Exploring the spectrum of stochastic gravitational-wave anisotropies with pulsar timing arrays

Understand

Anisotropies in the nanohertz gravitational-wave background are a compelling next target for pulsar timing arrays (PTAs).

• Measurements or informative upper limits to the anisotropies are expected in the near future and can offer important clues about the origin of the background and the properties of the sources.
• Given that each source is expected (in the simplest scenario of circular inspirals) to emit at a fixed frequency, the anisotropy will most generally vary from one frequency to another.
• The main result presented in this work is an analytical model for the anisotropies produced by a population of inspiralling supermassive black-hole binaries (SMBHBs).