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Free keywords:
Astrophysics, High Energy Astrophysical Phenomena, astro-ph.HE, Astrophysics, Instrumentation and Methods for Astrophysics, astro-ph.IM,General Relativity and Quantum Cosmology, gr-qc
Abstract:
We demonstrate that gravitational waves from binary systems can provide
smoking gun evidence for ultralight bosons (such as ultralight axions). If
ultralight bosons exist, they will form "clouds" by extracting rotational
energy from astrophysical black holes of size comparable to the boson Compton
wavelength through superradiant instabilities. The properties of the cloud are
intimately related with those of the black hole, and they are encoded in the
gravitational waves emitted by compact objects orbiting the black hole/cloud
system. We show that a single measurement of these waves yields at least three
independent ways to estimate the mass of the boson from the cloud.
Gravitational wave observations by the Laser Interferometric Space Antenna
(LISA) could either confirm the existence of ultralight bosons and measure
their mass via "consistency tests" similar to the general relativity tests
routinely performed with binary pulsars, or rule out the cloud's existence.
