Nona Semana Integrada do Instituto de Física de São Carlos

Charged Boson star in scalar-tensor gravity

Não agendado

20m

Doutorado

Palestrante

Sr. Catalin Toma (IFSC-USP)

Descrição

With the advent of high precision observations of radiation from astrophysical sources it becomes important to understand the difference between different types of ultra-compact objects. The most popular type of ultra-compact objects are black holes, which are predictions of General Relativity, i.e. Einstein's theory of gravitation. However, also other, more exotic possibilities exist, amongst which are so-called boson stars, self-gravitating objects composed out of scalar bosons. These possess – in contrast to black holes – no event horizon and should, in principle, be distinguishable from black holes by future detections of gravitational waves (via the LIGO/VIRGO experiment) or electromagnetic radiation (via e.g. the Event Horizon telescope). In order to make a step forward in the understanding of these signals, we have studied the motion of massive and massless test particles in boson star space-times.(1) The former describe e.g. the motion of low mass objects, while the latter are important both in the understanding of light deflection as well as gravitational wave emission.The focus of this upcoming presentation will be a model of a a charged boson star with an additional non-minimal coupling between a gravity scalar and the field strength tensor of the electromagnetic field, in scalar-tensor gravity.(2-3) A collocation method from the COLSYS program was implemented in order to solve the equations of motion. The dependencies of various parameters will be highlighted, for different types of profiles of the gravity scalar (different node branches). The behavior of the coupling between the gravity scalar and the electromagnetic field strength tensor was of particular interest.

Referências

1 DIEMER, V. ;et al. Geodesic motion in the spacetime of a non-compact boson star. Physical Review D, v. 88, n.4, p.044025,2013
2 BRIHAYE, Y.; DIEMER, V. ; HARTMANN, C. Charged Q-balls and boson stars and dynamics of charged test particles. Physical Review D, v. 89,p. 084048, 2014.doi:10.1103/PhysRevD.89.084048.
3 HERDEIRO,C. A. R. ;RADU, E.; SANCHIS-GUAL,N.;FONT, J. A. Spontaneous scalarisation of charged black holes. Physical Review Letters, v. 121, n.10, p.101102,2018.