We congratulate Dr José Vargas Lopes who successfully defended his thesis today
José Lopes obtained his MSc in Engineering Physics at Instituto Superior Técnico. He joined the COSTAR group at CENTRA as a master's student, and then he continued pursuing his PhD studies. Dr Lopes's thesis entitled “Stars as Dark Matter cosmic laboratories: from the main- sequence to the horizontal branch” was supervised by Prof. Ilidio Lopes from CENTRA - Center for Astrophysics and Gravitation and co-supervised by Prof. Joseph Silk from University of Oxford, Department of Physics. Parabéns, José!
Abstract:
Dark Matter is a cornerstone of our understanding of the Universe. If the ΛCDM model is to be upheld, galaxies are required to be embedded in a halo of massive non-baryonic matter whose interactions, either with ordinary matter or via self-interactions, have so far eluded our experimental efforts. If these particles do interact with ordinary matter, they will scatter and accumulate in the interiors of stars, where further inter-actions within the stellar plasma can have an effect on the structure and evolution of the star. The importance of the study of these effects is twofold: on one hand, they can improve our understanding of stellar physics; on the other, they can be tested against high precision observations to constrain the properties of DM. In this Thesis, we study the phenomenology of particle DM interactions in a wide variety of stars focusing on the WIMP (Weakly interacting massive particle) DM paradigm. We take advantage of the diversity of the physical processes that characterize different phases of stellar evolution and explore new ways of using astronomical observations to probe and/or constrain the nature of DM. To do this, we have developed a module which models all DM-related processes during the evolution of a given star. This module works in tandem with a widely used open-source stellar evolution code, and together they form a unique laboratory which allows us to test the hypothesis proposed in this Thesis. Using these tools, we have studied three different astrophysical scenarios, each corresponding to a different stage in stellar evolution: the impact of energy transport by asymmetric DM on the structure and evolution of low-mass main-sequence stars; the effects of energy production from DM annihilation in the cores of red giant branch stars; and the impact of DM interactions on the asteroseismology of Red Clump stars. We also carry out a detailed study of the galactic DM phase-space uncertainties that plague the results obtained in the applications described above. Overall, we find that while the search methods proposed in the this work face experimental challenges which hinder their ability to compete with DM-dedicated experiments, near-future developments in astronomy and numerical astrophysics should unlock the unique potential of stars as DM testing grounds. Finally, we note that the versatility of the numerical tools developed during this Thesis allows further development and application to astrophysical scenarios beyond those studied here.