Here you may find information on the **fellows of the PhD::SPACE **Program that have selected a topic on the thematic line on **Unveiling the dynamics of the Universe.**

**2016/B013 Fellow: Bruno J. C. B. de Barros **(*ongoing*)

**Fellowship: **PD/00040/2012 – PD/BD/128017/2016 - FCT

**Advisors: Nelson Nunes **(IA-U.Lisboa),** Ippocratis Saltas** (IA – U.Lisboa)

**PhD Topic (2016/424): Generalised Scalar-tensor Theories of Gravity in Cosmology**

This PhD project concerns the model building and associated phenomenology of gravitational theories beyond the standard paradigm of General Relativity, focusing on general theories constructed out of a scalar field, known as generalised scalar-tensor theories. The student will learn and apply analytical and numerical tools, such as cosmological perturbation theory and statistical methods to make phenomenological predictions for the dynamics and structure of the Universe at very large scales, with the aim of testing the concordance cosmological model with current and future observational surveys like Euclid and Planck. On the same time, the student will have the opportunity to explore the implications of these theories for the Universe at its very first moments after the Big Bang, where quantum-gravitational effects become important.

**University:** Lisboa

**Starting date:** 2016/10/01

**2016/B011 Fellow: Francisco T. O. Cabral **(*ongoing*)

**Fellowship: **PD/00040/2012 – PD/BD/128017/2016 - FCT

**Advisors: Francisco S. N. Lobo **(IA-U.Lisboa),** Diego Rubiera-Garcia** (IA – U.Lisboa)

**PhD Topic (2016/421): Late-time Cosmic Acceleration and Modified Theories of gravity**

The late-time cosmic accelerated expansion is one of the most important and challenging current problems in cosmology. Although models of dark energy are the most popular candidates responsible for the cosmic expansion, the latter may be due to modifications of General Relativity, which introduce new degrees of freedom to the gravitational sector itself. This research project will explore the viability of a plethora of modified gravity models, consistently analysing the reproduction of all the cosmological epochs. More specifically, we will consider generalizations of the Einstein- Hilbert action by including non-linear curvature invariants and Lagrangians that also include curvature couplings to the matter sector. Another class of theories under our scrutiny will be generalised scalar-tensor or vector-tensor gravity theories, where scalar or vector fields play gravitational roles that can also be perceived as couplings to matter in an appropriate frame. One fundamental goal of this project is to study the theoretical issues of the extra degrees of freedom of the theory and to analyse its astrophysical applications.

**University:** Lisboa

**Starting date:** 2016/10/01

**2015/B009 Fellow: Ana Catarina O. Leite **(*ongoing*)

**Fellowship: **PD/00040/2012 – PD/BD/113746/2015 - FCT

**Advisors: Carlos Martins **(IA-U.Porto),** Paolo Molaro** (INAF Trieste)

**PhD Topic (2015/410c): The ESPRESSO Road to Fundamental Cosmology**

The full cosmological impact of astrophysical tests of fundamental physics, including those of the spacetime stability of nature’s fundamental couplings, has only emerged recently. In part this was due to the work done within CAUP’s ‘Dark Side’ project, and these tests are now being included in studies for ESA and ESO’s next-generation of facilities.

While a detection of variations of fundamental couplings will be direct evidence of Equivalence Principle violations and a fifth force in Nature, any such measurements (even null results) can provide tight constraints on additional dynamical degrees of freedom (such as fundamental scalar fields) that are now known to be among Nature’s building blocks.

This thesis will explore the role of these astrophysical tests on cosmology and fundamental physics, with some emphasis on dynamical dark energy. Starting with the experience gained from a recent UVES Large Program, the work will concentrate on the ESPRESSO fundamental physics tests, contributing both to the GTO preparation and its subsequent exploitation. The ESPRESSO experience will also lead to more detailed and realistic feasibility studies for ELT-HIRES.

**University:** Porto

**Starting date:** 2015/10/01

**2015/B007 Fellow: Angela Ng **(*cancelled in 2016*)

**Fellowship: **PD/00040/2012 – PD/BD/113746/2015 - FCT

**Advisors: Francisco S. N. Lobo** (IA-U.Lisboa), **Nelson J. Nunes** (IA-U.Lisboa)

**PhD Topic (2015/411): Astrophysical and cosmological applications of modified theories of gravity**

The late-time cosmic accelerated expansion is one of the most important and challenging current problems in cosmology. Although models of dark energy are the most popular candidates responsible for the cosmic expansion, the latter may be due to modifications of General Relativity, which introduce new degrees of freedom to the gravitational sector itself. This research project will explore the viability of a plethora of modified gravity models, consistently analysing the reproduction of all the cosmological epochs. More specifically, we will consider generalizations of the Einstein-Hilbert action by including non-linear curvature invariants and Lagrangians that also include curvature couplings to the matter sector. Another class of theories under our scrutiny will be generalised scalar-tensor or vector-tensor gravity theories, where scalar or vector fields play gravitational roles that can also be perceived as couplings to matter in an appropriate frame. One fundamental goal of this project is to study the theoretical issues of the extra degrees of freedom of the theory and to analyse its astrophysical applications.

**University:** Lisboa

**Starting date:** 2015/11/01

**2014/B002 Fellow: Ivan Rybak **(*ongoing*)

**Fellowship: **PD/00040/2012 – SFRH/BD/52699/2014 – FCT

**Advisors: Carlos Martins** (IA-U.Porto),** Anastasios Avgoustidis** (University of Nottingham)

**PhD Topic (2014/404): ****Cosmic Paleontology: Searching for Superstrings**

Cosmic strings arise naturally in many proposed theories of new physics beyond the standard model unifying the electroweak and strong interactions, as well as in many superstring inspired inflation models. In the latter case, fundamental superstrings produced in the very early universe may have stretched to macroscopic scales, in which case they are known as cosmic superstrings. If observed, these objects thus provide a unique window into the early universe and possibly string theory. The goal of this thesis will be to study the evolution and astrophysical consequences of these objects, in the context of ongoing and forthcoming observational searches.

**University:** Porto

**Starting date:** 2014/10/01