The Hunt for Environmental Noise in Virgo during the Third Observing Run

Abstract

The first twenty years of operation of gravitational-wave interferometers have shown that these detectors are affected by physical disturbances from the surrounding environment. These are seismic, acoustic, or electromagnetic disturbances that are mainly produced by the experiment infrastructure itself. Ambient noise can limit the interferometer sensitivity or potentially generate transients of non-astrophysical origin. Between 1 April 2019 and 27 March 2020, the network of second generation interferometers—LIGO, Virgo and GEO—performed the third joined observing run, named O3, searching for gravitational signals from the deep universe. A thorough investigation has been done on each detector before and during data taking in order to optimize its sensitivity and duty cycle. In this paper, we first revisit typical sources of environmental noise and their coupling paths, and we then describe investigation methods and tools. Finally, we illustrate applications of these methods in the hunt for environmental noise at the Virgo interferometer during the O3 run and its preparation phase. In particular, we highlight investigation techniques that might be useful for the next observing runs and the future generation of terrestrial interferometers.

Impact of Schumann resonances on the Einstein Telescope and projections for the magnetic coupling function

“…When analysing data in a search for an isotropic GWB using interferometers I and J, one typically constructs the magnetic cross-correlation statistic Ĉmag,IJ (f ) to investigate if the observed magnetic fields might result in correlated noise in the analysis [16,28]. The magnetic coupling functions κ I,J (f ) are measured by injecting magnetic fields with known amplitude and frequency and observing their impact on the output in the GW data s I,J (t) [6,7].…”

“…One should study local magnetic noise carefully as this could be a correlated noise source as well because each local corner station for the triangular ET set-up will likely house mirrors for two of the three interferometers (separated by ∼ 300 m and in different vacuum tubes). To model local magnetic fields of a GW interferometer, we consider the local magnetic noise measured in the central building (CEB) at Virgo site [6]. We use the 90% magnetic percentile of data collected between Feb 10 2020 and Feb 16 2020 -during the second half of the third observing run, O3b.…”

“…They are expected to couple magnetically to gravitational-wave (GW) interferometers via, e.g. the mirror suspension systems, electric cables and the electronics, thereby inducing a correlated signal of terrestrial origin [4][5][6][7].…”

Environmental noise in advanced LIGO detectors

“…We also summarize how GW events are vetted using quantitative results from injections. This paper focuses on noise investigations at the LIGO detectors; a similar discussion for the Virgo detectors is provided in Fiori et al (2020) [9].…”

Application of Spatio-Temporal Spectral Analysis for Detection of Seismic Waves in Gravitational-Wave Interferometer

“…The method presented in this paper enables the identification of such signals. This characterization can help noise mitigation, especially for Newtonian noise coming from fluctuating gravitational forces caused by density perturbations of the ground and of the atmosphere [7][8][9][10]. The data for this paper are seismic data of Newtonian noise array of the seismic sensors installed at west-end building (WEB) of the Virgo GW detector [11].…”