Geometrical scalar back-reaction effects in inflation

Starting with the Lagrangian formulation of General Relativity, we will conduct an investigation into the production of spacetime waves, due to a geometric boundary term of a closed extended manifold, within the tensor and scalar sectors. This scheme will be studied in an inflationary universe. We explore two distinct scenarios: Cold Inflation and Warm Inflation. The scalar modes $Z_{k}^{\mathbb{R}}$ and $Z_{k}^{\mathbb{I}}$ oscillate within the horizon, and they become constant at (or right after) horizon crossing $k\simeq aH$ and they remain so when radiation starts to dominate. The larger $k/k_{0}$ the $Z_{k}$'s amplitudes increase too. In general we can notice that radiation reduces the size of the $Z_{k}$'s amplitudes, hence yielding smaller signals of such modes. The tensor sector shows an irregular journey due to their abruptly growth just as they cross the horizon. This upshot hinders any probable observational hint or signal. However, we expect this novel mechanism of spacetime waves production brings new cosmological sources, for which no astrophysical source has been identified.Comment: 21 pages, 10 figure

Consequences of dissipative dynamics in the early universe

Warm inflation presents an exceptional description of the early universe cosmology. It is a scenario of an inflationary dynamics in which the state of the universe during inflation is not the vacuum state, but rather an excited statistical thermal state. It introduces dissipation into the inflationary dynamics which can be well explained by first principles of a quantum multi-field theory. Besides, this approach has several attractive features. For instance, the additional friction may ease the required flatness of the inflaton potential. Besides, even if radiation is subdominant during inflation, may smoothly become the leading component if the ratio of dissipation Q ≳ 1 at the end of inflation (ϵeff ~ 1 + Q), with no need for a separate reheating period. It also may explain the nature of the classical inhomogeneities observed in the CMB, since for WI the fluctuations of the inflaton are thermally induced; hence there is no need to explain the troublesome quantum-to-classical transition problem of the standard inflation picture, cold inflation, due to the purely quantum origin of the density perturbations. Furthermore, one well established key aspect is the prediction for a low tensor-to-scalar ratio, which now we see is consistent with Planck legacy. Taking into account above encouraging warm inflation characteristics, in this thesis we will describe both warm inflation model building and the confrontation of theory with observation. We will examine two basic models: The Warm Little Inflaton scenario and the distributed mass model. In each case, we determine the parametric regimes in which the dynamical evolution is consistent for 50-60 e-folds of inflation, taking into account thermal corrections to the scalar potential (if necessary). In the first model we consider three distinct types of scalar potentials for the inflaton, namely chaotic inflation with a quartic monomial potential, a Higgs-like symmetry breaking potential and a non-renormalizable plateau-like potential. On the other hand, the distributed mass model is examined for various mass distributions considering a chaotic quartic potential. Both scenarios are theoretically and observationally successful for a broad range of parameter values. Indeed, they agree remarkably with the Planck legacy data. The Warm Little Inflaton is undoubtedly the simplest realisation of warm inflation within a concrete quantum field theory construction, since it requires only a small number of fields; in particular, the inflation is directly coupled to just two light fields. Distributed mass models can be viewed as realisations of the landscape property of string theory, with the mass distributions coming from the underlying spectra of the theory, which themselves would be affected by the vacuum of the theory

Post-Newtonian Gravitational Waves with cosmological constant Λ\Lambda from the Einstein-Hilbert theory

We study the Post-Newtonian approach implemented to the Einstein-Hilbert action adding the cosmological constant $\Lambda$ at 1PN order. We consider very small values of $\Lambda$ to derive the Lagrangian of a two body compact system at the center of mass frame at 1PN. Furthermore, the phase function $\phi(t)$ is obtained from the balance equation and the two polarizations $h_{+}$ and $h_{\times}$ are also calculated. We observe changes due to $\Lambda$ only at very low frequencies and we notice that it plays the role of "stretch" the spacetime such that both amplitudes become smaller; however, given its nearly negligible value, $\Lambda$ has no relevance at higher frequencies whatsoever.Comment: 20 pages, 7 figure

Classical and quantum exact solutions for a FRW multi-scalar field cosmology with an exponential potential driven inflation

A flat Fiedmann-Robertson-Walker (FRW) multi-scalar field cosmology is studied with a particular potential of the form $\rm V(\phi,\sigma)=V_0 e^{-\lambda_1 \phi-\lambda_2 \sigma}$, which emerges as a relation between the time derivatives of the scalars field momenta. Classically, by employing the Hamiltonian formalism of two scalar fields $\rm(\phi,\sigma)$ with standard kinetic energy, exact solutions are found for the Einstein-Klein-Gordon (EKG) system for different scenarios specified by the parameter $\rm\lambda^2=\lambda_1^2+\lambda_2^2$, as well as the e-folding function $\rm N_{e}$ which is also computed. For the quantum scheme of this model, the corresponding Wheeler-DeWitt (WDW) equation is solved by applying an appropriate change of variables.Comment: Latex file, accepted in Advances and Mathematical physics, Hindawi. arXiv admin note: text overlap with arXiv:1806.0119

Estudio de potencial turístico en el municipio del Guamo Bolívar /

El municipio del Guamo Bolívar cuenta con unas características naturales y socioculturales increíbles las cuales aún no han sido descubiertas por la gente que viven en la capital del departamento y/o llegan al departamento de Bolívar. La falta de interés y el estigma que ha vivido la zona por efectos de un pasado que ha quedado atrás, ha hecho de este municipio un lugar con potencial turístico que aún está sin explotar. El ejercicio de la actividad turística podría beneficiar a la región y a sus habitantes, que en el momento viven la falta de progreso a causa de su economía rezagada, a pesar de ser uno de los municipios con menores necesidades básicas insatisfechas en la región de Montes de María. No obstante, es un municipio de grandes disparidades, en las que unos pocos propietarios son dueños de grandes extensiones de tierra y han jalonado el desarrollo del Guamo, pero a la vez, más del 95% de los pobladores pertenecen al SISBEN 1 y 2, indicando las precarias condiciones en las que viven. Infortunadamente, este no es el único caso que en Colombia se presenta, son muchos pueblos que viven el mismo retraso y abandono. Con este trabajo se busca pensar en alternativas no solo para los residentes del Guamo sino también para los visitantes que llegan a Cartagena en busca de conocimiento cultural y actividades ecológicas; para de esta forma promoverse un desarrollo económico, social y cultural en beneficio de propios y foráneos. Todo ello, aprovechando por un lado, la demanda que existe por planes turísticos de carácter ecológico y cultural, y por otro, la riqueza en cuanto a los activos naturales y culturales que tiene este municipio, los cuales como se observará en el capítulo de Inventario Turístico son varios, develando un gran potencial en esta región que le ayudaría a salir adelante. Por esto, es importante la redirección o reforma de políticas de desarrollo e invertir en el capital humano de este pueblo para que en un futuro toda la población se convierta en una comunidad próspera y enmarcada en una senda de desarrollo a largo plazoIncluye bibliografí

Cosmological Boundary Flux Parameter

The {\it{Cosmological Boundary Flux Parameter}} is a novel proposal that attempts to explain the origin of the cosmological parameter $\Lambda$ purely by geometric nature. Then we implement this new approach to a flat FLRW universe along with a barotropic fluid. We present an ansatz in which $\Lambda$ is straightforwardly coupled to the matter sector; therefore, only one additional parameter was introduced: $\lambda$. Also, through a statistical analysis, using late-time data of observational Hubble and type Ia Supernovae, we computed the joint best-fit value of the free parameters by means of the affine-invariant MCMC. We want to emphasise that the joint analysis produces a smaller $H_{0}^{\rm CBFP}=69.80\rm\,\, Km \,s^{-1}\,Mpc^{-1}$ in contrast to the flat $\Lambda$CDM result $H_{0}^{\Lambda\rm CDM}=70.53\rm\,\, Km \,s^{-1}\,Mpc^{-1}$. The work presented here seeks to contribute to the discussion of the possible explanation for the cosmos' acceleration, together with tackling other important questions in modern cosmology.Comment: 15 pages, 6 figure

Emission of spacetime waves from the partial collapse of a compact object

In this work we describe the partial collapse of a compact object and the emission of spacetime waves as a result of back-reaction effects. As a source mass term we propose a non-smooth continuous function that describes a mass-loss, and we then obtain the solution of such setting. We present three distinct examples of the evolution of the norm $|R_{nl}(t,r_{*})|$ in terms of $t$, and four different results are shown for the parameter $l=1,2,5,10$; here $r_{*}$ is the fixed radius of an observer outside the compact object. In all cases, the decay behaviour is actually present at $t\gg 1$ and becomes more evident for larger $l$. In addition, for the results that have smaller $l$'s their amplitudes are larger when the asymptotic character of $|R_{nl}(t,r_{*})|$ clearly appears. Finally, the farther away an observer is set, the fewer oscillations are perceived; however, from our particular fixed set of parameters, the best spot to observe the wiggles of the emitted spacetime waves is close to $r_{*}\simeq \alpha$.Comment: 8 pages, 3 figure

Using oceanography to control and forecast nuclear accidents and other passive particles problems

This article is the last improved version of a previously published model (Toscano-Jimenez and Garcia-Tenorio, 2004) for the transport of the nuclear contamination and other passive particles in the ocean. Two interesting advances have been developed during last two years for the author's PhD thesis to be finished in the next months: (a) a suspended particulate matter (SPM) submodel, including erosion, transport and sedimentation. (b) A new advection-diffusion approach with numerical and computational improvements: finite elements (FE), finite differences (FD) and Monte Carlo (MC) methods have been compared and calibrated. The Baltic Sea has been elected as the validation scenario of the model and the radioisotope 137 Cs is the radiotracer to be analysed. This scenario was the most contaminated ecosystem out of the Soviet Union due to the Chernobyl accident which occurred at the end of April 1986, and the elected radiotracer 137 Cs was the main long-lived radioisotope emitted to the environment. However, an important aim of this model is its potential usefulness in other oceanic scenarios affected by a nuclear disaster in the future. It could be an interesting tool to predict and minimize the ecological and economical impacts of future accidents. This model can also be extended easily to non-nuclear contamination problems such as: oil accidents, nutrients dynamics and other biological problems

The impact of mind on nature. Lessons learned from the ecology-aesthetics interplay

The effects of nature on people's mind have been an active research theme for decades. However, the impact of people's mind on landscape ecological health has received less attention. How and why perception, meanings and mental constructs determine the way nature is valued and consequently managed? How this interplay should be? These are in some cases more relevant questions than knowing what particular landscapes are preferred (Carlson 1993). This was the underlying inquiry in the focus group experience held in a natural protected area in La Rioja (Spain). Participants were asked to locate in a map areas representing low/high quality in terms of ecology and aesthetics. Some relevant conclusions for landscape management were derived from the analysis of participant's discourse in terms of ecological aesthetical appreciation and their consideration about how human takes place in nature