are below the limit of stability P ∼ 5 s for uniformly rotating carbon white dwarfs; their steady X-ray luminosity can be well explained within the neutron star model, and their magnetic fields are close to the ones of some known radio pulsars. Excluding these sources, we find for all the other sources traditionally indicated as magnetar candidates, a consistent model based on rotating white dwarfs. Their surface dipole magnetic fields are comprised in the range 7.5 × 10 8 G B
In our previous treatment of neutron stars, we have developed the model fulfilling global and not... more In our previous treatment of neutron stars, we have developed the model fulfilling global and not local charge neutrality. In order to implement such a model, we have shown the essential role by the Thomas-Fermi equations, duly generalized to the case of electromagnetic field equations in a general relativistic framework, forming a coupled system of equations that we have denominated Einstein-Maxwell-Thomas-Fermi (EMTF) equations. From the microphysical point of view, the weak interactions are accounted for by requesting the \beta\ stability of the system, and the strong interactions by using the \sigma-\omega-\rho\ nuclear model, where \sigma, \omega\ and \rho\ are the mediator massive vector mesons. Here we examine the equilibrium configurations of slowly rotating neutron stars by using the Hartle formalism in the case of the EMTF equations indicated above. We integrate these equations of equilibrium for different central densities and circular angular velocities and compute the mass, polar and equatorial radii, angular momentum, eccentricity, moment of inertia, as well as quadrupole moment of the configurations. Both the Keplerian mass-shedding limit and the axisymmetric secular instability are used to construct the new mass-radius relation. We compute the maximum and minimum masses and rotation frequencies of neutron stars. We compare and contrast all the results for the global and local charge neutrality cases.
We have recently proved the impossibility of imposing the condition of local charge neutrality in... more We have recently proved the impossibility of imposing the condition of local charge neutrality in a self-gravitating system of degenerate neutrons, protons and electrons in beta\betabeta-equilibrium. The coupled system of the general relativistic Thomas-Fermi equations and the Einstein-Maxwell equations have been shown to supersede the traditional Tolman-Oppenheimer-Volkoff equations. Here we present the Newtonian limit of the new equilibrium equations. We also extend the treatment to the case of finite temperatures and finally we give the explicit demonstration of the constancy of the Klein potentials in the case of finite temperatures generalizing the condition of constancy of the general relativistic Fermi energies in the case of zero temperatures.
On the dyadotorus
Aps Meeting Abstracts, Apr 1, 2008
The ``dyadotorus'' is defined as the region around a Kerr-Newman black hole where pair creation b... more The ``dyadotorus'' is defined as the region around a Kerr-Newman black hole where pair creation by vacuum polarization occurs. This concept extends to the case of stationary geometries the concept of ``dyadosphere'' already introduced in the static case in the Reissner-Nordstrom geometry. The energetics of the dyadotorii, their topology and embedding diagrams are compared and contrasted to the ones of the black hole.
It has been shown recently that taking into account strong, weak, electromagnetic, and gravitatio... more It has been shown recently that taking into account strong, weak, electromagnetic, and gravitational interactions, and fulfilling the global charge neutrality of the system, a transition layer will happen between the core and crust of neutron stars, at the nuclear saturation density. We use relativistic mean field theory together with the Thomas-Fermi approximation to study the detailed structure of this transition layer and calculate its surface and Coulomb energy. We find that the surface tension is proportional to a power-law function of the baryon number density in the core bulk region. We also analyze the influence of the electron component and the gravitational field on the structure of the transition layer and the value of the surface tension to compare and contrast with known phenomenological results in nuclear physics. Based on the above results we study the instability against Bohr-Wheeler surface deformations in the case of neutron stars obeying global charge neutrality. Assuming the core-crust transition at nuclear density ρ core ≈ 2.7 × 10 14 g cm −3 , we find that the instability sets the upper limit to the crust density, ρ crit crust ≈ 1.2 × 10 14 g cm −3 . This result implies a nonzero lower limit to the maximum electric field of the core-crust transition surface and makes inaccessible a limit of quasilocal charge neutrality in the limit ρ crust = ρ core . The general framework presented here can be also applied to study the stability of sharp phase transitions in hybrid stars as well as in strange stars, both bare and with outer crust. The results of this work open the way to a more general analysis of the stability of these transition surfaces, accounting for other effects such as gravitational binding, centrifugal repulsion, magnetic field induced by rotating electric field, and therefore magnetic dipole-dipole interactions.
Relativistic Thomas-Fermi treatment of compressed atoms and compressed nuclear matter cores of stellar dimensions
Phys Rev C, 2011
The Feynman-Metropolis-Teller treatment of compressed atoms is extended to the relativistic regim... more The Feynman-Metropolis-Teller treatment of compressed atoms is extended to the relativistic regimes. Each atomic configuration is confined by a Wigner-Seitz cell and is characterized by a positive electron Fermi energy. The nonrelativistic treatment assumes a pointlike nucleus and infinite values of the electron Fermi energy can be attained. In the relativistic treatment there exists a limiting configuration, reached when the Wigner-Seitz cell radius equals the radius of the nucleus, with a maximum value of the electron Fermi energy (EeF)max, here expressed analytically in the ultrarelativistic approximation. The corrections given by the relativistic Thomas-Fermi-Dirac exchange term are also evaluated and shown to be generally small and negligible in the relativistic high-density regime. The dependence of the relativistic electron Fermi energies by compression for selected nuclei are compared and contrasted to the nonrelativistic ones and to the ones obtained in the uniform approximation. The relativistic Feynman-Metropolis-Teller approach here presented overcomes some difficulties in the Salpeter approximation generally adopted for compressed matter in physics and astrophysics. The treatment is then extrapolated to compressed nuclear matter cores of stellar dimensions with A≃(mPlanck/mn)3~1057 or Mcore~M⊙. A new family of equilibrium configurations exists for selected values of the electron Fermi energy varying in the range 0<EeF⩽(EeF)max. Such configurations fulfill global but not local charge neutrality. They have electric fields on the core surface, increasing for decreasing values of the electron Fermi energy reaching values much larger than the critical value Ec=me2c3/(eℏ) for EeF=0. We compare and contrast our results with the ones of Thomas-Fermi model in strange stars.
On the electrodynamics properties of nuclear matter cores
It is by now clear that Gamma ray Bursts originate from an electron positron plasma formed during... more It is by now clear that Gamma ray Bursts originate from an electron positron plasma formed during the process of gravitational collapse to a Black Hole. It is crucial to identify the initial conditions in the neutron star core originating such a collapse which give origin to the vast electrodynamics process originating such an electron positron plasma during the late phases of the collapse as the horizon of the Black Hole is reached. We present a new approach, based on a ultra-relativistic Thomas-Fermi approach, to the nuclear matter in bulk enforcing the condition of global charge neutrality as opposed to the local charge neutrality usually imposed. A new ground state is found that can differ by 1049 ergs from the ones where local charge neutrality is implemented. Electric fields close to the critical value can exist at the surface of the core at the onset of the gravitational instability. We outline consequences of these results in nuclear physics, in the formation process of neutron stars and the supernovae emission in the X and Gamma rays as well as possibly in the process of ejection of the remnant.
Moment of inertia, radii, surface emission from a new theoretical understanding of Neutron Stars
We formulate the equations of neutron stars taking into account the strong, weak, electromagnetic... more We formulate the equations of neutron stars taking into account the strong, weak, electromagnetic and gravitational interactions within a new fully general relativistic Thomas-Fermi approach. The nuclear interactions are described by the exchange of the sigma, omega, and rho virtual mesons. The constancy of the generalized chemical potential, for short Klein potentials, of the particle species is required as a condition of equilibrium throughout the star. The continuity of the Klein potentials in the transition from the core to the crust imposes the presence of a strong electric field larger than the critical one for vacuum polarization. Correspondingly, the electron density decreases in the core-crust transition region. Such a phenomenon leads to neutron stars with crusts with masses and thickness smaller with respect to the ones of traditional neutron star configurations that satisfy local charge neutrality from the center all the way up to the surface. We present new estimates of...
The Thirteenth Marcel Grossmann Meeting, 2014
We describe one of the so-called low magnetic field magnetars SGR 0418+5729, as a massive fast ro... more We describe one of the so-called low magnetic field magnetars SGR 0418+5729, as a massive fast rotating highly magnetized white dwarf following Malheiro et. al. We give bounds for the mass, radius, moment of inertia, and magnetic field for these sources, by requesting the stability of realistic general relativistic uniformly rotating configurations. Based on these parameters, we improve the theoretical prediction of the lower limit of the spin-down rate of SGR 0418+5729. In addition, we compute the electron cyclotron frequencies corresponding to the predicted surface magnetic fields.
A general relativistic Thomas-Fermi treatment of neutron star cores
ABSTRACT We formulate the set of self-consistent ground-state equilibrium equations of a system o... more ABSTRACT We formulate the set of self-consistent ground-state equilibrium equations of a system of degenerate neutrons, protons and electrons in beta equilibrium taking into account quantum statistics, electro-weak, and strong interactions, within the framework of general relativity. The strong interaction between nucleons is modeled through sigma-omega-rho meson exchange in the context of the extended Walecka model, all duly expressed in general relativity. We demonstrate that, as in the non-interacting case, the thermodynamic equilibrium condition given by the constancy of the Fermi energy of each particle-specie can be properly generalized to include the contribution of all fields.
Extracting multipole moments of neutron stars from quasi-periodic oscillations in low mass X-ray binaries
Astronomy Reports, 2015
A New Family of Neutron Star Models: Global Neutrality Versus Local Neutrality
The Twelfth Marcel Grossmann Meeting - On Recent Developments in Theoretical and Experimental General Relativity Astrophysics and Relativistic Field Theories - Proceedings of the MG12 Meeting on General Relativity, 2012
ABSTRACT We formulate the set of self-consistent ground-state equilibrium equations of a system o... more ABSTRACT We formulate the set of self-consistent ground-state equilibrium equations of a system of degenerate neutrons, protons and electrons in beta equilibrium taking into account quantum statistics and electro-weak interactions within the framework of general relativity. We point out the existence of globally neutral neutron star configurations in contrast with the traditional locally neutral ones. We discuss new gravito-electrodynamic effects present in such globally neutral neutron star equilibrium configurations.
From Compressed Atoms to Compressed Massive Nuclear Density Cores
The Twelfth Marcel Grossmann Meeting - On Recent Developments in Theoretical and Experimental General Relativity Astrophysics and Relativistic Field Theories - Proceedings of the MG12 Meeting on General Relativity, 2012
On Degenerate Compressed Atoms and Compressed Nuclear Matter Cores of Stellar Dimensions
International Journal of Modern Physics: Conference Series, 2012
ABSTRACT The relativistic generalization of the Feynman, Metropolis and Teller treatment of compr... more ABSTRACT The relativistic generalization of the Feynman, Metropolis and Teller treatment of compressed atoms is obtained. Each atomic configuration is confined by a Wigner-Seitz cell and is characterized by a positive electron Fermi energy. There exists a limiting configuration, reached when the Wigner-Seitz cell radius equals the radius of the nucleus, with a maximum value of the electron Fermi energy (EeF)max, here expressed analytically in the ultra-relativistic approximation. The treatment is then extrapolated to compressed nuclear matter cores of stellar dimensions with A ≃ (mPlanck/mn)3 1057 or Mcore M⊙. A new family of equilibrium configurations exists for selected values of the electron Fermi energy varying in the range 0 < EeF <= (EeF)max. Such configurations fulfill global but not local charge neutrality. They have electric fields on the core surface, increasing for decreasing values of the electron Fermi energy reaching values much larger than the critical value Ec = me2c^3/(e\hbar ), for EeF = 0.
EAS Publications Series, 2013
The possibility to divide GRBs in different subclasses allow to understand better the physics und... more The possibility to divide GRBs in different subclasses allow to understand better the physics underlying their emission mechanisms and progenitors. The induced gravitational collapse scenario proposes a binary progenitor to explain the time-sequence in GRBs-SNe. We show the existence of a common behavior of the late decay of the Xray afterglow emission of this subclass of GRBs, pointing to a common physical mechanism of their late emission, consistent with the IGC picture.
Gravitation and Cosmology, 2014
In light of the relativistic precession model, we present here detailed analyses, extending the o... more In light of the relativistic precession model, we present here detailed analyses, extending the ones performed in the Schwarzschild and Kerr spacetimes. We consider the kilohertz quasi-periodic oscillations in the Hartle-Thorne spacetime, which describes the gravitational field of a rotating and deformed object. We derive the analytic formulas for the epicyclic frequencies in the Hartel-Thorne spacetime and by means of these frequencies we interpret the kilohertz quasi-periodic oscillations of low-mass X-ray binaries of the atoll and Z -sources, on the basis of the relativistic precession model. Particularly we perform analyzes for Z -source: GX 5-1. We show that the quasi-periodic oscillations data can provide information on the parameters, namely, the mass, angular momentum and quadrupole moment of the compact objects in the low-mass X-ray binaries.
Massive, highly magnetized white dwarfs with fields up to 10 9 G have been observed and theoretic... more Massive, highly magnetized white dwarfs with fields up to 10 9 G have been observed and theoretically used for the description of a variety of astrophysical phenomena. Ultramagnetized white dwarfs with uniform interior fields up to 10 18 G have been recently purported to obey a new maximum mass limit, M max ≈ 2.58 M , which largely overcomes the traditional Chandrasekhar value, M Ch ≈ 1.44 M . Such a larger limit would make these astrophysical objects viable candidates for the explanation of the superluminous population of Type Ia supernovae. We show that several macro and micro physical aspects such as gravitational, dynamical stability, breaking of spherical symmetry, general relativity, inverse β decay, and pycnonuclear fusion reactions are of most relevance for the self-consistent description of the structure and assessment of stability of these objects. It is shown in this work that the first family of magnetized white dwarfs indeed satisfy all the criteria of stability, while the ultramagnetized white dwarfs are very unlikely to exist in nature since they violate minimal requests of stability. Therefore, the canonical Chandrasekhar mass limit of white dwarfs still has to be applied.
International Journal of Modern Physics E, 2011
The properties of uniformly rotating white dwarfs are analyzed within the framework of general re... more The properties of uniformly rotating white dwarfs are analyzed within the framework of general relativity. Hartle's formalism is applied to construct self-consistently the internal and external solutions to the Einstein equations. The mass, the radius, the moment of inertia and quadrupole moment of rotating white dwarfs have been calculated as a function of both the central density and rotation period of the star. The maximum mass of rotating white dwarfs for stable configurations has been obtained.