: These are global electromagnetic resonances excited by lightning strikes in the cavity between the Earth's surface and the ionosphere. They create magnetic fields that are coherent over thousands of kilometers, potentially causing correlated noise between distant detector sites.
: Magnetic fluctuations can induce noise in the sensitive cabling and control electronics used to read out the detector's data. 3. Impact on Scientific Discovery
Intense or correlated magnetic noise directly limits the "reach" of GW astronomy:
In gravitational wave (GW) detectors, intense or fluctuating magnetic fields create "magnetic noise" that can mimic or obscure the incredibly faint signals from cosmic events like black hole mergers. This noise is a critical challenge for current interferometers like LIGO and Virgo , and it is expected to be a primary limiting factor for next-generation detectors like the Einstein Telescope . 1. Primary Sources of Magnetic Noise