Tidal effects in the motion of gas clouds around boson stars

Abstract

We study the motion of gas clouds in the vicinity of boson stars, performing simulations with the black hole accretion code. We compare the motion of the gas clouds with particle motion along geodesics and analyze the tidal effects on the gas clouds, which leads to the disruption of the clouds. First we consider small and dense clouds associated with three different types of bound orbits close to the boson star and analyze the mechanisms of debris formation for these. We infer from the simulations that the lifetimes of these nearby clouds are longer for initially circularly orbiting clouds than for clouds on initially eccentric orbits. Next we compare the evolution of more extended and less dense clouds on initially circular orbits around a boson star and a Schwarzschild black hole and compare the motion in these two spacetimes. In particular, we observe the formation of a ringlike structure around the boson star endowed with a spiralling shock structure and a constant thermal bremsstrahlung total luminosity. This final configuration contrasts strongly with the black hole scenario where the gas is totally captured behind the event horizon.