Author: Ningyuan Lillian GuoPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Ultralight dark matter (ULDM) is an interesting alternative to the standard cold dark matter scenario that admits new physics on kiloparsec scales. In this scenario, dark matter particles have a mass m ~ O(1022 eV), and their dynamics is governed in the non-relativistic weak- eld limit by the Schr odinger-Poisson equation. Coherent "solitons" are predicted to form at the centre of dark matter halos. This thesis presents eigenvalue solutions to the Schr odinger-Poisson equation for purely self-gravitating ULDM, as well as ground state solutions (solitons) for the Schr odinger-Poisson equation with added external central potential, and with attractive ULDM self-interaction. Relationship between soliton density and black hole mass as well as soliton mass is explored. A new pseudospectral solver is then presented for the Schr odinger-Poisson equation under spherical symmetry. It is used to model a central black hole absorbing mass from the soliton by adding a localised imaginary potential, which can be tuned to the absorption model. This allows the rst qualitative dynamical simulations of solitons governed by the Schr odinger- Poisson equation loosing mass to a black hole. Due to a lack of a well-established theory for black hole absorption of ULDM, an empirical model is investigated, showing that it can lead to a range of dynamical behaviours. ULDM central density can change substantially as the black hole mass evolves, and the overall soliton lifetime may be a function of the dynamically changing pro le. A moderate absorption rate is found to be most e cient in removing mass from the soliton. With astrophysically relevant parameters, this code can serve as a valuable tool to understanding whether galactic-centre solitons are expected to have an observable contribution to the mass around supermassive black holes. The code can also be used to model dynamics of axion stars forming from heavier ULDM particles, and mass loss of solitons through e.g. axion-radiation conversion.