arXiv subjects

Shun Yin Cheung

Publications and source records attributed to Shun Yin Cheung.

5 recordsLinked to original sources

arXiv2026

Joint inference for gravitational-wave signal and noise glitch: Method and application

Non-Gaussian noise transients ("glitches") in gravitational-wave observatories degrade our ability to accurately perform astrophysical inference. We present the analysis pipeline bilby_glitch, which allows for simultaneous Bayesian inference of gravitational-wave signals and glitches. Our framework is modular and built on top of the popular bilby framework, facilitating future extensions with additional glitch and signal models. We integrate transdimensional bilby into our framework and discuss three glitch models: a physically-motivated slow scattering model, and flexible sine-Gaussian and chirplet models. Using a combination of simulated and real data, we demonstrate that bilby_glitch produces reliable results. We then reanalyse two gravitational-wave events - GW191109 and GW200129 - which show signs of interesting black-hole spins, but which may also be affected by data-quality issues. Our results for GW191109 are consistent with previous analysis. For GW200129, we recover results consistent with Payne et al., where the evidence of spin-precession is much weaker when using the waveform approximant NRSur7dq4 in combination with wavelet-based glitch modeling. Furthermore, we show the astrophysical conclusion of this event is dependent on the interplay between the waveform approximant and glitch model, since in contrast to NRSur7dq4 we find that inference with the waveform approximant IMRPhenomXPHM shows strong evidence of spin-precession when used in combination with wavelet-based glitch modeling.

gr-qc↗

arXiv2026

A Gaussian process framework for testing general relativity with gravitational waves

Gravitational-wave astronomy provides a promising avenue for the discovery of new physics beyond general relativity as it probes extreme curvature and ultra-relativistic dynamics. However, in the absence of a compelling alternative to general relativity, it is difficult to carry out an analysis that allows for a wide range of deviations. To that end, we introduce a Gaussian process framework to search for deviations from general relativity in gravitational-wave signals from binary black hole mergers with minimal assumptions. We employ a kernel that enforces our prior beliefs that - if gravitational waveforms deviate from the predictions of general relativity - the deviation is likely to be localised in time near the merger with some characteristic frequency. We demonstrate this formalism with simulated data and apply it to events from Gravitational-Wave Transient Catalog 3. We find no evidence for a deviation from general relativity. We limit the fractional deviation in gravitational-wave strain to as low as 7% (90% credibility) of the strain of GW190701_203306.

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arXiv2025

A search for extra polarisations using a Gaussian process in Gravitational-Wave Transient Catalogue 3

General relativity predicts that gravitational waves are described by two polarisation states: the plus $+$ state and cross $\times$ state. However, alternate theories of gravity allow up to six polarisations. We employ the gravitational-wave null stream, a linear combination of three or more detectors where the $+$ and $\times$ signals add to zero, leaving behind noise and potentially gravitational waves in non-standard polarisation states. We develop a Gaussian process model to search for extra polarisations beyond general relativity. Using data from 42 three-detector events from LIGO-Virgo-KAGRA's Third Gravitational-Wave Transient Catalogue, we find no evidence of non-standard polarisations. We set upper limits on the fractional deviation in gravitational-wave strain to be as low as 0.39 at 90% credibility for the event GW190602_175927.

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arXiv2025

Possible Causes of False General Relativity Violations in Gravitational Wave Observations

General relativity (GR) has proven to be a highly successful theory of gravity since its inception. The theory has thrivingly passed numerous experimental tests, predominantly in weak gravity, low relative speeds, and linear regimes, but also in the strong-field and very low-speed regimes with binary pulsars. Observable gravitational waves (GWs) originate from regions of spacetime where gravity is extremely strong, making them a unique tool for testing GR, in previously inaccessible regions of large curvature, relativistic speeds, and strong gravity. Since their first detection, GWs have been extensively used to test GR, but no deviations have been found so far. Given GR's tremendous success in explaining current astronomical observations and laboratory experiments, accepting any deviation from it requires a very high level of statistical confidence and consistency of the deviation across GW sources. In this paper, we compile a comprehensive list of potential causes that can lead to a false identification of a GR violation in standard tests of GR on data from current and future ground-based GW detectors. These causes include detector noise, signal overlaps, gaps in the data, detector calibration, source model inaccuracy, missing physics in the source and in the underlying environment model, source misidentification, and mismodeling of the astrophysical population. We also provide a rough estimate of when each of these causes will become important for tests of GR for different detector sensitivities. We argue that each of these causes should be thoroughly investigated, quantified, and ruled out before claiming a GR violation in GW observations.

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arXiv2024

Does spacetime have memories? Searching for gravitational-wave memory in the third LIGO-Virgo-KAGRA gravitational-wave transient catalogue

Gravitational-wave memory is a non-linear effect predicted by general relativity that remains undetected. We apply a Bayesian analysis framework to search for gravitational-wave memory using binary black hole mergers in LIGO-Virgo-KAGRA's third gravitational-wave transient catalogue. We obtain a Bayes factor of $\ln \text{BF}=0.01$, in favour of the no-memory hypothesis, which implies that we are unable to measure memory with currently available data. This is consistent with previous work, suggesting that a catalogue of $\mathcal{O}(2000)$ binary black hole mergers is needed to detect memory. We look for new physics by allowing the memory amplitude to deviate from the prediction of general relativity by a multiplicative factor $A$. We obtain an upper limit of $A<23$ ($95\%$ credibility).

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