3.10 Facultad de Física

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Black holes in scale-dependent frameworks.
(2019) Rincón, Ángel; Koch, Benjamin; Pontificia Universidad Católica de Chile. Facultad de Física
In the present thesis, we investigate the scale–dependence of some well known black hole solutions in 2+1 dimensions at the level of the effective action in the presence of a cosmological constant or an electrical source. We promote the classical parameters of the theory, {G0,(· · ·)0}, to scale–dependent couplings, {Gk,(· · ·)k} and then we solve the corresponding effective Einstein field equations. To close the system of equations we impose the null energy condition. This last condition (valid in arbitrary dimension) provides a differential equation which, after solving it, allows to obtain in a simple way the specific form of the gravitational coupling. Furthermore, perfect-fluid like parameters are induced via the scale-dependent gravitational coupling. Finally, to exemplify the effect of the running of the couplings on the properties of the scale-dependent black hole solutions, we show a few concrete examples.In the present thesis, we investigate the scale–dependence of some well known black hole solutions in 2+1 dimensions at the level of the effective action in the presence of a cosmological constant or an electrical source. We promote the classical parameters of the theory, {G0,(· · ·)0}, to scale–dependent couplings, {Gk,(· · ·)k} and then we solve the corresponding effective Einstein field equations. To close the system of equations we impose the null energy condition. This last condition (valid in arbitrary dimension) provides a differential equation which, after solving it, allows to obtain in a simple way the specific form of the gravitational coupling. Furthermore, perfect-fluid like parameters are induced via the scale-dependent gravitational coupling. Finally, to exemplify the effect of the running of the couplings on the properties of the scale-dependent black hole solutions, we show a few concrete examples.In the present thesis, we investigate the scale–dependence of some well known black hole solutions in 2+1 dimensions at the level of the effective action in the presence of a cosmological constant or an electrical source. We promote the classical parameters of the theory, {G0,(· · ·)0}, to scale–dependent couplings, {Gk,(· · ·)k} and then we solve the corresponding effective Einstein field equations. To close the system of equations we impose the null energy condition. This last condition (valid in arbitrary dimension) provides a differential equation which, after solving it, allows to obtain in a simple way the specific form of the gravitational coupling. Furthermore, perfect-fluid like parameters are induced via the scale-dependent gravitational coupling. Finally, to exemplify the effect of the running of the couplings on the properties of the scale-dependent black hole solutions, we show a few concrete examples.In the present thesis, we investigate the scale–dependence of some well known black hole solutions in 2+1 dimensions at the level of the effective action in the presence of a cosmological constant or an electrical source. We promote the classical parameters of the theory, {G0,(· · ·)0}, to scale–dependent couplings, {Gk,(· · ·)k} and then we solve the corresponding effective Einstein field equations. To close the system of equations we impose the null energy condition. This last condition (valid in arbitrary dimension) provides a differential equation which, after solving it, allows to obtain in a simple way the specific form of the gravitational coupling. Furthermore, perfect-fluid like parameters are induced via the scale-dependent gravitational coupling. Finally, to exemplify the effect of the running of the couplings on the properties of the scale-dependent black hole solutions, we show a few concrete examples.
Contrasting neutron star heating mechanisms with Hubble Space Telescope observations
(2018) Rodríguez Tapia, Luis; Reisenegger, Andreas; Pontificia Universidad Católica de Chile. Instituto de Física
Si las estrellas de neutrones se enfriaran pasivamente, se esperaría que se vuelvan indetectables en un tiempo menor a 107 años, al alcanzar bajas temperaturas T < 104 K. Sin embargo, radiación del tipo ultravioleta, que implica temperaturas superficiales T ∼ 105 K, fue detectada desde los pulsares de Giga años PSR J0437- 4715 y PSR J2124-3358 y también desde el pulsar B0950+08 cuya edad es ∼ 107 años. Esta discrepancia puede ser explicada por un grupo de mecanismos de calentamiento propuestos en la literatura. Usando el código de Petrovich y Reisenegger se calcularon curvas de evolución térmica considerando diferentes mecanismos de calentamiento. Estas fueron contrastadas con las temperaturas inferidas a partir de las observaciones de los pulsares para determinar cuál es la principal fuente de emisión térmica de las estrellas de neutrones. Encontramos que el calentamiento rotoquímico, reacciones nucleares en las capas profundas de la corteza y el calor liberado por la fricción de vórtices superfluidos pueden mantener la estrella lo suficientemente caliente más allá del tiempo estándar de enfriamiento pasivo y explicar las observaciones.Si las estrellas de neutrones se enfriaran pasivamente, se esperaría que se vuelvan indetectables en un tiempo menor a 107 años, al alcanzar bajas temperaturas T < 104 K. Sin embargo, radiación del tipo ultravioleta, que implica temperaturas superficiales T ∼ 105 K, fue detectada desde los pulsares de Giga años PSR J0437- 4715 y PSR J2124-3358 y también desde el pulsar B0950+08 cuya edad es ∼ 107 años. Esta discrepancia puede ser explicada por un grupo de mecanismos de calentamiento propuestos en la literatura. Usando el código de Petrovich y Reisenegger se calcularon curvas de evolución térmica considerando diferentes mecanismos de calentamiento. Estas fueron contrastadas con las temperaturas inferidas a partir de las observaciones de los pulsares para determinar cuál es la principal fuente de emisión térmica de las estrellas de neutrones. Encontramos que el calentamiento rotoquímico, reacciones nucleares en las capas profundas de la corteza y el calor liberado por la fricción de vórtices superfluidos pueden mantener la estrella lo suficientemente caliente más allá del tiempo estándar de enfriamiento pasivo y explicar las observaciones.
Magneto-thermal evolution of neutron star cores in the “strong-coupling regime”
(2020) Moraga Vent, Nicolás Andrés; Reisenegger, Andreas; Pontificia Universidad Católica de Chile. Instituto de Física
In this thesis we study a young neutron star, with internal temperatures T >10^9 K, where the particles in the core are strongly coupled by collisional forces and can convert into each other by beta decays, in the so called ``strong-coupling regime``. At this stage, the magnetic field induces small fluid displacements, changing the local chemical composition and generating pressure gradient forces, which tend to be erased by beta decays. Depending on the strength of the chemical departure, this reactions can lead to a non-trivial thermal evolution as a consequence of the magnetic feedback. This mechanism converts magneticto thermal energy and could explain the high surface luminosity of magnetars (highly magnetize neutron stars). In this thesis, we present the first long-term magneto-thermal simulation of a neutron star core in this regime. We concluded that, for internal magnetic field strength field B > 10^16 G, the possibility of a magnetic feedback due to the chemical departure is not possible because it would occur when the ambipolar heating (friction between charged particles and neutrons) is more likely to heat the core.
Thermodynamics of graviton condensate and the Kiselev black hole
(2020) Mancilla Pérez, Robinson Humberto; Alfaro Solís, Jorge Luis; Pontificia Universidad Católica de Chile. Instituto de Física
In this thesis, we will present the thermodynamic study of a model that considers the black hole as a condensation of gravitons (55) (56). We will obtain a correction to the Hawking temperature and a negative pressure for a black hole of mass M. In this way, the graviton condensate, which is assumed to be at the critical point defined by the condition µch=0, will have well-defined thermodynamic quantities P, V , Th, S, and U as any other Bose-Einstein condensate. We will also discuss the Kiselev black hole, which has the capacity to parametrize the most well-known spherically symmetric black holes. We will show that this is true, even at the thermodynamic level. Finally, we will present a new metric, which we will call the BEC-Kiselev black hole, that will allow us to extend the graviton condensate to the case of solutions with different types of the energy-momentum tensor.In this thesis, we will present the thermodynamic study of a model that considers the black hole as a condensation of gravitons (55) (56). We will obtain a correction to the Hawking temperature and a negative pressure for a black hole of mass M. In this way, the graviton condensate, which is assumed to be at the critical point defined by the condition µch=0, will have well-defined thermodynamic quantities P, V , Th, S, and U as any other Bose-Einstein condensate. We will also discuss the Kiselev black hole, which has the capacity to parametrize the most well-known spherically symmetric black holes. We will show that this is true, even at the thermodynamic level. Finally, we will present a new metric, which we will call the BEC-Kiselev black hole, that will allow us to extend the graviton condensate to the case of solutions with different types of the energy-momentum tensor.In this thesis, we will present the thermodynamic study of a model that considers the black hole as a condensation of gravitons (55) (56). We will obtain a correction to the Hawking temperature and a negative pressure for a black hole of mass M. In this way, the graviton condensate, which is assumed to be at the critical point defined by the condition µch=0, will have well-defined thermodynamic quantities P, V , Th, S, and U as any other Bose-Einstein condensate. We will also discuss the Kiselev black hole, which has the capacity to parametrize the most well-known spherically symmetric black holes. We will show that this is true, even at the thermodynamic level. Finally, we will present a new metric, which we will call the BEC-Kiselev black hole, that will allow us to extend the graviton condensate to the case of solutions with different types of the energy-momentum tensor.In this thesis, we will present the thermodynamic study of a model that considers the black hole as a condensation of gravitons (55) (56). We will obtain a correction to the Hawking temperature and a negative pressure for a black hole of mass M. In this way, the graviton condensate, which is assumed to be at the critical point defined by the condition µch=0, will have well-defined thermodynamic quantities P, V , Th, S, and U as any other Bose-Einstein condensate. We will also discuss the Kiselev black hole, which has the capacity to parametrize the most well-known spherically symmetric black holes. We will show that this is true, even at the thermodynamic level. Finally, we will present a new metric, which we will call the BEC-Kiselev black hole, that will allow us to extend the graviton condensate to the case of solutions with different types of the energy-momentum tensor.In this thesis, we will present the thermodynamic study of a model that considers the black hole as a condensation of gravitons (55) (56). We will obtain a correction to the Hawking temperature and a negative pressure for a black hole of mass M. In this way, the graviton condensate, which is assumed to be at the critical point defined by the condition µch=0, will have well-defined thermodynamic quantities P, V , Th, S, and U as any other Bose-Einstein condensate. We will also discuss the Kiselev black hole, which has the capacity to parametrize the most well-known spherically symmetric black holes. We will show that this is true, even at the thermodynamic level. Finally, we will present a new metric, which we will call the BEC-Kiselev black hole, that will allow us to extend the graviton condensate to the case of solutions with different types of the energy-momentum tensor.In this thesis, we will present the thermodynamic study of a model that considers the black hole as a condensation of gravitons (55) (56). We will obtain a correction to the Hawking temperature and a negative pressure for a black hole of mass M. In this way, the graviton condensate, which is assumed to be at the critical point defined by the condition µch=0, will have well-defined thermodynamic quantities P, V , Th, S, and U as any other Bose-Einstein condensate. We will also discuss the Kiselev black hole, which has the capacity to parametrize the most well-known spherically symmetric black holes. We will show that this is true, even at the thermodynamic level. Finally, we will present a new metric, which we will call the BEC-Kiselev black hole, that will allow us to extend the graviton condensate to the case of solutions with different types of the energy-momentum tensor.In this thesis, we will present the thermodynamic study of a model that considers the black hole as a condensation of gravitons (55) (56). We will obtain a correction to the Hawking temperature and a negative pressure for a black hole of mass M. In this way, the graviton condensate, which is assumed to be at the critical point defined by the condition µch=0, will have well-defined thermodynamic quantities P, V , Th, S, and U as any other Bose-Einstein condensate. We will also discuss the Kiselev black hole, which has the capacity to parametrize the most well-known spherically symmetric black holes. We will show that this is true, even at the thermodynamic level. Finally, we will present a new metric, which we will call the BEC-Kiselev black hole, that will allow us to extend the graviton condensate to the case of solutions with different types of the energy-momentum tensor.In this thesis, we will present the thermodynamic study of a model that considers the black hole as a condensation of gravitons (55) (56). We will obtain a correction to the Hawking temperature and a negative pressure for a black hole of mass M. In this way, the graviton condensate, which is assumed to be at the critical point defined by the condition µch=0, will have well-defined thermodynamic quantities P, V , Th, S, and U as any other Bose-Einstein condensate. We will also discuss the Kiselev black hole, which has the capacity to parametrize the most well-known spherically symmetric black holes. We will show that this is true, even at the thermodynamic level. Finally, we will present a new metric, which we will call the BEC-Kiselev black hole, that will allow us to extend the graviton condensate to the case of solutions with different types of the energy-momentum tensor.In this thesis, we will present the thermodynamic study of a model that considers the black hole as a condensation of gravitons (55) (56). We will obtain a correction to the Hawking temperature and a negative pressure for a black hole of mass M. In this way, the graviton condensate, which is assumed to be at the critical point defined by the condition µch=0, will have well-defined thermodynamic quantities P, V , Th, S, and U as any other Bose-Einstein condensate. We will also discuss the Kiselev black hole, which has the capacity to parametrize the most well-known spherically symmetric black holes. We will show that this is true, even at the thermodynamic level. Finally, we will present a new metric, which we will call the BEC-Kiselev black hole, that will allow us to extend the graviton condensate to the case of solutions with different types of the energy-momentum tensor.In this thesis, we will present the thermodynamic study of a model that considers the black hole as a condensation of gravitons (55) (56). We will obtain a correction to the Hawking temperature and a negative pressure for a black hole of mass M. In this way, the graviton condensate, which is assumed to be at the critical point defined by the condition µch=0, will have well-defined thermodynamic quantities P, V , Th, S, and U as any other Bose-Einstein condensate. We will also discuss the Kiselev black hole, which has the capacity to parametrize the most well-known spherically symmetric black holes. We will show that this is true, even at the thermodynamic level. Finally, we will present a new metric, which we will call the BEC-Kiselev black hole, that will allow us to extend the graviton condensate to the case of solutions with different types of the energy-momentum tensor.

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