Null-stream veto for two co-located detectors: Implementation issues

TL;DR

This paper discusses implementing a null-stream veto for two co-located gravitational wave detectors, addressing calibration uncertainties and correlated noise, and proposes a new formulation tested with software injections.

Contribution

It introduces a new formulation of the null-stream veto that accounts for calibration uncertainties and correlated noise in a two-detector network.

Findings

Calibration uncertainties impact null-stream veto effectiveness

Proposed formulation improves veto reliability under uncertainties

Software injections validate the new approach

Abstract

Time-series data from multiple gravitational wave (GW) detectors can be linearly combined to form a null-stream, in which all GW information will be cancelled out. This null-stream can be used to distinguish between actual GW triggers and spurious noise transients in a search for GW bursts using a network of detectors. The biggest source of error in the null-stream analysis comes from the fact that the detector data are not perfectly calibrated. In this paper, we present an implementation of the null-stream veto in the simplest network of two co-located detectors. The detectors are assumed to have calibration uncertainties and correlated noise components. We estimate the effect of calibration uncertainties in the null-stream veto analysis and propose a new formulation to overcome this. This new formulation is demonstrated by doing software injections in Gaussian noise.