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Quantum noise imposes a fundamental limitation on the sensitivity of interferometric gravitational-wave detectors like LIGO, manifesting as shot noise and quantum radiation pressure noise. Here we present the first realization of frequency-dependent squeezing in full-scale gravitational-wave detectors, resulting in the reduction of both shot noise and quantum radiation pressure noise, with broadband detector enhancement from tens of Hz to several kHz. In the LIGO Hanford detector, squeezing reduced the detector noise amplitude by a factor of 1.6 (4.0 dB) near 1 kHz, while in the Livingston detector, the noise reduction was a factor of 1.9 (5.8dB). These improvements directly impact LIGO’s scientific output for high-frequency sources (e.g., binary neutron star post-merger physics). The improved low-frequency sensitivity, which boosted the detector range by 15–18 % with respect to no squeezing, corresponds to an increase in astrophysical detection rate of up to 65%. Frequency-dependent squeezing was enabled by the addition of a 300-meter long filter cavity to each detector as part of the LIGO A+ upgrade.
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A Study of Gravitational Wave Memory and Its Detectability With LIGO Using Bayesian Inference
The detectable component of gravitational waves, known as the oscillatory waveform, is predicted to have a smaller, lower frequency counterpart called the memory: a permanent warping of space-time. The memory component is low-frequency (below the usual LIGO frequency band starting at 20 Hz), and low amplitude. Low frequency noise sources on earth make it difficult for ground based detectors to reach the SNR (signal to noise ratio) needed to detect this component. We use Bayesian parameter estimation on simulated events with future detector sensitivities, to determine the detector noise spectrum, event masses, and detected SNR required to detect gravitational wave memory.
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- Award ID(s):
- 1757303
- PAR ID:
- 10089816
- Date Published:
- Journal Name:
- LIGO Laboratory Summer 2018 Undergraduate Research
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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