3.10 Facultad de Física

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Cosmic inflation in modified models of gravity and an analysis on gravitational waves
(2021) Gamonal San Martín, Mauricio; Alfaro Solís, Jorge Luis; Pontificia Universidad Católica de Chile. Facultad de Física
This work comprises three different lines of research related to the study of cosmological inflation and the propagation of gravitational waves. In the first issue, we developed -for the first time in a systematic way- the slow-roll approximation for a single field inflaton within the framework of f(R,T) gravity, a modified model of gravity such that the Lagrangian is a function of the scalar curvature and the trace of the energy-momentum tensor. We obtained the modified slow-roll parameters and the spectral indices by choosing a minimal coupling between matter and gravity. We computed these quantities for several models and contrasted the predictions with the constraints of the Planck data, obtaining corrections to the Starobinsky model. In the second line of research, we studied how a free Lorentz-valued bosonic 0-form coupled to Einstein-Cartan gravity's action can be considered the inflaton field. In this model, the interacting terms of the fields come directly from the torsionful contributions of the action. Hence, the inflationary dynamics can be extended so that we can define an effective potential that describes the evolution of the background fields. We found that for a particular combination of initial conditions, the model could adequately guarantee the slow-roll conditions over more than 55 e-folds. However, a more detailed analysis is required to confirm the viability of this inflationary scenario. Finally, we addressed a different problem related to the propagation of low-frequency gravitational waves coming from sources located at cosmological distances. Within the linearized regime of gravity, we performed a coordinate system transformation between a frame which origin is the source of gravitational waves and the comoving frame of the FLRW metric. Then, we studied the observational consequences in Pulsar Timing Arrays experiments, finding a non-trivial modification to the timing residual of pulsars that depends on the value of the Hubble constant.
Exploring the landscape of very special relativity
(2020) Soto Villarroel, Alex; Alfaro Solís, Jorge Luis; Pontificia Universidad Católica de Chile. Instituto de Física
In this thesis we study the Very Special Relativity (VSR) framework. In particular we put the emphasis in the QED sector. We present the basics of the Lorentz group and the subgroup SIM(2), which is the symmetry of nature in this framework instead of the full Lorentz group. This symmetry allows introducing terms like n.p/n.q, where n transforms with a phase under SIM(2) transformations. With this construction, we can explain the neutrino mass without the addition of new particles. We explore VSR in two dimensions, showing that the Lorentz group allows VSR terms. This fact shows that we can revisit QED2. We compute the photon self-energy and the axial anomaly, finding differences from the standard result. In addition, in four dimensions, we review the electron self-energy, and we discuss the importance of a prescription to regulate infrared divergencies in the VSR integrals. We present a prescription to use when we introduce a possible gauge-invariant photon mass in the electron self-energy computation. The Coulomb scattering is presented as an example of a simple process that can be computed, showing a small signal of the vector n.In this thesis we study the Very Special Relativity (VSR) framework. In particular we put the emphasis in the QED sector. We present the basics of the Lorentz group and the subgroup SIM(2), which is the symmetry of nature in this framework instead of the full Lorentz group. This symmetry allows introducing terms like n.p/n.q, where n transforms with a phase under SIM(2) transformations. With this construction, we can explain the neutrino mass without the addition of new particles. We explore VSR in two dimensions, showing that the Lorentz group allows VSR terms. This fact shows that we can revisit QED2. We compute the photon self-energy and the axial anomaly, finding differences from the standard result. In addition, in four dimensions, we review the electron self-energy, and we discuss the importance of a prescription to regulate infrared divergencies in the VSR integrals. We present a prescription to use when we introduce a possible gauge-invariant photon mass in the electron self-energy computation. The Coulomb scattering is presented as an example of a simple process that can be computed, showing a small signal of the vector n.In this thesis we study the Very Special Relativity (VSR) framework. In particular we put the emphasis in the QED sector. We present the basics of the Lorentz group and the subgroup SIM(2), which is the symmetry of nature in this framework instead of the full Lorentz group. This symmetry allows introducing terms like n.p/n.q, where n transforms with a phase under SIM(2) transformations. With this construction, we can explain the neutrino mass without the addition of new particles. We explore VSR in two dimensions, showing that the Lorentz group allows VSR terms. This fact shows that we can revisit QED2. We compute the photon self-energy and the axial anomaly, finding differences from the standard result. In addition, in four dimensions, we review the electron self-energy, and we discuss the importance of a prescription to regulate infrared divergencies in the VSR integrals. We present a prescription to use when we introduce a possible gauge-invariant photon mass in the electron self-energy computation. The Coulomb scattering is presented as an example of a simple process that can be computed, showing a small signal of the vector n.In this thesis we study the Very Special Relativity (VSR) framework. In particular we put the emphasis in the QED sector. We present the basics of the Lorentz group and the subgroup SIM(2), which is the symmetry of nature in this framework instead of the full Lorentz group. This symmetry allows introducing terms like n.p/n.q, where n transforms with a phase under SIM(2) transformations. With this construction, we can explain the neutrino mass without the addition of new particles. We explore VSR in two dimensions, showing that the Lorentz group allows VSR terms. This fact shows that we can revisit QED2. We compute the photon self-energy and the axial anomaly, finding differences from the standard result. In addition, in four dimensions, we review the electron self-energy, and we discuss the importance of a prescription to regulate infrared divergencies in the VSR integrals. We present a prescription to use when we introduce a possible gauge-invariant photon mass in the electron self-energy computation. The Coulomb scattering is presented as an example of a simple process that can be computed, showing a small signal of the vector n.In this thesis we study the Very Special Relativity (VSR) framework. In particular we put the emphasis in the QED sector. We present the basics of the Lorentz group and the subgroup SIM(2), which is the symmetry of nature in this framework instead of the full Lorentz group. This symmetry allows introducing terms like n.p/n.q, where n transforms with a phase under SIM(2) transformations. With this construction, we can explain the neutrino mass without the addition of new particles. We explore VSR in two dimensions, showing that the Lorentz group allows VSR terms. This fact shows that we can revisit QED2. We compute the photon self-energy and the axial anomaly, finding differences from the standard result. In addition, in four dimensions, we review the electron self-energy, and we discuss the importance of a prescription to regulate infrared divergencies in the VSR integrals. We present a prescription to use when we introduce a possible gauge-invariant photon mass in the electron self-energy computation. The Coulomb scattering is presented as an example of a simple process that can be computed, showing a small signal of the vector n.In this thesis we study the Very Special Relativity (VSR) framework. In particular we put the emphasis in the QED sector. We present the basics of the Lorentz group and the subgroup SIM(2), which is the symmetry of nature in this framework instead of the full Lorentz group. This symmetry allows introducing terms like n.p/n.q, where n transforms with a phase under SIM(2) transformations. With this construction, we can explain the neutrino mass without the addition of new particles. We explore VSR in two dimensions, showing that the Lorentz group allows VSR terms. This fact shows that we can revisit QED2. We compute the photon self-energy and the axial anomaly, finding differences from the standard result. In addition, in four dimensions, we review the electron self-energy, and we discuss the importance of a prescription to regulate infrared divergencies in the VSR integrals. We present a prescription to use when we introduce a possible gauge-invariant photon mass in the electron self-energy computation. The Coulomb scattering is presented as an example of a simple process that can be computed, showing a small signal of the vector n.In this thesis we study the Very Special Relativity (VSR) framework. In particular we put the emphasis in the QED sector. We present the basics of the Lorentz group and the subgroup SIM(2), which is the symmetry of nature in this framework instead of the full Lorentz group. This symmetry allows introducing terms like n.p/n.q, where n transforms with a phase under SIM(2) transformations. With this construction, we can explain the neutrino mass without the addition of new particles. We explore VSR in two dimensions, showing that the Lorentz group allows VSR terms. This fact shows that we can revisit QED2. We compute the photon self-energy and the axial anomaly, finding differences from the standard result. In addition, in four dimensions, we review the electron self-energy, and we discuss the importance of a prescription to regulate infrared divergencies in the VSR integrals. We present a prescription to use when we introduce a possible gauge-invariant photon mass in the electron self-energy computation. The Coulomb scattering is presented as an example of a simple process that can be computed, showing a small signal of the vector n.In this thesis we study the Very Special Relativity (VSR) framework. In particular we put the emphasis in the QED sector. We present the basics of the Lorentz group and the subgroup SIM(2), which is the symmetry of nature in this framework instead of the full Lorentz group. This symmetry allows introducing terms like n.p/n.q, where n transforms with a phase under SIM(2) transformations. With this construction, we can explain the neutrino mass without the addition of new particles. We explore VSR in two dimensions, showing that the Lorentz group allows VSR terms. This fact shows that we can revisit QED2. We compute the photon self-energy and the axial anomaly, finding differences from the standard result. In addition, in four dimensions, we review the electron self-energy, and we discuss the importance of a prescription to regulate infrared divergencies in the VSR integrals. We present a prescription to use when we introduce a possible gauge-invariant photon mass in the electron self-energy computation. The Coulomb scattering is presented as an example of a simple process that can be computed, showing a small signal of the vector n.In this thesis we study the Very Special Relativity (VSR) framework. In particular we put the emphasis in the QED sector. We present the basics of the Lorentz group and the subgroup SIM(2), which is the symmetry of nature in this framework instead of the full Lorentz group. This symmetry allows introducing terms like n.p/n.q, where n transforms with a phase under SIM(2) transformations. With this construction, we can explain the neutrino mass without the addition of new particles. We explore VSR in two dimensions, showing that the Lorentz group allows VSR terms. This fact shows that we can revisit QED2. We compute the photon self-energy and the axial anomaly, finding differences from the standard result. In addition, in four dimensions, we review the electron self-energy, and we discuss the importance of a prescription to regulate infrared divergencies in the VSR integrals. We present a prescription to use when we introduce a possible gauge-invariant photon mass in the electron self-energy computation. The Coulomb scattering is presented as an example of a simple process that can be computed, showing a small signal of the vector n.In this thesis we study the Very Special Relativity (VSR) framework. In particular we put the emphasis in the QED sector. We present the basics of the Lorentz group and the subgroup SIM(2), which is the symmetry of nature in this framework instead of the full Lorentz group. This symmetry allows introducing terms like n.p/n.q, where n transforms with a phase under SIM(2) transformations. With this construction, we can explain the neutrino mass without the addition of new particles. We explore VSR in two dimensions, showing that the Lorentz group allows VSR terms. This fact shows that we can revisit QED2. We compute the photon self-energy and the axial anomaly, finding differences from the standard result. In addition, in four dimensions, we review the electron self-energy, and we discuss the importance of a prescription to regulate infrared divergencies in the VSR integrals. We present a prescription to use when we introduce a possible gauge-invariant photon mass in the electron self-energy computation. The Coulomb scattering is presented as an example of a simple process that can be computed, showing a small signal of the vector n.
On the effects of the modification of the metric in the gravitational context
(2020) Rubio, Carlos; Alfaro Solís, Jorge Luis; Pontificia Universidad Católica de Chile. Instituto de Física
This thesis consists of two parts: In the first one, simple generic extensions of isotropic Durgapal–Fuloria stars to the anisotropic domain were presented. These anisotropic solutions were obtained by guided minimal deformations over the isotropic system. When the anisotropic sector interacts in a purely gravitational manner, the conditions to decouple both sectors, by means of the minimal geometric deformation approach, were satisfied. Hence, the anisotropic field equations were isolated resulting in a more treatable set of equations. The simplicity of the equations allows one to manipulate the anisotropies that can be implemented in a systematic way to obtain different realistic models for anisotropic configurations. Later on, the observational effects of such anisotropies when measuring the surface redshift were discussed. To conclude, the consistency of the application of the method over the obtained anisotropic configurations was shown. In this manner, different anisotropic sectors can be isolated from each other and modeled in a simple and systematic way. About 70% of the Universe is Dark Energy, but there is still no consensus in the physics community on what the nature of it is. Delta Gravity (DG) is an alternative theory of gravitation that could solve this cosmological problem. DG is able to explain the SNe data successfully. In this work, we explored the cosmological fluctuations that give rise to the CMB through a hydrodynamic approximation. We calculated the gauge transformations for the metric and the perfect fluid to present the equations of the evolution of cosmological fluctuations, providing the necessary equations to solve, in a semi-analytical way, the scalar TT Power Spectrum. These equations were useful for comparing the DG theory with astronomical observations and thus, being able to restrict the DG cosmology, testing the compatibility with the CMB Planck data, which are currently in contradiction with SNe data.This thesis consists of two parts: In the first one, simple generic extensions of isotropic Durgapal–Fuloria stars to the anisotropic domain were presented. These anisotropic solutions were obtained by guided minimal deformations over the isotropic system. When the anisotropic sector interacts in a purely gravitational manner, the conditions to decouple both sectors, by means of the minimal geometric deformation approach, were satisfied. Hence, the anisotropic field equations were isolated resulting in a more treatable set of equations. The simplicity of the equations allows one to manipulate the anisotropies that can be implemented in a systematic way to obtain different realistic models for anisotropic configurations. Later on, the observational effects of such anisotropies when measuring the surface redshift were discussed. To conclude, the consistency of the application of the method over the obtained anisotropic configurations was shown. In this manner, different anisotropic sectors can be isolated from each other and modeled in a simple and systematic way. About 70% of the Universe is Dark Energy, but there is still no consensus in the physics community on what the nature of it is. Delta Gravity (DG) is an alternative theory of gravitation that could solve this cosmological problem. DG is able to explain the SNe data successfully. In this work, we explored the cosmological fluctuations that give rise to the CMB through a hydrodynamic approximation. We calculated the gauge transformations for the metric and the perfect fluid to present the equations of the evolution of cosmological fluctuations, providing the necessary equations to solve, in a semi-analytical way, the scalar TT Power Spectrum. These equations were useful for comparing the DG theory with astronomical observations and thus, being able to restrict the DG cosmology, testing the compatibility with the CMB Planck data, which are currently in contradiction with SNe data.This thesis consists of two parts: In the first one, simple generic extensions of isotropic Durgapal–Fuloria stars to the anisotropic domain were presented. These anisotropic solutions were obtained by guided minimal deformations over the isotropic system. When the anisotropic sector interacts in a purely gravitational manner, the conditions to decouple both sectors, by means of the minimal geometric deformation approach, were satisfied. Hence, the anisotropic field equations were isolated resulting in a more treatable set of equations. The simplicity of the equations allows one to manipulate the anisotropies that can be implemented in a systematic way to obtain different realistic models for anisotropic configurations. Later on, the observational effects of such anisotropies when measuring the surface redshift were discussed. To conclude, the consistency of the application of the method over the obtained anisotropic configurations was shown. In this manner, different anisotropic sectors can be isolated from each other and modeled in a simple and systematic way. About 70% of the Universe is Dark Energy, but there is still no consensus in the physics community on what the nature of it is. Delta Gravity (DG) is an alternative theory of gravitation that could solve this cosmological problem. DG is able to explain the SNe data successfully. In this work, we explored the cosmological fluctuations that give rise to the CMB through a hydrodynamic approximation. We calculated the gauge transformations for the metric and the perfect fluid to present the equations of the evolution of cosmological fluctuations, providing the necessary equations to solve, in a semi-analytical way, the scalar TT Power Spectrum. These equations were useful for comparing the DG theory with astronomical observations and thus, being able to restrict the DG cosmology, testing the compatibility with the CMB Planck data, which are currently in contradiction with SNe data.This thesis consists of two parts: In the first one, simple generic extensions of isotropic Durgapal–Fuloria stars to the anisotropic domain were presented. These anisotropic solutions were obtained by guided minimal deformations over the isotropic system. When the anisotropic sector interacts in a purely gravitational manner, the conditions to decouple both sectors, by means of the minimal geometric deformation approach, were satisfied. Hence, the anisotropic field equations were isolated resulting in a more treatable set of equations. The simplicity of the equations allows one to manipulate the anisotropies that can be implemented in a systematic way to obtain different realistic models for anisotropic configurations. Later on, the observational effects of such anisotropies when measuring the surface redshift were discussed. To conclude, the consistency of the application of the method over the obtained anisotropic configurations was shown. In this manner, different anisotropic sectors can be isolated from each other and modeled in a simple and systematic way. About 70% of the Universe is Dark Energy, but there is still no consensus in the physics community on what the nature of it is. Delta Gravity (DG) is an alternative theory of gravitation that could solve this cosmological problem. DG is able to explain the SNe data successfully. In this work, we explored the cosmological fluctuations that give rise to the CMB through a hydrodynamic approximation. We calculated the gauge transformations for the metric and the perfect fluid to present the equations of the evolution of cosmological fluctuations, providing the necessary equations to solve, in a semi-analytical way, the scalar TT Power Spectrum. These equations were useful for comparing the DG theory with astronomical observations and thus, being able to restrict the DG cosmology, testing the compatibility with the CMB Planck data, which are currently in contradiction with SNe data.This thesis consists of two parts: In the first one, simple generic extensions of isotropic Durgapal–Fuloria stars to the anisotropic domain were presented. These anisotropic solutions were obtained by guided minimal deformations over the isotropic system. When the anisotropic sector interacts in a purely gravitational manner, the conditions to decouple both sectors, by means of the minimal geometric deformation approach, were satisfied. Hence, the anisotropic field equations were isolated resulting in a more treatable set of equations. The simplicity of the equations allows one to manipulate the anisotropies that can be implemented in a systematic way to obtain different realistic models for anisotropic configurations. Later on, the observational effects of such anisotropies when measuring the surface redshift were discussed. To conclude, the consistency of the application of the method over the obtained anisotropic configurations was shown. In this manner, different anisotropic sectors can be isolated from each other and modeled in a simple and systematic way. About 70% of the Universe is Dark Energy, but there is still no consensus in the physics community on what the nature of it is. Delta Gravity (DG) is an alternative theory of gravitation that could solve this cosmological problem. DG is able to explain the SNe data successfully. In this work, we explored the cosmological fluctuations that give rise to the CMB through a hydrodynamic approximation. We calculated the gauge transformations for the metric and the perfect fluid to present the equations of the evolution of cosmological fluctuations, providing the necessary equations to solve, in a semi-analytical way, the scalar TT Power Spectrum. These equations were useful for comparing the DG theory with astronomical observations and thus, being able to restrict the DG cosmology, testing the compatibility with the CMB Planck data, which are currently in contradiction with SNe data.This thesis consists of two parts: In the first one, simple generic extensions of isotropic Durgapal–Fuloria stars to the anisotropic domain were presented. These anisotropic solutions were obtained by guided minimal deformations over the isotropic system. When the anisotropic sector interacts in a purely gravitational manner, the conditions to decouple both sectors, by means of the minimal geometric deformation approach, were satisfied. Hence, the anisotropic field equations were isolated resulting in a more treatable set of equations. The simplicity of the equations allows one to manipulate the anisotropies that can be implemented in a systematic way to obtain different realistic models for anisotropic configurations. Later on, the observational effects of such anisotropies when measuring the surface redshift were discussed. To conclude, the consistency of the application of the method over the obtained anisotropic configurations was shown. In this manner, different anisotropic sectors can be isolated from each other and modeled in a simple and systematic way. About 70% of the Universe is Dark Energy, but there is still no consensus in the physics community on what the nature of it is. Delta Gravity (DG) is an alternative theory of gravitation that could solve this cosmological problem. DG is able to explain the SNe data successfully. In this work, we explored the cosmological fluctuations that give rise to the CMB through a hydrodynamic approximation. We calculated the gauge transformations for the metric and the perfect fluid to present the equations of the evolution of cosmological fluctuations, providing the necessary equations to solve, in a semi-analytical way, the scalar TT Power Spectrum. These equations were useful for comparing the DG theory with astronomical observations and thus, being able to restrict the DG cosmology, testing the compatibility with the CMB Planck data, which are currently in contradiction with SNe data.This thesis consists of two parts: In the first one, simple generic extensions of isotropic Durgapal–Fuloria stars to the anisotropic domain were presented. These anisotropic solutions were obtained by guided minimal deformations over the isotropic system. When the anisotropic sector interacts in a purely gravitational manner, the conditions to decouple both sectors, by means of the minimal geometric deformation approach, were satisfied. Hence, the anisotropic field equations were isolated resulting in a more treatable set of equations. The simplicity of the equations allows one to manipulate the anisotropies that can be implemented in a systematic way to obtain different realistic models for anisotropic configurations. Later on, the observational effects of such anisotropies when measuring the surface redshift were discussed. To conclude, the consistency of the application of the method over the obtained anisotropic configurations was shown. In this manner, different anisotropic sectors can be isolated from each other and modeled in a simple and systematic way. About 70% of the Universe is Dark Energy, but there is still no consensus in the physics community on what the nature of it is. Delta Gravity (DG) is an alternative theory of gravitation that could solve this cosmological problem. DG is able to explain the SNe data successfully. In this work, we explored the cosmological fluctuations that give rise to the CMB through a hydrodynamic approximation. We calculated the gauge transformations for the metric and the perfect fluid to present the equations of the evolution of cosmological fluctuations, providing the necessary equations to solve, in a semi-analytical way, the scalar TT Power Spectrum. These equations were useful for comparing the DG theory with astronomical observations and thus, being able to restrict the DG cosmology, testing the compatibility with the CMB Planck data, which are currently in contradiction with SNe data.This thesis consists of two parts: In the first one, simple generic extensions of isotropic Durgapal–Fuloria stars to the anisotropic domain were presented. These anisotropic solutions were obtained by guided minimal deformations over the isotropic system. When the anisotropic sector interacts in a purely gravitational manner, the conditions to decouple both sectors, by means of the minimal geometric deformation approach, were satisfied. Hence, the anisotropic field equations were isolated resulting in a more treatable set of equations. The simplicity of the equations allows one to manipulate the anisotropies that can be implemented in a systematic way to obtain different realistic models for anisotropic configurations. Later on, the observational effects of such anisotropies when measuring the surface redshift were discussed. To conclude, the consistency of the application of the method over the obtained anisotropic configurations was shown. In this manner, different anisotropic sectors can be isolated from each other and modeled in a simple and systematic way. About 70% of the Universe is Dark Energy, but there is still no consensus in the physics community on what the nature of it is. Delta Gravity (DG) is an alternative theory of gravitation that could solve this cosmological problem. DG is able to explain the SNe data successfully. In this work, we explored the cosmological fluctuations that give rise to the CMB through a hydrodynamic approximation. We calculated the gauge transformations for the metric and the perfect fluid to present the equations of the evolution of cosmological fluctuations, providing the necessary equations to solve, in a semi-analytical way, the scalar TT Power Spectrum. These equations were useful for comparing the DG theory with astronomical observations and thus, being able to restrict the DG cosmology, testing the compatibility with the CMB Planck data, which are currently in contradiction with SNe data.This thesis consists of two parts: In the first one, simple generic extensions of isotropic Durgapal–Fuloria stars to the anisotropic domain were presented. These anisotropic solutions were obtained by guided minimal deformations over the isotropic system. When the anisotropic sector interacts in a purely gravitational manner, the conditions to decouple both sectors, by means of the minimal geometric deformation approach, were satisfied. Hence, the anisotropic field equations were isolated resulting in a more treatable set of equations. The simplicity of the equations allows one to manipulate the anisotropies that can be implemented in a systematic way to obtain different realistic models for anisotropic configurations. Later on, the observational effects of such anisotropies when measuring the surface redshift were discussed. To conclude, the consistency of the application of the method over the obtained anisotropic configurations was shown. In this manner, different anisotropic sectors can be isolated from each other and modeled in a simple and systematic way. About 70% of the Universe is Dark Energy, but there is still no consensus in the physics community on what the nature of it is. Delta Gravity (DG) is an alternative theory of gravitation that could solve this cosmological problem. DG is able to explain the SNe data successfully. In this work, we explored the cosmological fluctuations that give rise to the CMB through a hydrodynamic approximation. We calculated the gauge transformations for the metric and the perfect fluid to present the equations of the evolution of cosmological fluctuations, providing the necessary equations to solve, in a semi-analytical way, the scalar TT Power Spectrum. These equations were useful for comparing the DG theory with astronomical observations and thus, being able to restrict the DG cosmology, testing the compatibility with the CMB Planck data, which are currently in contradiction with SNe data.This thesis consists of two parts: In the first one, simple generic extensions of isotropic Durgapal–Fuloria stars to the anisotropic domain were presented. These anisotropic solutions were obtained by guided minimal deformations over the isotropic system. When the anisotropic sector interacts in a purely gravitational manner, the conditions to decouple both sectors, by means of the minimal geometric deformation approach, were satisfied. Hence, the anisotropic field equations were isolated resulting in a more treatable set of equations. The simplicity of the equations allows one to manipulate the anisotropies that can be implemented in a systematic way to obtain different realistic models for anisotropic configurations. Later on, the observational effects of such anisotropies when measuring the surface redshift were discussed. To conclude, the consistency of the application of the method over the obtained anisotropic configurations was shown. In this manner, different anisotropic sectors can be isolated from each other and modeled in a simple and systematic way. About 70% of the Universe is Dark Energy, but there is still no consensus in the physics community on what the nature of it is. Delta Gravity (DG) is an alternative theory of gravitation that could solve this cosmological problem. DG is able to explain the SNe data successfully. In this work, we explored the cosmological fluctuations that give rise to the CMB through a hydrodynamic approximation. We calculated the gauge transformations for the metric and the perfect fluid to present the equations of the evolution of cosmological fluctuations, providing the necessary equations to solve, in a semi-analytical way, the scalar TT Power Spectrum. These equations were useful for comparing the DG theory with astronomical observations and thus, being able to restrict the DG cosmology, testing the compatibility with the CMB Planck data, which are currently in contradiction with SNe data.
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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Browsing 3.10 Facultad de Física by Author "Alfaro Solís, Jorge Luis"

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