Upper limits on gravitational wave bursts in LIGO’s second science run

Abstract

We perform a search for gravitational wave bursts using data from the second science run of the LIGO detectors, using a method based on a wavelet time-frequency decomposition. This search is sensitive to bursts of duration much less than a second and with frequency content in the 100 -1100 Hz range. It features significant improvements in the instrument sensitivity and in the analysis pipeline with respect to the burst search previously reported by LIGO. Improvements in the search method allow exploring weaker signals, relative to the detector noise floor, while maintaining a low false alarm rate, O0:1 Hz. The sensitivity in terms of the root-sum-square (rss) strain amplitude lies in the range of h rss 10 ÿ20 ÿ 10 ÿ19 Hz ÿ1=2 . No gravitational wave signals were detected in 9.98 days of analyzed data. We interpret the search result in terms of a frequentist upper limit on the rate of detectable gravitational wave bursts at the level of 0.26 events per day at 90% confidence level. We combine this limit with measurements of the B. ABBOTT et al.PHYSICAL REVIEW D 72, 062001 (2005) 062001-2 detection efficiency for selected waveform morphologies in order to yield rate versus strength exclusion curves as well as to establish order-of-magnitude distance sensitivity to certain modeled astrophysical sources. Both the rate upper limit and its applicability to signal strengths improve our previously reported limits and reflect the most sensitive broad-band search for untriggered and unmodeled gravitational wave bursts to date.

Search for gravitational-wave bursts in LIGO data from the fourth science run

“…Comparisons with previous LIGO [16,17] and LIGO-TAMA [8] searches have already been shown graphically in figure 12. The LIGO-TAMA search targeted millisecond-duration signals with frequency content in the 700-2000 Hz frequency regime (i.e., partially overlapping the present search) and had a detection efficiency of at least 50% (90%) for signals with h rss greater than ∼2 × 10 −19 Hz −1/2 (10 −18 Hz −1/2 ).…”

“…Although we did not measure the sensitivity of the S4 LIGO search with narrow-band signals at 1300 Hz, LIGO's noise at that frequency range varies slowly enough so that we do not expect it to be significantly worse than the sensitivity for 1053 Hz sine-Gaussian signals described in section 7, which stands at about 7 × 10 −21 Hz −1/2 . Comparisons with results from resonant mass detectors were detailed in our previous publications [16,17]. The upper limit of ∼4 × 10 −3 events day −1 at the 95% confidence level on the rate of gravitational wave bursts set by the IGEC consortium of five resonant mass detectors still represents the most stringent rate limit for h rss signal strengths of order 10 −18 Hz −1/2 and above [36].…”

“…As in previous searches [17,18], the WaveBurst algorithm [20] is used for this purpose; it will only be summarized here [21].…”

“…This analysis uses LIGO data from the fourth science run carried out by the LSC, called S4, and uses the same basic methods as previous LSC burst searches [17,18] that were performed using data from the S2 and S3 science runs. (A burst search was performed using data from the S1 science run using different methods [16].)…”

A joint search for gravitational wave bursts with AURIGA and LIGO

“…Over the past decade, the search for these signals has been independently performed by individual detectors or by homogeneous networks of resonant bars [4] or laser interferometers [5][6][7][8][9]. The first coincident burst analysis between interferometers with different broadband sensitivity and orientation was performed by the TAMA and LIGO Scientific Collaborations [10].…”