Finalized PhD theses

Number of entries: 82

Cosmological perturbation theory and the spherical collapse model

Status: defended (30/06/1998)
Student: Pablo Fosalba Vela
Supervised by: Enrique Gaztañaga ; Emilio Elizalde
University: Universitat de Barcelona

We present a simple and intuitive approximation for solving perturbation theory (PT) of small cosmic fluctuations. We consider only the spherically symmetric or monopole contribution to the PT integrals, which yields the exact result for tree-graphs (i.e. at leading order). We find that the non-linear…
Status: defended (30/06/1998)
Student: Pablo Fosalba Vela
Supervised by: Enrique Gaztañaga ; Emilio Elizalde
University: Universitat de Barcelona

We present a simple and intuitive approximation for solving perturbation theory (PT) of small cosmic fluctuations. We consider only the spherically symmetric or monopole contribution to the PT integrals, which yields the exact result for tree-graphs (i.e. at leading order). We find that the non-linear evolution in Lagrangian space is then given by a simple local transformation over the initial conditions, although it is not local in Euler space. This transformation is found to be described the spherical collapse (SC) dynamics, as it is the exact solution in the shearless (and therefore local) approximation in Lagrangian space. Taking advantage of this property, it is straightforward to derive the one-point cumulants, for both the unsmoothed and smoothed density fields to arbitrary order in the perturbative regime. To leading order this reproduces, and provides with a simple explanation for, the exact results obtained by Bernardeau (1992, 1994). We then show that the SC model leads to accurate estimates for the next corrective terms when compared to the results derived in the exact perturbation theory making use of the loop calculations (Scoccimarro & Frieman 1996). The agreement is within a few per cent for the hierarchical ratios $S_J$. We compare our analytic results to N-body simulations, which turn out to be in very good agreement up to scales where $\sigma \approx 1$. A similar treatment is presented to estimate higher order corrections in the Zel'dovich approximation. These results represent a powerful and readily usable tool to produce analytical predictions to describe the gravitational clustering of large scale structure in the weakly non-linear regime.

Search for monochromatic GW signals in data from the antenna EXPLORER

Status: defended (17/04/1998)
Student: Miquel Montero Torralbo
Supervised by: José Alberto Lobo Gutiérrez
University: Universitat de Barcelona

This Thesis is about the design and development of various filtering strategies for the analysis of data generated by a resonant bar gravitational wave (GW) antenna, with the goal to assess the presence (or absence) therein of long-duration monochromatic GW signals, as well as the eventual amplitude…
Status: defended (17/04/1998)
Student: Miquel Montero Torralbo
Supervised by: José Alberto Lobo Gutiérrez
University: Universitat de Barcelona

This Thesis is about the design and development of various filtering strategies for the analysis of data generated by a resonant bar gravitational wave (GW) antenna, with the goal to assess the presence (or absence) therein of long-duration monochromatic GW signals, as well as the eventual amplitude and frequency of the signals, within the sensitivity band of the detector. Such signals are most likely generated in the fast rotation of slightly asymmetric spinning stars. We develop practical procedures, together with a study of their statistical properties, which provide us with useful information on the performance of each technique. The selection of candidate events is then established according to threshold-crossing probabilities, based on the Neyman­-Pearson criterion. In particular, it is shown that this approach, based on phase estimation, presents a better signal-to-noise ratio than does pure spectral analysis, the most common approach. The methodology is applied and validated with data from the real GW detector EXPLORER, kindly provided by the Frascati (near Rome) Group, who designed, built and run the detector.

Spherical GW detectors

Status: defended (17/03/1997)
Student: Jose Antonio Ortega Ruiz
Supervised by: José Alberto Lobo Gutiérrez
University: Universitat de Barcelona

Shortly available
Status: defended (17/03/1997)
Student: Jose Antonio Ortega Ruiz
Supervised by: José Alberto Lobo Gutiérrez
University: Universitat de Barcelona

Shortly available

Thermonuclear burning on top of accreting white dwarfs

Status: defended (22/07/1996)
Student: José, J.
Supervised by: Margarita Hernanz Carbó
University: Universitat de Barcelona

To be introduced shortly
Status: defended (22/07/1996)
Student: José, J.
Supervised by: Margarita Hernanz Carbó
University: Universitat de Barcelona

To be introduced shortly

Structure and evolution of stars in the low main sequence

Status: defended (01/02/1994)
Student: Aparicio, J. M.
Supervised by: Jordi Isern Vilaboy
University: Universitat de Barcelona

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Status: defended (01/02/1994)
Student: Aparicio, J. M.
Supervised by: Jordi Isern Vilaboy
University: Universitat de Barcelona

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Calibraciones Ionosféricas en geodesia Espacial mediante el uso de datos GPS

Status: defended (01/03/1993)
Student: Ester sardón Pérez
Supervised by: Antonio Rius Jordán
University: Universidad Complutense de Madrid

Calibraciones Ionosféricas en geodesia Espacial mediante el uso de datos GPS
Status: defended (01/03/1993)
Student: Ester sardón Pérez
Supervised by: Antonio Rius Jordán
University: Universidad Complutense de Madrid

Calibraciones Ionosféricas en geodesia Espacial mediante el uso de datos GPS

Estudio de movimientos relativos en Europa mediante una red de radiointerferometría geodésica

Status: defended (01/11/1992)
Student: Nestor Zarraoa López
Supervised by: Antonio Rius Jordán
University: Universidad Complutense de Madrid

Estudio de movimientos relativos en Europa mediante una red de radiointerferometría geodésica
Status: defended (01/11/1992)
Student: Nestor Zarraoa López
Supervised by: Antonio Rius Jordán
University: Universidad Complutense de Madrid

Estudio de movimientos relativos en Europa mediante una red de radiointerferometría geodésica

Nucleosintesis y curvas de luz de las supernovas de tipo Ia

Status: defended (01/02/1991)
Student: Bravo, E.
Supervised by: Jordi Isern Vilaboy
University: Universitat de Barcelona

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Status: defended (01/02/1991)
Student: Bravo, E.
Supervised by: Jordi Isern Vilaboy
University: Universitat de Barcelona

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Modelos de curva de luz de las supernovas de tipo Ia

Status: defended (01/02/1991)
Student: Domínguez, I.
Supervised by: Jordi Isern Vilaboy
University: Universitat de Barcelona

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Status: defended (01/02/1991)
Student: Domínguez, I.
Supervised by: Jordi Isern Vilaboy
University: Universitat de Barcelona

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El diagrama de fases del plasma de carbono-oxígeno y la función de luminosidad de las enanas blancas

Status: defended (01/02/1990)
Student: García-Berro, E.
Supervised by: Jordi Isern Vilaboy
University: Universitat de Barcelona

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Status: defended (01/02/1990)
Student: García-Berro, E.
Supervised by: Jordi Isern Vilaboy
University: Universitat de Barcelona

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