A Gravitational Wave Detector for Post Merger Neutron Stars: Beyond the Quantum Loss Limit of Michelson Fabry Perot Interferometer

TL;DR

This paper introduces a novel gravitational-wave detector design with an L-resonator that surpasses traditional interferometers in high-frequency sensitivity, enabling more effective detection of post-merger neutron star signals.

Contribution

The paper proposes an innovative interferometer configuration with an L-resonator, achieving superior high-frequency sensitivity and higher detection rates for neutron star mergers compared to existing designs.

Findings

Significantly improves high-frequency sensitivity over existing detectors.

Achieves a detection rate of 1 to 30 neutron star merger events per year.

Outperforms other third-generation detectors by a factor of 3 to 7 in SNR.

Abstract

Advanced gravitational-wave detectors that have made groundbreaking discoveries are Michelson interferometers with resonating optical cavities as their arms. As light travels at finite speed, these cavities are optimal for enhancing signals at frequencies below their bandwidth frequency. A small amount of optical loss will, however, significantly impact the high-frequency signals which are not optimally amplified. We find an elegant interferometer configuration with an "L-resonator" as the core, significantly surpassing the loss limited sensitivity of dual recycled Fabry Perot Michelson interferometers at high frequencies. Following this concept, we provide a broadband design of a 25 km detector with outstanding sensitivity between 2-4 kHz. We have performed Monte-Carlo population studies of binary neutron star mergers, given the most recent merger rate from the GWTC-3 catalog and several representative neutron star equations of state. We find that the new interferometer configuration significantly outperforms other third-generation detectors by a factor of 3 to 7 in the signal-to-noise ratio of the post-merger signal. Assuming a detection threshold with signal-to-noise ratio >5 and for the cases we have explored, the new design is the only detector that confidently achieves a detection rate larger than one per year, with the rate being 1 to 30 events per year.