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Resolving fundamental physics and astrophysical problems

Kinwah Wu (MSSL-UCL) // January 24, 2022


Abstract: Extreme-mass-ratio binaries (EMRBs) and intermediate-mass-ratio binaries (IMRBs) with a millisecond pulsar are gravitational-wave sources to be observed by LISA, with a guaranteed electromagnetic counterpart. These systems have complex orbital and spin dynamics, which have observational signatures, caused by spin-orbit and spin-spin coupling (through spin-curvature interaction). The narrow mass range of neutron stars greatly reduces the search space in gravitational wave experiments and radio pulsar timing observations when establishing the system parameters and dynamical variables. This subgroup of EMRBs and IMEBs will help us to resolve important astrophysical problems, e.g. the validity of extending the M(BH)-sigma scaling for galactic spheroids to the very low-mass galaxies, and whether or not low-mass dwarf galaxies and globular clusters harbour nuclear intermediate-mass black hole. The extremely high precision that can be achieved in gravitational wave experiments and radio pulsar timing observations will provide an opportunity to directly detect gravitational clock effects arisen from spin couplings. Radio monitoring of the orbital and spin evolution of the millisecond pulsar in EMRBs can be used for deriving bootstrap methods for the correction the drifts in the phases in the gravitational waves emitted from the EMRBs caused by the self-force, a challenge needed to be resolved before the launch of LISA.

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