On the Possible Detection of Low Frequency Periodic Signals in Gravitational Wave Interferometers

TL;DR

This paper proposes a method to detect low-frequency gravitational wave signals by injecting a sideband into interferometers, which can be less noisy and sensitive to signals below seismic noise limits.

Contribution

It introduces a novel technique of using an injected sideband at the free spectral range to enhance detection of low-frequency gravitational waves.

Findings

Injected sideband sensitivity matches that of the carrier.

Fsr sideband signals are less affected by noise.

Potential to detect signals below seismic noise threshold.

Abstract

We carried out a computer simulation of a large gravitational wave (GW) interferometer using the specifications of the LIGO instruments. We find that if in addition to the carrier, a single sideband offset from the carrier by the fsr frequency (the free spectral range of the arm cavities) is injected, it is equally sensitive to GW signals as is the carrier. The amplitude of the fsr sideband signal in the DC region is generally much less subject to noise than the carrier, and this makes possible the detection of periodic signals with frequencies well below the so-called seismic wall.