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Astrophysics, astro-ph,General Relativity and Quantum Cosmology, gr-qc
Abstract:
We consider a model in which massive stars form in a self-gravitating
accretion disk around an active galactic nucleus (AGN). These stars may evolve
and collapse to form compact objects on a time scale shorter than the accretion
time, thus producing an important family of sources for LISA. Assuming the
compact object formation/inspiral rate is proportional to the steady-state gas
accretion rate, we use the intrinsic hard X-ray AGN luminosity function to
estimate expected event rates and signal strengths. We find that these sources
will produce a continuous low-frequency (<~ mHz) background detectable by LISA
if more than 1% of the accreted matter is in the form of compact objects. For
compact objects with masses >~ 10 solar masses the last stages of the inspiral
events should be resolvable above a few mHz, with rates as high as a few
hundred per year.
