Black hole phenomenology and dark matter searches
- Autores: Francesca Scarcella
- Directores de la Tesis: Miguel Ángel Sánchez Conde (dir. tes.)
- Lectura: En la Universidad Autónoma de Madrid ( España ) en 2022
- Idioma: español
- Tribunal Calificador de la Tesis: Sésbastien Clesse (presid.), Savvas Nesseris (secret.), Christian Byrne (voc.)
- Programa de doctorado: Programa de Doctorado en Física Teórica por la Universidad Autónoma de Madrid
- Materias:
- Enlaces
- Tesis en acceso abierto en: Biblos-e Archivo
- Resumen
The matter we are made of, and that we have learned to describe through the Standard Model of particle physics, makes up for only about a fifth of the total matter in the Universe.
Unravelling the nature of the remainder, the \emph{dark matter}, is undoubtedly one of the main quests of modern physics.
In this thesis we discuss some possible inter-plays between dark matter searches and the physics of black holes.
In particular, we consider black holes forming in the early Universe, long before the birth of stars and galaxies. These are known as \emph{primordial black holes}, and could originate from the gravitational collapse of large (order one) density perturbations from inflation. If black holes of this kind exist, they would make up a part, possibly even all, of the dark matter. The discovery of such objects would have far reaching consequences for the study of the dark matter, even if they were found to constitute only a subdominant component of it. Primordial black holes with masses ranging between a few and a hundred solar masses have recently been the subject of extensive studies and debate, following the recent detections of merging black hole binary systems through gravitational waves. In this thesis we discuss two complimentary observational channels for the observation of black holes in this mass range.
Firstly, we consider the intense electromagnetic radiation that can be emitted by the process of gas accretion. We study the possibility of detecting isolated black holes in our Galaxy through this channel, separately examining the black hole population of astrophysical origin and an hypothetical primordial one. Multi-wavelength studies are essential for the identification of this type of sources. We consider the X-ray and radio bands, including prospects for radio detection with the future Square Kilometre Array telescope.
Regarding the astrophysical population, our findings suggest that the detection of isolated black holes in the vicinity of the galactic centre is around the corner. We perform a complete parametric study of the uncertainty associated with this prediction.
Turning to primordial black holes, the same observational channel can be used to constrain the abundance of these objects in the Universe. We explore the uncertainties associated with this bound and its dependence on the primordial black hole population model. In particular, we consider a multi-modal mass distribution which arises naturally from the thermal history of the Universe. We find that in this case constraints are significantly weakened.
In the second part of this work we turn to gravitational wave observations. At the time of writing, almost one hundred black hole merger events have been detected. While attempts have been made to disentangle the astrophysical background form a possible primordial signal in present data, any conclusion is hampered by large theoretical uncertainties on the properties of both populations. Third-generation gravitational wave detectors such as the Einstein Telescope will be able to detect mergers up to immense distances, corresponding to epochs preceding the birth of the first stars. At such distances, the astrophysical background is expected to be absent.
We discuss the theoretical redshift dependence of the merger rates of astrophysical and primordial black holes, together with their most relevant uncertainties. Through the process of mock data generation and analysis, we assess the ability of the Einstein Telescope to identify a subdominant population of primordial black holes, disentangling it from the astrophysical one based exclusively on measurements of the distances to the events. In particular, we model and discuss the important role played by the instrumental errors on distance measurements.
We find that the Einstein Telescope should be able to detect and constrain the abundance of primordial black holes if these constitute at least approximately one part in $ 10^{5}$ of the total dark matter.
