Abstract
Bosonic fields can give rise to self-gravitating structures. These are interesting hypothetical new “dark matter stars” and good descriptions of dark matter haloes if the fields are very light. We study the dynamical response of Newtonian boson stars (NBS) when excited by external matter (stars, planets or black holes) in their vicinities. Our setup can describe the interaction between a massive black hole and the surrounding environment, shortly after the massive body has undergone a “kick”, due to the collapse of baryonic matter at the galactic center, or dark matter depletion as a reaction to an inspiralling binary. We perform the first self-consistent calculation of dynamical friction acting on moving bodies in these backgrounds. Binaries close to coalescence “stir” the NBS core, and backreaction affects gravitational waveforms at leading −6PN order with respect to the dominant quadrupolar term; the coefficient is too small to allow detection by next-generation interferometers. We also show that the gravitational collapse to a supermassive black hole at the center of a NBS is accompanied by only a small change in the surrounding core. The NBS eventually gets accreted, but for astrophysical parameters this occurs only after several Hubble times.
Highlights
The nature and properties of dark matter (DM) are arguably among the most important open issues in science
It has been recently recognized that ultralight boson fields with masses of the order of 10−22 eV are a compelling candidate for cold DM [9,10,11,12,13]
We find an insignificant change in the local DM mass density, δρM (0)/ρM (0) ∼ 10 mp/MNBS
Summary
The nature and properties of dark matter (DM) are arguably among the most important open issues in science. We have in mind the understanding of local changes in the density triggered by the presence of a massive BH or star, the drag exerted by the bosonic clump on stars moving within it, the flux of energy and momentum induced by coalescing binaries, etc These issues are relevant for large scale DM structures and GW physics [21, 24,25,26,27], and from the perspective of the interaction between DM stars and neutron stars or black holes (BHs) [28]. The Newtonian, non-relativistic approximation requires the source to have a small frequency 10−7 μ/10−22eV Hz. Treating perturbers as pointlike is a successful and standard tool in BH perturbation theory [43,44,45], in seismology [46] or in calculations of gravitational drag by fluids [47, 48]. The energy lost by the crossing particle, Elost, is shown and is only a fraction of Erad, since the scalars have nonzero rest-mass
Sign-in/Register to view highlights & summary 
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call