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Free keywords:
Astrophysics, Instrumentation and Methods for Astrophysics, astro-ph.IM,General Relativity and Quantum Cosmology, gr-qc
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 $\sim 30\%$; errors like this, especially in low-latency, could
potentially cause follow-up campaigns to miss the true source location.
