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.

The GEO 600 gravitational wave detector uses advanced technologies including signal recycling and monolithic fused-silica suspensions to achieve a sensitivity close to the kilometre scale LIGO and VIRGO detectors. As soon as the design sensitivity of GEO 600 is reached, the detector will be operated as part of the worldwide network to acquire data of scientific interest. The limited infrastructure at the GEO site does not allow for a major upgrade of the detector. Hence the GEO collaboration decided to improve the sensitivity of the GEO detector by small sequential upgrades some of which will be tested

We use 373 hours ( 15 days) of data from the second science run of the LIGO gravitational-wave detectors to search for signals from binary neutron star coalescences within a maximum distance of about 1.5 Mpc, a volume of space which includes the Andromeda Galaxy and other galaxies of the Local Group of galaxies. This analysis requires a signal to be found in data from detectors at the two LIGO sites, according to a set of coincidence criteria. The background (accidental coincidence rate) is determined from the data and is used to judge the significance of event candidates. No inspiral gravitational-wave events were identified in our search. Using a population model which includes the Local Group, we establish an upper limit of less than 47 inspiral events per year per Milky Way equivalent B. ABBOTT et al. PHYSICAL REVIEW D 72, 082001 (2005) 082001-2 galaxy with 90% confidence for nonspinning binary neutron star systems with component masses between 1 and 3M .

We report on a search for gravitational waves from binary black hole inspirals in the data from the second science run of the LIGO interferometers. The search focused on binary systems with component masses between 3 and 20M . Optimally oriented binaries with distances up to 1 Mpc could be detected with efficiency of at least 90%. We found no events that could be identified as gravitational waves in the 385.6 hours of data that we searched.B. ABBOTT et al.

We report on the first joint search for gravitational waves by the TAMA and LIGO collaborations. We looked for millisecond-duration unmodeled gravitational-wave bursts in 473 hr of coincident data collected during early 2003. No candidate signals were found. We set an upper limit of 0.12 events per day on the rate of detectable gravitational-wave bursts, at 90% confidence level. (2005) 122004-3 simulations, we estimate that our detector network was sensitive to bursts with root-sum-square strain amplitude above approximately 1-3 10 ÿ19 Hz ÿ1=2 in the frequency band 700-2000 Hz. We describe the details of this collaborative search, with particular emphasis on its advantages and disadvantages compared to searches by LIGO and TAMA separately using the same data. Benefits include a lower background and longer observation time, at some cost in sensitivity and bandwidth. We also demonstrate techniques for performing coincidence searches with a heterogeneous network of detectors with different noise spectra and orientations. These techniques include using coordinated software signal injections to estimate the network sensitivity, and tuning the analysis to maximize the sensitivity and the livetime, subject to constraints on the background.