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Pulsar Timing Array: Hellings–Downs Correlation

Interactive 3D pulsar timing array: a stochastic gravitational-wave background induces correlated timing residuals across a sky array of millisecond pulsars, and the measured pair correlation vs. angular separation builds up toward the Hellings–Downs curve — the smoking-gun signature used by NANOGrav.

Space & Astronomy3DAdvanced60 FPS📱 Mobile-adapted⇄ 2D version

This simulator places a sky array of millisecond pulsars around Earth and drives their timing residuals with a real Hellings–Downs covariance model: every epoch, a correlated gravitational-wave-background component (built from the exact Γ(θ) angular-correlation formula via Cholesky factorisation) is added to each pulsar alongside independent timing noise. A live scatter plot accumulates the measured pair-wise correlation against angular separation using an online Pearson estimator, letting you watch the classic Hellings–Downs curve — the accepted signature of a gravitational-wave background used by NANOGrav and other pulsar timing consortia — emerge from noise as observation time, array size and signal strength increase.

⚙ Under the hood

Watch correlated timing residuals from a stochastic gravitational-wave background build up across a sky array of pulsars into the Hellings–Downs curve, the real signature used by NANOGrav to report evidence for a nanohertz gravitational-wave background.

pulsar timing arraygravitational wavesHellings-DownsastrophysicsNANOGravcorrelation

3D · Three.js / WebGL renderer · 60 FPS target · runs fully client-side, no install