Speaker
Description
The Galactic Centre contains populations of stellar-mass and
substellar-mass compact objects orbiting the central black hole,
classified as early extreme-mass ratio inspirals (E-EMRIs) and extremely
large mass ratio inspirals (XMRIs). These systems constitute asymmetric
binaries, characterized by mass ratios exceeding 10,0000 to 1. This mass
differential causes the secondary body to approximate a test particle,
completing tens of thousands or millions of orbital cycles prior to
coalescence. This high cycle count delineates the spacetime geometry and
multipolar structure of the central black hole with greater resolution
than comparable-mass supermassive black hole binaries, which undergo
rapid coalescence and exhibit fewer in-band cycles. The prolonged
orbital data can in principle also facilitate topological analysis. By
applying the Gauss-Bonnet theorem, the accumulated orbital precession
parameters relate the integrated curvature of the spacetime to its
topological invariants. The continuous gravitational wave emission from
these populations generates a non-Gaussian, non-stationary composite
signal within the frequency band of the Laser Interferometer Space
Antenna. This aggregated signal comprises an incoherent superposition of
individual waveforms from eccentric and circular orbits, which
superimposes upon the spectral signatures of other target sources,
including binaries of supermassive black holes and verification
binaries. Spectral analysis indicates that sources with minimal
frequency drift constitute an unresolved stochastic background, while
systems with measurable frequency evolution produce distinct spectral
components. Extracting targeted signals from this composite data
requires time-frequency domain modeling and non-Poissonian statistical
subtraction protocols.