Finalized Master theses

Número de entradas: 37

Critical phenomena in gravitational collapse. Study in asymptotically Minkowski and Anti-de Sitter space-times

Estado: defended (12/09/2013)
Estudiante: Daniel Santos Oliván
Supervisada por: Carlos Sopuerta
Universidad: Universitat de Barcelona

We are going to use numerical relativity to focus in the problem of gravitational collapse of a scalar field. The rest chapter of this thesis is dedicated to the classical Choptuik's problem of gravitational collapse in asymptotically flat spacetime. In the second chapter, we try to address a more…
Estado: defended (12/09/2013)
Estudiante: Daniel Santos Oliván
Supervisada por: Carlos Sopuerta
Universidad: Universitat de Barcelona

We are going to use numerical relativity to focus in the problem of gravitational collapse of a scalar field. The rest chapter of this thesis is dedicated to the classical Choptuik's problem of gravitational collapse in asymptotically flat spacetime. In the second chapter, we try to address a more contemporary problem as the gravitational collapse in asymptotically Anti-de Sitter spacetime.

Development of the Detector Tray for the Wide Field Monitor of the Large Observatory For x-ray Timing (LOFT), a medium-class candidate mission in ESA´s Cosmic Vision 2015-2025

Estado: defended (15/07/2013)
Estudiante: Dmitri Karelin
Supervisada por: Margarita Hernanz
Universidad: Universitat Politècnica de Catalunya

LOFT, the Large Observatory For X-ray Timing, has recently pass the ESA call as one of the four M3 mission candidates that will compete for a launch opportunity at the start of the 2020s. The primary goal of the mission is to study strong-field gravity, black hole masses and spins, and the…
Estado: defended (15/07/2013)
Estudiante: Dmitri Karelin
Supervisada por: Margarita Hernanz
Universidad: Universitat Politècnica de Catalunya

LOFT, the Large Observatory For X-ray Timing, has recently pass the ESA call as one of the four M3 mission candidates that will compete for a launch opportunity at the start of the 2020s. The primary goal of the mission is to study strong-field gravity, black hole masses and spins, and the equation of state of ultra-dense matter via high-time-resolution Xray observations of compact objects. Two instruments will be comprised in the scientific payload of LOFT: the Large Area Detector (LAD) a 12 m2 collimated X-ray detector in the 2-80 keV range, with unprecedented timing capabilities, and the Wide Field Monitor (WFM), a coded-mask wide field X-ray monitor. Both instruments are based on silicon drift detectors. The main scope of WFM is catch good triggering sources to be pointed with LAD. LOFT’s Wide Field Monitor (WFM) will discover and localize X-ray transients and impulsive events and monitor spectral state changes with unprecedented sensitivity, providing interesting targets for LAD's pointed observations. The working principle of the WFM is the classical sky encoding by coded masks and is widely used in space borne instruments (e.g. INTEGRAL, RXTE/ASM, Swift/BAT). The mask shadow recorded by the position-sensitive detector can be de-convolved by using the proper procedures to recover the image of the sky, with an angular resolution given by the ratio between the mask element size and the mask-detector distance. By using Silicon Drift Detectors (SDDs), with a position resolution

The dynamic behavior and modeling of meteors using the Runge-Kutta algorithm

Estado: defended (11/07/2013)
Estudiante: Joan Dergham
Supervisada por: Josep M. Trigo-Rodríguez
Universidad: Universitat Autònoma de Barcelona

The goal of this master thesis is developing a model to describe the behavior of the meteors during atmospheric deceleration. The process is studied in the framework of the mass drag-loss equations or so-called single body theory which was first described by Brohnsten (1983). The drag-loss equations…
Estado: defended (11/07/2013)
Estudiante: Joan Dergham
Supervisada por: Josep M. Trigo-Rodríguez
Universidad: Universitat Autònoma de Barcelona

The goal of this master thesis is developing a model to describe the behavior of the meteors during atmospheric deceleration. The process is studied in the framework of the mass drag-loss equations or so-called single body theory which was first described by Brohnsten (1983). The drag-loss equations are introduced in a differential form, and depend on parameters like the shape, the density, the initial mass, the ablation coefficient and others. By fitting the curve created by the differential equations to the observational data obtained from multiple-station camera recordings, all these parameters can be obtained. Then, we expect to achieve a better understanding of the meteoroid interaction and the formation of meteors. Basically we will study how the meteoroid decelerates and penetrates into the atmosphere. In particular we will study the entry and ablation model of Chelyabinsk  asteroid.

Implications for compact stars of a nuclear equation-of-state constrained from heavy ion collisions

Estado: defended (02/07/2012)
Estudiante: Eduard Bosch Coch
Supervisada por: Laura Tolos
Universidad: Universitat de Barcelona

Measurements of kaon production at subthreshold energies in heavy-ion collisions point to a soft nuclear equation of state for densities up to two to three times nuclear matter saturation density. We apply these results to study the implications on compact star properties, especially in the context…
Estado: defended (02/07/2012)
Estudiante: Eduard Bosch Coch
Supervisada por: Laura Tolos
Universidad: Universitat de Barcelona

Measurements of kaon production at subthreshold energies in heavy-ion collisions point to a soft nuclear
equation of state for densities up to two to three times nuclear matter saturation density. We apply these results
to study the implications on compact star properties, especially in the context of the recent measurement of
the two solar mass pulsar PSR J1614-2230. The implications are twofold: First, the heavy-ion results constrain
nuclear matter at densities relevant to light neutron stars. Hence, a radius measurement could provide information
about the density dependence of the symmetry energy which is a crucial quantity in nuclear physics. Second,
the information on the nucleon potential obtained from the analysis of the heavy-ion data can be combined with
restrictions from causality on the nuclear equation of state. From this we can derive a limit for the highest allowed
compact star mass of three solar masses.

An analytical Model of Accretion onto White Dwarfs

Estado: defended (20/06/2012)
Estudiante: Nataly Ospina Escobar
Supervisada por: Margarita Hernanz
Universidad: Universitat Autònoma de Barcelona

Accretion in white dwarf systems can occur through discs, accretion columns or directly onto the magnetic poles, depending of the magnetic field of the white dwarf. A white dwarf accretes matter from a companion star (typically a red dwarf) that fills its Roche lobe. This matter forms an accretion…
Estado: defended (20/06/2012)
Estudiante: Nataly Ospina Escobar
Supervisada por: Margarita Hernanz
Universidad: Universitat Autònoma de Barcelona

Accretion in white dwarf systems can occur through discs, accretion columns or directly onto the magnetic poles, depending of the magnetic field of the white dwarf. A white dwarf accretes matter from a companion star (typically a red dwarf) that fills its Roche lobe. This matter forms an accretion disc inside the Roche lobe of the WD. The disc, however, is disrupted by the WD magnetic field at some distance from the WD surface. As a result the accreting matter freely falls on to the WD surface and forms a strong shock near its surface. The post-shock matter has a high temperature and emits X-rays. The temperature of the post-shock matter depends on the WD mass and, therefore, the X-ray spectra can be used for WD mass determination. The purpose of this work is study the structure of the emission region (temperature, density and gas velocity distributions) and to calculate the X-ray spectrum of the thermal bremsstrahlung from this region.

Studying Martian meteorites: looking for clues on Mars

Estado: defended (13/06/2012)
Estudiante: Carles Eduard Moyano Cambero
Supervisada por: Josep M. Trigo-Rodríguez
Universidad: Universitat Autònoma de Barcelona

Some achondrites, differentiated meteorites, were suggested to be originated in Mars, but reasonable doubt persisted for decades. Fortunately in 1983 Bogard and Johnson noticed that the meteorite Elephant Moraine 79001 contained very small amounts of trapped gases within shock glass veins in the same…
Estado: defended (13/06/2012)
Estudiante: Carles Eduard Moyano Cambero
Supervisada por: Josep M. Trigo-Rodríguez
Universidad: Universitat Autònoma de Barcelona

Some achondrites, differentiated meteorites, were suggested to be originated in Mars, but reasonable doubt persisted for decades. Fortunately in 1983 Bogard and Johnson noticed that the meteorite Elephant Moraine 79001 contained very small amounts of trapped gases within shock glass veins in the same proportion that they were measured by the Viking spacecraft in Mars’ atmosphere. Consequently, the scientific community realized that meteoritics, the branch of astronomy and cosmochemistry that studies meteorites, was completely necessary to increase our knowledge of the planet. Martian meteorites are an available source of samples from the red planet to be studied in terrestrial laboratory; in fact, they are the only samples available by now. Consequently, the main goals of this master work are:
1. To explain the main analytical techniques capable to identify Martian meteorites in terrestrial laboratories. This includes applying some of them to which we have direct access.
2. Martian meteorites are strongly affected by shock as they are delivered to Earth after colossal impacts with asteroids that impulse surface rocks with enough kinetic energy to escape of Mars’ gravity field. Understanding the impact effects on their constitutive minerals, and knowing the minerals typically produced by shock is necessary to obtain right conclusions on the real Mars mineralogy.
3. To describe the main clues obtained on Mars atmospheric evolution by using the data already obtained on the basis of the implanted gas in SNC meteorite glasses.    

Bulk viscosities of color-flavor quark matter

Estado: defended (31/03/2011)
Estudiante: Robert Bierkandt
Supervisada por: Cristina Manuel Hidalgo

We evaluate the three bulk viscosity coefficients $\zeta_1, \zeta_2$ and $\zeta_3$ in the color-flavor locked (CFL) superfluid phase due to phonons and kaons, which are the lightest modes in that system. We first show that the computation is rather analogous to the computation of the same coefficients…
Estado: defended (31/03/2011)
Estudiante: Robert Bierkandt
Supervisada por: Cristina Manuel Hidalgo

We evaluate the three bulk viscosity coefficients $\zeta_1, \zeta_2$ and $\zeta_3$ in the color-flavor locked (CFL) superfluid phase due to phonons and kaons, which are the lightest modes in that system. We first show that the computation is rather analogous to the computation of the same coefficients in superfluid $^4$He, as due to phonons and rotons. For astrophysical applications, we also find the value of the viscosities when there is a periodic disturbance, and the viscosities also depend on the frequency of the disturbance. In a temperature regime that might be of astrophysical relevance, we find that the contributions of both the phonons and kaons should be considered, and that $\zeta_2$ is much less that the same coefficient in unpaired quark matter.

Study of the mechanical response of the LTP's test masses due to the action of control heaters in LISA Pathfinder

Estado: defended (25/02/2011)
Estudiante: Ferran Gibert Gutiérrez
Supervisada por: José Alberto Lobo Gutiérrez; Chester, E.
Universidad: Universitat Politècnica de Catalunya

The main aim of the LISA Pathfinder (LPF) mission is to place two Test Masses into a very stable drag free environment and make very precise interferometric measurements of displacements between them. In order to achieve such an objective, it is necessary to characterize and model the disturbances that…
Estado: defended (25/02/2011)
Estudiante: Ferran Gibert Gutiérrez
Supervisada por: José Alberto Lobo Gutiérrez; Chester, E.
Universidad: Universitat Politècnica de Catalunya

The main aim of the LISA Pathfinder (LPF) mission is to place two Test Masses into a very stable drag free environment and make very precise interferometric measurements of displacements between them. In order to achieve such an objective, it is necessary to characterize and model the disturbances that will appear. Amongst the different physical effects that will appear onboard, temperature fluctuations in the Electrode Housing (EH) generate disturbances on the interferometer (IFO) readouts, therefore they must be known and controlled. Consequently, a simulator of the whole LPF is being developed to provide a validation tool for the mission operations tele-commanding chain, as well as for a deeper understanding of the underlying physical processes happening in the LTP (LISA Technology Package), the instrument hosting the Test Masses. In this study, the whole algorithm required to calculate the forces and torques on the Test Masses due to the activation of the different LTP control heaters is detailed. More specifically, transfer functions relating heat input signals to temperature increments on the Test Masses (TMs) in the LTP frequency band, from 1 mHz to 30 mHz, are determined. Following, the EH environment is studied and discretised to calculate the forces and torques that appear through thermal effects (radiometer effect, radiation pressure effect, etc). Finally, the algorithm is implemented and some experiments from the EMP (Experiment Master Plan) are simulated to evaluate the associated dynamical effects on the Test Masses. A complete thermal model of the entire LPF spacecraft plus payload, elaborated and maintained at European Space Technology Centre (ESTEC), was used to obtain temperature distributions in response to heat inputs at prescribed spots (heaters).

Jet energy loss in the quark-gluon plasma by stream instabilities

Estado: defended (17/02/2011)
Estudiante: Gonzalez-Solis, S
Supervisada por: Cristina Manuel Hidalgo
Universidad: Universitat Autònoma de Barcelona

We study the evolution of the plasma instabilities induced by two jets of particles propagating in opposite directions and crossing a thermally equilibrated non-Abelian plasma. In order to simplify the analysis we assume that the two jets of partons can be described with uniform distribution functions…
Estado: defended (17/02/2011)
Estudiante: Gonzalez-Solis, S
Supervisada por: Cristina Manuel Hidalgo
Universidad: Universitat Autònoma de Barcelona

We study the evolution of the plasma instabilities induced by two jets of particles propagating in opposite directions and crossing a thermally equilibrated non-Abelian plasma. In order to simplify the analysis we assume that the two jets of partons can be described with uniform distribution functions in coordinate space and by Gaussian distribution functions in momentum space. We find that while crossing the quark-gluon plasma, the jets of particles excite unstable chromomagnetic and chromoelectric modes. These fields interact with the particles (or hard modes) of the plasma inducing the production of currents; thus, the energy lost by the jets is absorbed by both the gauge fields and the hard modes of the plasma. We compare the outcome of the numerical simulations with the analytical calculation performed assuming that the jets of particles can be described by a tsunami-like distribution function. We find qualitative and semi-quantitative agreement between the results obtained with the two methods

Propietats del sistema binari eclipsant V402 Lac

Estado: defended (28/01/2010)
Estudiante: Enrique Herrero Casas
Supervisada por: Jordi C.; Francesc Vilardell Sallés; Ignasi Ribas Canudas
Universidad: Universitat de Barcelona

Eclipsing binary (EB) systems showing double lines in their spectra are excellent sources of knowledge about structure and evolution of stars. The analysis of photometric and spectroscopic data in such double systems provides very accurate values for the absolute properties of both stars, as well as…
Estado: defended (28/01/2010)
Estudiante: Enrique Herrero Casas
Supervisada por: Jordi C.; Francesc Vilardell Sallés; Ignasi Ribas Canudas
Universidad: Universitat de Barcelona

Eclipsing binary (EB) systems showing double lines in their spectra are excellent sources of knowledge about structure and evolution of stars. The analysis of photometric and spectroscopic data in such double systems provides very accurate values for the absolute properties of both stars, as well as clues about their internal structure, their formation process and the possible existence of other bodies altering their motion. V402 Lac is a V=6.7 mag binary system with two B9 type stars at a distance of 240 pc from the Sun, classified as an Algol-type EB since Hipparcos observations. In our work we are using light curves and radial velocity data in order to obtain the parameters of the binary system through an analysis with the Wilson-Devinney (WD) code. The first results, using independently the two types of data, show a clear discrepancy in some orbital parameters, which is also reproduced by new observations. Our study also revealed the existence of apsidal movement in the system, and all the times of minima are being used in order to characterize it through an O-C diagram. We are dealing with a very interesting EB with no solution for the moment. The photometrical observations scheduled for late 2010 can be decisive to solve the orbit of the system and then be able to obtain accurate values of the physical properties of the stars.
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An institute of the Consejo Superior de Investigaciones Científicas

An institute of the Consejo Superior de Investigaciones Científicas
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