LISA Gravitational Wave Detector Could Measure Black Hole Accretion Disk Properties Without Electromagnetic Data
A new study shows that the upcoming LISA space-based gravitational wave detector can measure properties of gas disks around supermassive black holes by observing extreme-mass-ratio inspirals (EMRIs)—pairs of objects where one is vastly more massive than the other. The research uses relativistic models to show LISA can estimate disk density and accretion rates to within ~10% accuracy without needing simultaneous light-based observations. This capability could help answer fundamental questions about how supermassive black holes grow and evolve alongside their host galaxies.
Researchers have developed a Bayesian analysis framework showing that LISA, the Laser Interferometer Space Antenna scheduled for launch in the coming years, can constrain properties of accretion disks around supermassive black holes by observing extreme-mass-ratio inspirals—systems where a stellar-mass object spirals into a much more massive black hole. Using relativistic models of binary-disk interactions, the team found that LISA observations can simultaneously estimate disk surface density and accretion rates (or luminosity) without requiring electromagnetic counterparts, contrary to earlier Newtonian-based forecasts. The analysis reveals that simpler linear-signal approximations (Fisher matrix methods) are inadequate for these systems, and that torque amplitudes can be constrained to roughly 10% precision. This capability strengthens LISA's potential to probe accretion physics at sub-microparsec scales in the strong-field gravity regime, complementing traditional electromagnetic astronomy and helping identify host galaxies through cross-correlation with AGN catalogs, ultimately advancing understanding of supermassive black hole formation and evolution.
What's missing
The study does not discuss the timeline for LISA's launch, current status of detector development, or how frequently EMRIs are expected to occur in LISA's observable volume—information that would contextualize the practical feasibility of this science goal.
What different sources said
- arXiv astro-phCenter
Gotta light? Illuminating AGN disks with LISA EMRIs
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