No Pulsar Timing Noise from Brownian Motion of the Sun

TL;DR

This paper argues that the Sun's Brownian motion caused by asteroids cannot mimic the gravitational wave signals detected by pulsar timing arrays, due to the distinct dipole signature it would produce.

Contribution

The paper demonstrates that asteroid-induced Sun motion would create a detectable dipole pattern, distinguishing it from true gravitational wave signals in pulsar timing data.

Findings

Asteroid perturbations produce a large dipole in pulsar timing signals.

Such a dipole would be detectable by PTA collaborations.

No evidence of this dipole has been observed, ruling out the asteroid hypothesis.

Abstract

It was recently claimed (arXiv:2405.05410 [gr-qc]) that evidence for a stochastic gravitational wave background observed by pulsar timing arrays can be attributed instead to random perturbations of the Sun's motion by transiting asteroids. I show that that this would lead to a large dipole component accompanying a much smaller quadrupolar perturbation of pulsar timing signals, which would not be confused with a gravitational wave signal. Such an anomalous dipole would have been detected and identified as a spurious background by the PTA collaborations, if it existed.