Parameter estimation with non stationary noise in gravitational waves data

Abstract

The sensitivity of gravitational-waves detectors is characterized by their noise curves which determine the detector's reach and the ability to accurately measure the parameters of astrophysical sources. The detector noise is typically modelled as stationary and Gaussian for many practical purposes. However, physical changes in the state of detectors due to environmental and instrumental factors, including extreme cases where a detector discontinues observing for some time, introduce non-stationarity into the noise. Even slow evolution of the detector sensitivity will affect long duration signals such as binary neutron star (BNS) mergers. Mis-estimation of the noise behavior directly impacts the posterior width of the signal parameters. This becomes an issue for studies which depend on accurate localization volumes such as i) probing cosmological parameters (such as Hubble constant, clustering bias) using cross-correlation methods with galaxies, ii) doing electromagnetic follow-up using localization information from parameter estimation done from pre-merger data. We study the effects of dynamical noise on the parameter estimation of the GW events. We develop a new method to correct dynamical noise by estimating a locally-valid pseudo PSD which is normalized along the time-frequency track of a potential signal. We do simulations by injecting the BNS signal in various scenarios where the detector goes through a period of non-stationarity with reference noise curve of third generation detectors (Cosmic explorer, Einstein telescope). As an example, for a source where mis-modelling of the noise biases the signal-to-noise estimate by even 10%, one would expect the estimated localization volume to be either under or over reported by ∼ 30%; errors like this, especially in low-latency, could potentially cause follow-up campaigns to miss the true source location.

The Dark Side of Using Dark Sirens to Constrain the Hubble–Lemaître Constant

“…Several recent studies have predicted that the third generation of ground-based GW detectors can constrain the Hubble-Lemaître constant to an precision as high as ΔH 0 /H 0  10 −4 using dark sirens (Yu et al 2020;Song et al 2022). However, the sky localizations of a few to a dozen percent of the dark sirens may be biased by nearby SMBHs (e.g., Peng & Chen 2021), strong gravitational lensing (Broadhurst et al 2018;Smith et al 2018;Yang et al 2021;Broadhurst et al 2022), or nonstationary detector noise (Edy et al 2021;Kumar et al 2022). Without properly modeling these effects, the constraint on the Hubble-Lemaître constant is likely to be much weaker.…”

“…Gravitational redshift Chen 2021), or acceleration of the source around a massive body (Robson et al 2018;Tamanini et al 2020;Chen 2021), as well as the gas surrounding the source (Chen & Shen 2019;Caputo et al 2020;Chen et al 2020), could bias the measurement of the mass of the source and in turn induce an error in the inference of the luminosity distance. In addition, the eccentricity of the orbit of a binary (Gayathri et al 2021(Gayathri et al , 2022 and the nonstationary noise of detectors (Edy et al 2021;Kumar et al 2022), if not appropriately accounted for, could also result in biased localization of the source.…”

Cosmography with next-generation gravitational wave detectors

“…Over the last few years, the systematic uncertainties associated with bright sirens have been widely studied, such as the systematics due to the GW instrumental calibration uncertainties [74][75][76], the EM observation selection effect [77][78][79], the biased EM-inferred binary viewing angle [77], the peculiar velocity of the hosts [80][81][82], and the GW instrumental nonstationary noise [83][84][85][86][87]. A comprehensive study of the systematics and the developments of the mitigation methods are critical to ensure the value of standard siren measurements in cosmology, especially when dealing with the large and precise catalog of bright sirens that XG detectors will provide.…”

Subtracting glitches from gravitational-wave detector data during the third LIGO-Virgo observing run

“…When not accounted for as a part of the analyses, the presence of glitches can bias estimates of gravitational-wave properties [14][15][16][17]. There are some techniques proposed in which these assumptions have been relaxed [18][19][20][21], but these methods have not yet been used in an analysis by the LIGO-Virgo-KAGRA (LVK) collaboration.…”