Finalized Master theses

Nombre d'entrades: 54

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

Estat: defended (02/07/2012)
Estudiant: Eduard Bosch Coch
Supervisat per: Laura Tolos
Universitat: 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…
Estat: defended (02/07/2012)
Estudiant: Eduard Bosch Coch
Supervisat per: Laura Tolos
Universitat: 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

Estat: defended (20/06/2012)
Estudiant: Nataly Ospina Escobar
Supervisat per: Margarita Hernanz Carbó
Universitat: 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…
Estat: defended (20/06/2012)
Estudiant: Nataly Ospina Escobar
Supervisat per: Margarita Hernanz Carbó
Universitat: 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

Estat: defended (13/06/2012)
Estudiant: Carles Eduard Moyano Cambero
Supervisat per: Josep M. Trigo-Rodríguez
Universitat: 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…
Estat: defended (13/06/2012)
Estudiant: Carles Eduard Moyano Cambero
Supervisat per: Josep M. Trigo-Rodríguez
Universitat: 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

Estat: defended (31/03/2011)
Estudiant: Robert Bierkandt
Supervisat per: 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…
Estat: defended (31/03/2011)
Estudiant: Robert Bierkandt
Supervisat per: 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

Estat: defended (25/02/2011)
Estudiant: Ferran Gibert Gutiérrez
Supervisat per: José Alberto Lobo Gutiérrez; Chester, E.
Universitat: 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…
Estat: defended (25/02/2011)
Estudiant: Ferran Gibert Gutiérrez
Supervisat per: José Alberto Lobo Gutiérrez; Chester, E.
Universitat: 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

Estat: defended (17/02/2011)
Estudiant: Gonzalez-Solis, S
Supervisat per: Cristina Manuel Hidalgo
Universitat: 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…
Estat: defended (17/02/2011)
Estudiant: Gonzalez-Solis, S
Supervisat per: Cristina Manuel Hidalgo
Universitat: 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

Estat: defended (28/01/2010)
Estudiant: Enrique Herrero Casas
Supervisat per: Jordi C.; Francesc Vilardell Sallés; Ignasi Ribas Canudas
Universitat: 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…
Estat: defended (28/01/2010)
Estudiant: Enrique Herrero Casas
Supervisat per: Jordi C.; Francesc Vilardell Sallés; Ignasi Ribas Canudas
Universitat: 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.

A New Method to Simulate Extreme-Mass-Ratio Inspirals for the Laser Interferometer Space Antenna

Estat: defended (20/04/2009)
Estudiant: Priscil·la Cañizares Martínez
Supervisat per: Carlos Sopuerta
Universitat: Universitat Autònoma de Barcelona

In this work we are going to study a model of the most promising sources of GWs for LISA. These are the systems made up of an stellar compact object (SCO), m = 1 -􀀀 5 0Msun, inspiralling into a massive black hole (MBH), M = 104 - 107 Msun. These systems are called Extreme Mass-Ratio Inspirals (EMRIs)…
Estat: defended (20/04/2009)
Estudiant: Priscil·la Cañizares Martínez
Supervisat per: Carlos Sopuerta
Universitat: Universitat Autònoma de Barcelona

In this work we are going to study a model of the most promising sources of GWs for LISA. These are the systems made up of an stellar compact object (SCO), m = 1 -􀀀 5 0Msun, inspiralling into a massive black hole (MBH), M = 104 - 107 Msun. These systems are called Extreme Mass-Ratio Inspirals (EMRIs) due to the mass ratios involved are in the range q = m/M = 10-7 -􀀀  10-3.

X/Gamma-Ray spectroscopy signal processor using LabView

Estat: defended (07/02/2008)
Estudiant: Nil García Garcia
Supervisat per: Margarita Hernanz Carbó; José Manuel Álvarez Pastor
Universitat: Universitat Politècnica de Catalunya

X/Gamma-Ray spectroscopy signal processor using LabView
Estat: defended (07/02/2008)
Estudiant: Nil García Garcia
Supervisat per: Margarita Hernanz Carbó; José Manuel Álvarez Pastor
Universitat: Universitat Politècnica de Catalunya

X/Gamma-Ray spectroscopy signal processor using LabView

Design, development, and field testing of a precise, ruggedized, autonomous, and low-cost GPS system for polar environments

Estat: defended (17/01/2008)
Estudiant: Ismael González Flores
Supervisat per: Pedro Elosegui Larrañeta
Universitat: Universitat Politècnica de Catalunya

Glaciers undergo a dynamic glacial response to changing climate conditions. This response of glaciers is critically important, but poorly understood. In order to improve the understanding of glacier dynamics, a high spatio-temporal resolution GPS network has been designed to monitor a glacier. It will…
Estat: defended (17/01/2008)
Estudiant: Ismael González Flores
Supervisat per: Pedro Elosegui Larrañeta
Universitat: Universitat Politècnica de Catalunya

Glaciers undergo a dynamic glacial response to changing climate conditions. This response of glaciers is critically important, but poorly understood. In order to improve the understanding of glacier dynamics, a high spatio-temporal resolution GPS network has been designed to monitor a glacier. It will be deployed in the Helheim Glacier, a fast-flowing outlet glacier located on East Greenland that drains its icebergs to the Atlantic Ocean. We have designed a GPS network composed of 30 GPS receiving systems (slaves) on the glacier surface and three masters on the glacier margins. We have designed a new GPS receiving system to operate on the ice at single frequency. The system is a precise, low cost, robust, and autonomous OEM application that, in its current stage, consists of: • GPS omnidirectional antenna: receives signals from all satellites above the antenna’s horizon. • GPS receiver board: stores code and phase data continuously at a sampling rate of one observation per second (1 Hz). • Interface Board: we have designed an interface board, named Gonzak Board, to control the entire system and to translate the raw files stored to a lower case format, Hatanaka-compressed, to reduce the air transmission time principally. • Radio modem: sends the Hatanaka-compressed files of each receiver to a master site at 2.4 GHz. • Communications antenna: is a transducer that works with the radio modem at 2.4 GHz. It transmits and receives electromagnetic waves, that is, converts electromagnetic waves into electrical currents and vice versa, in order to have communication between the GPS receiving system and the master site. • Polycrystalline Photovoltaic Panel: converts sunlight energy into electricity energy consuming no conventional fossil fuels, creating no pollution, and lasting for decades with very little maintenance. • Battery: is an energy storage to have at one’s disposal energy during night periods or with little solar irradiation (cloud or foggy days). • Charge controller: is located between the photovoltaic panels and the battery. It is used to prevent the battery bank from being overcharged when the battery is charged (measuring the battery voltage). Overcharging a battery shortens its life. Despite the long, dark Arctic winters, solar energy is considered the best current technology for our purpose. Strong, katabatic winds are known to have demolished wind generators in polar environments. The receiver data files are sent to a master site in Hatanaka-compressed format, and then, to a recipient via a satellite link for data post-processing. The GPS network combines the single frequency receiving systems on the ice with fixed dual frequency systems to mitigate the ionospheric effect on position estimations at the ice. Every day, the files created in a whole day at the 30 GPS receiving systems are downloaded via satellite from the head master (NUN1). We have studied the communications via Iridium satellites and designed the network to transmit via satellite, each day, only the Hatanaka-compressed files at 33.3 mHz to reduce the tranmission time of the satellite link. But, if something interesting occurs (e.g., a glacial earthquake) one specific day, the corresponding Hatanaka-compressed files will be downloaded at a higher temporal rate (1 Hz) to process data with increased temporal resolution. This can be performed automatically or by user request via satellite link. We have tested several components of this GPS receiving system at Helheim Glacier during the Summer of 2007. We have processed this data land demonstrated that the quality is similar to a high-precision, geodetic-type GPS receiver. We also tested communications with Intuicom’s radio modems. The GPS network will be developed by summer 2008. The low cost and autonomous GPS receiving system could be used in future expeditions and projects to study any topic linked or not with glaciology. The project had a good reception in the lectures made in the congress of San Franciscon on December 2007. As a consequence, currently, contacts with other research teams have contacted with us since they are interested in the design and manufacturing of similar precise system.
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An institute of the Consejo Superior de Investigaciones Científicas

An institute of the Consejo Superior de Investigaciones Científicas
Affiliated with the Institut d'Estudis Espacials de Catalunya

Affiliated with the Institut d'Estudis Espacials de Catalunya