  A topological superconductor nanowire bears a Majorana bound state at each of
its ends, leading to unique transport properties. As a way to probe these, we
study the finite frequency noise of a biased junction between a normal metal
and a topological superconductor nanowire. We use the non-equilibrium Keldysh
formalism to compute the finite frequency emission and absorption noise to all
order in the tunneling amplitude, for bias voltages below and above the
superconducting gap. We observe noticeable structures in the absorption and
emission noise, which we can relate to simple transport processes. The presence
of the Majorana bound state is directly related to a characteristic behavior of
the noise spectrum at low frequency. We further compute the noise measurable
with a realistic setup, based on the inductive coupling to a resonant LC
circuit, and discuss the impact of the detector temperature. We have also
computed the emission noise for a non-topological system with a resonant level,
exhibiting a zero-energy Andreev bound state, in order to show the
specificities of the topological case. Our results offer an original tool for
the further characterization of the presence of Majorana bound states in
condensed matter systems.
