LISA and Capture Sources

Abstract

LISA is a joint ESA/NASA mission to detect and observe gravitational waves. It is designed to register the change in distance between free-falling reference points to picometer accuracy, allowing to measure the effect of gravitational waves created by the coalescence of massive black holes almost anywhere in the universe, stellar mass black holes and neutron stars spiraling into massive black holes in other galaxies at intermediate distances, and tightly orbiting binary stars in our galaxy. LISA will be able to detect gravitational waves from coalescing massive black holes to redshifts of z ∼ 10 and higher, allowing an unprecedented view into the early stages of galaxy formation. The signals from the many million binary stars in our galaxy yield information about the evolution and the morphology of our galaxy, giving a view of the population of binary stars unobstructed by dust. Among the most challenging, yet scientifically interesting sources are the captures of a small massive object by massive black holes where the mass ratio exceeds 1,000. Those events, named extreme mass ratio inspirals (EMRI), create very complex waveforms and allow to test general relativity to very high precision. LISA has been recently confirmed as a candidate for the L1 mission in ESA’s Cosmic Vision program and is foreseen to be launched in the 2018 time frame.