Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Superradiance in the sky   We discuss the conditions under which plane electromagnetic and gravitational
waves can be amplified by a rotating black hole due to superradiant scattering.
We show, in particular, that amplification can occur for low-frequency waves
with an incidence angle parametrically close to 0 (or $\pi$) with respect to
the black hole spin axis and with a parametrically small left (or right)
polarization. This is the case of the radiation emitted by a spinning
electric/magnetic dipole or gravitational quadrupole orbiting a black hole
companion at large radius and co-rotating with the latter. This can yield
observable effects of superradiance, for example, in neutron star-stellar mass
black hole binaries, as well as in triple systems composed by a compact binary
orbiting a central supermassive black hole. Due to superradiance, the total
source luminosity in these systems exhibits a characteristic orbital modulation
that may lead to significant observational signatures, thus paving the way for
testing, in the near future, one of the most peculiar predictions of general
relativity.

21
The categories of this paper are: adap-org
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
29
The categories of this paper are: funct-an
16
The categories of this paper are: stat
20
The categories of this paper are: acc-phys
36
The categories of this paper are: cmp-lg
22
The categories of this paper are: chao-dyn
11
The categories of this paper are: hep-lat
19
The categories of this paper are: eess
17
The categories of this paper are: q-fin
24
The categories of this paper are: dg-ga
27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th