  Scalar fields can give rise to confined structures, such as boson stars or
Q-balls. These objects are interesting hypothetical new "dark matter stars,"
but also good descriptions of dark matter haloes when the fields are
ultralight. Here, we study the dynamical response of such confined bosonic
structures when excited by external matter (stars, planets or black holes) in
their vicinities. Such perturbers can either be plunging through the bosonic
configuration or simply act as periodic sources. Our setup can also efficiently
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. It also depicts dark matter
depletion as a reaction to an inspiralling binary within the halo. We calculate
total energy loss, and linear and angular momenta radiated during these
processes, and perform the first self-consistent calculation of dynamical
friction acting on moving bodies in these backgrounds. We show that the
gravitational collapse to a supermassive black hole at the center of a
Newtonian boson star (NBS) is accompanied by a small change in the surrounding
core. The NBS eventually gets accreted, but only on times larger than a Hubble
scale for astrophysical parameters. Stellar or supermassive binaries are able
to "stir" and expel scalar from the NBS. For binaries in the LIGO or LISA band,
close to coalescence, scalar emission affects the waveform at leading $-6$ PN
order with respect to the dominant quadrupolar term; the coefficient is too
small to allow detection by next-generation interferometers. Our results
provide a complete picture of the interaction between black holes or stars and
the ultralight dark matter environment they live in.
