TESTING GENERAL RELATIVITY IN THE STRONG GRAVITY REGIME
Lead Research Organisation:
University of Nottingham
Department Name: Sch of Mathematical Sciences
Abstract
The recent direct detection of gravitational waves by LIGO marks the beginning of a new era in gravity. Confronting the predictions of general relativity and of alternative theories with gravitational wave observations is a new frontier. The first in this direction is to understand the structure and the dynamics of black holes and compact stars in alternative theories of gravity, as these are the primary source of gravitational waves. This is the main goal on this project. More specific objective include the study of quiescent black holes and compact stars, modelling of gravitational collapse and black hole formation, and the study of the dynamical evolution of binary systems.
Organisations
People |
ORCID iD |
| Thomas Sotiriou (Primary Supervisor) | |
| Giulia Ventagli (Student) |
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/R513283/1 | 01/10/2018 | 30/09/2023 | |||
| 2102878 | Studentship | EP/R513283/1 | 01/10/2018 | 31/03/2022 | Giulia Ventagli |
| Description | The main results of the first 2 years and a half of my PhD have been presented in two different papers, published by Phys. Rev. D. My work is focused on the study of spontaneous scalarization in scalar-tensor theories. Scalar-tensor theories describes gravity both by a tensor and a scalar field. Spontaneous scalarization consists in a mechanism that triggers an instability for the scalar field, which exponentially grows. This can be a viable tool to investigate the presence of modifications to General Relativity in compact objects, such as black holes or neutron stars, since it allows for new interesting physics in the vicinity of compact objects, i.e. in the strong gravity regime, whereas it is indistinguishable from General Relativity at long distances, where gravity is weak. As main findings of the first paper, we identified the most generic theory that exhibit the phenomenon of scalarization by analysing their field equations and identifying those that show the appropriate instability behaviour. Such generic theory has been investigated further in the second paper, where the analysis of the threshold of the instability has been presented. In order to develop the study of the field equations of the theory, I implemented a code with the software Mathematica which allows to mathematically model very compact stars in these theories. I am currently improving the code for allowing a more complete analysis of the theory that will be presented in a forthcoming publication. |
| Exploitation Route | As a result of my work, it is now clear what is the most generic theory that is affected by spontaneous scalarization. This narrows the possibility for chosing which terms to include in a theory such that it triggers this phenomenon. This outcome can be used by other research groups that work on modified gravity. They can build a specific theory which present a phenomenology affected by spontaneous scalarization that is characterized by different properties with respect to General Relativity. Thus, they can put constraints on such theory by requiring that it is in agreement with observations. For example, one could study the gravitational waves produced in such models and provide templates that describes them. This can in turn be used to analyse gravitational waves signal detected by the LIGO and Virgo Scientific Collaborations. The detection of novel properties would give credibility to alternative theories or, more likely, the lack of such detections would help tighten the constraints on modified theories of gravity. |
| Sectors | Other |
| URL | https://linkmix.co/3021225 |