Galaxy Dancers: A dynamical study of globular star clusters
Abstract
Globular clusters are roughly spherical collections of hundreds of thousands or millions of stars that orbit a host galaxy. Very old, with typical ages similar to the one of their hosts, these dense clusters hold many interesting aspects that make them a great laboratory to study astrophysics. For instance, their dense environment contributes to increased dynamical interactions between its stars, sometimes giving birth to exotic objects like black holes with masses within the pair-instability gap, cataclysmic variables and pulsars. Their continuous tidal interactions with their host galaxy might also produce long and prominent stellar streams that tell much about the past dynamical history of themselves, and of their host. Other aspects such as different chemical populations and the fact that there is still no consensus on how globular clusters were formed makes the study of these sources challenging and exciting. Given the interesting possibilities that globular clusters offer to learn physics, this thesis was focused in understanding and modelling their internal and external dynamical interactions, using both simulations and state-of-the-art data from the Hubble Space Telescope (HST) and the Gaia astrometric mission. I have analysed aspects such as core-collapse, tidal interactions and mass segregation, how they can be measured from data and how they influence different aspects of stellar and orbital evolution. Among the noteworthy accomplishments of this thesis, it is important to mention (1) the improvements in data modelling concerning density profiles, proper motion measurements and Jeans kinematic modelling; (2) the detection of sub-clusters of stellar remnants in the cores of nearby globular clusters, which might be associated to exquisite events like fast radio bursts, compact object mergers, and gravitational waves; and (3) the presentation of new constraints on globular cluster formation scenarios, especially the one pertaining the presence of a dark matter mini-halo. The results obtained over the course of this work and the methods that I developed will contribute to the overall effort to better understand the internal and external evolution of globular clusters, and to make the best use of large astrometric data sets like Gaia and HST, and in the future, the James Webb Space Telescope and the Nancy Grace Roman Space Telescope.
- Publication:
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Ph.D. Thesis
- Pub Date:
- October 2022
- Bibcode:
- 2022PhDT.........3V