Astronomy

A sound wave becomes a cosmic ruler

Follow an expanding acoustic shell around an initial overdensity. Change the sound horizon and inspect the preferred separation left in the galaxy-pair signal.

By Mykhailo Makarov

Actual application image

The model and its limits

A Gaussian shell and correlation-function peak illustrating a standard ruler. The sound horizon is an input; baryon–photon fluid dynamics and survey selection are not computed.

Equations used in the module

Equations
shell(r) ∝ exp[-(r-r_s)²/(2σ²)]; r_s is a supplied comoving standard ruler

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