Exploring realistic nanohertz gravitational-wave backgrounds

Understand

Hundreds of millions of supermassive black hole binaries are expected to contribute to the gravitational-wave signal in the nanohertz frequency band.

• Their signal is often approximated either as an isotropic Gaussian stochastic background with a power-law spectrum, or as an individual source corresponding to the brightest binary.
• In reality, the signal is best described as a combination of a stochastic background and a few of the brightest binaries modeled individually.
• We present a method that uses this approach to efficiently create realistic pulsar timing array datasets using synthetic catalogs of binaries based on the Illustris cosmological hydrodynamic simulation.