Globally coherent short duration magnetic field transients and their effect on ground based gravitational-wave detectors

TL;DR

This paper reports on the detection of global short-duration magnetic field transients that could impact gravitational-wave detectors, emphasizing the need to account for correlated magnetic noise in future searches.

Contribution

It presents the first observations of globally coherent magnetic transients and assesses their potential impact on gravitational-wave detection.

Findings

At least 2.3 coincident magnetic transients per day across sites.

Some transients exceed 200 pT, potentially affecting detector test masses.

Magnetic transients could induce displacements comparable to gravitational-wave signals.

Abstract

It has been recognized that the magnetic fields from the Schumann resonances could affect the search for a stochastic gravitational-wave background by LIGO and Virgo. Presented here are the observations of short duration magnetic field transients that are coincident in the magnetometers at the LIGO and Virgo sites. Data from low-noise magnetometers in Poland and Colorado, USA, are also used and show short duration magnetic transients of global extent. We measure at least 2.3 coincident (between Poland and Colorado) magnetic transient events per day where one of the pulses exceeds 200 pT. Given the recently measured values of the magnetic coupling to differential arm motion for Advanced LIGO, there would be a few events per day that would appear simultaneously at the gravitational-wave detector sites and could move the test masses of order $10^{-18}$ m. We confirm that in the advanced detector era short duration transient gravitational-wave searches must account for correlated magnetic field noise in the global detector network.