  The accretion of dark matter (DM) into astrophysical black holes slowly
increases their mass. The rate of this mass accretion depends on the DM model
and the model parameters. If this mass accretion effect can be measured
accurately enough, it is possible to rule out some DM models, and, with the
sufficient technology and the help of other DM constraints, possibly confirm
one model. We propose a DM probe based on accreting pulsar-black hole binaries,
which provide a high-precision measurement on binary orbital phase shifts
induced by DM accretion into black holes, and can help rule out DM models and
study the nature of DM.
