A joint search for gravitational wave bursts with AURIGA and LIGO

Abstract

The first simultaneous operation of the AURIGA detector 63 and the LIGO observatory 64 was an opportunity to explore real data, joint analysis methods between two very different types of gravitational wave detectors: resonant bars and interferometers. This paper describes a coincident gravitational wave burst search, where data from the LIGO interferometers are cross-correlated at the time of AURIGA candidate events to identify coincident transients. The analysis pipeline is tuned with two thresholds, on the signal-to-noise ratio of AURIGA candidate events and on the significance of the cross-correlation test in LIGO. The false alarm rate is estimated by introducing time shifts between data sets and the network detection efficiency is measured by adding simulated gravitational wave signals to the detector output. The simulated waveforms have a significant fraction of power in the narrower AURIGA band. In the absence of a detection, we discuss how to set an upper limit on the rate of gravitational waves and to interpret it according to different source models. Due to the short amount of analyzed data and to the high rate of non-Gaussian transients in the detectors' noise at the time, the relevance of this study is methodological: this was the first joint search for gravitational wave bursts among detectors with such different spectral sensitivity and the first opportunity for the resonant and interferometric communities to unify languages and techniques in the pursuit of their common goal.

Gravitational waves: Sources, detectors and searches

“…Other all-sky burst searches in the last decade have included joint searches with the TAMA detector [146] (in addition to a joint coalescence search [145]), with the AURIGA detector [224] and with the GEO 600 detector [225]. In addition, there have been special searches for high-frequency bursts [226] (central frequency in the range 1 − 6 kHz in S5 data and for cosmic string cusp bursts [227] (see section 2.4) in S4 data.…”

The thermal history of the plasma and high-frequency gravitons

“…Since ν bbn < ν LV < ν max the wide-band interferometers are an ideal instrument to investigate the relic graviton spectrum in the unknown territory where there are neither direct nor indirect tests on the thermal history of the plasma. The problem is that, as it will be carefully shown, the spectral energy density of the relic gravitons produced within the ΛCDM model is quite minute and it is undetectable by interferometers even in their advanced version where the sensitivity is expected to improve by 5 or even 6 orders of magnitude in comparison with the present performances [34,35,36] (see also [37] and [38]). This impasse, as previously stressed, stems from the assumption that, right after inflation, the radiation-dominated evolution kicks in almost suddenly.…”

Stochastic backgrounds of relic gravitons: a theoretical appraisal

“…Since ν bbn < ν LV < ν max , wide-band interferometers represent an ideal instrument to investigate the relic graviton spectrum at high-frequencies. The spectral energy density of the relic gravitons produced within the ΛCDM model is quite minute and it is undetectable by interferometers even in their advanced version where the sensitivity is expected to improve by 5 or even 6 orders of magnitude in comparison with the present performances [63,64,65] (see also [66] and [67]). In Fig.…”