Wave dark matter as a gravitational lens for electromagnetic and gravitational waves

QB Astronomy;QC Physics

Herrera Martín, Antonio ; Martin, Hendry A.

University:University of Glasgow

Department:School of Physics and Astronomy

关键词: Cosmology, graviational lensing, gravitational waves, wave dark matter, scalar field dark matter, dark matter.;   

Others  :  http://theses.gla.ac.uk/9027/7/2018HerreraMartinPhD.pdf

来源: University of Glasgow

【 摘 要 】

The majority of the matter in the known universe is believed to be in the form of Dark Matter, and its widely accepted description is done by Cold Dark Matter (CDM). Nevertheless, its exact properties and composition are still unknown, and it is one of the most active areas of research in Cosmology. The use of Cold Dark Matter has been successful to describe the general behaviour of Dark Matter at large scales. However, it has encountered problems explaining phenomena at other regimes as on the scale of galaxy halos. Therefore, other models have been proposed over time which are able to retain the reasonable success of CDM on large scales and extent it to other regimes where CDM has problems to explain the observed data. One of such models is Scalar field Dark Matter (SFDM). Its properties allow it to produce similar results at large scales and solve the problems encountered at galactic scales. Nevertheless, the difficulty to obtain direct observations of Dark Matter makes it difficult to give a definitive comparison between the models. Therefore, it is important to study dark matter through different methods of analysis that would allow to increase the validity of its scope, and these methods are constantly being researched. In this work, a particular density profile known as Wave Dark Matter is implemented as a gravitational lens to study its behaviour in the cases where it produces strong lensing of light and of gravitational waves. Analytical functions for the description of a soliton core and a soliton core + NFW tail are applied to a sub-sample of 6 galaxies from The Sloan Lens ACS Survey to constrain the lensing parameters and their relation with the profile. Furthermore, by considering the soliton core to be the main contributor to the mass profile, this is implemented as a lens for the case of the wave approximation and further to describe the major effects of the lens on gravitational waves. It was found that the soliton core is too compact and dense in order to reproduce the observed values of the data for the lensed galaxies. However, adding a NFW tail alleviates the problem and reaches radii and masses within the range reported in the literature, although the size of the NFW tail cannot be properly constrained. Meanwhile for gravitational waves, it was found that the lensing parameters of the soliton core, if they are expected to describe a galaxy, will be such that they are more likely to be observed spaceborne gravitational wave detectors. In summary, therefore, a wave dark matter soliton in combination with a NFW tail is able to represent a galaxy, and the combination of ligh and gravitational waves should give new insight on the validity of the profile as a description of Dark Matter galactic haloes.