After we initially analyzed the S3 data set, we made several improvements:
This final re-analysis of S3 was completed in August 2005 (then followed by a long period in which the results and analysis tools were reviewed and vetted). The following two plots in Fig. 14.1 summarize the results of YOUR Einstein@Home analysis of the LIGO S3 data.
We see in this figure that, once we have removed the injected, fake pulsar signals, there are no significant candidates left outside of the "noisy belt", which was described in section 12. Candidates on the "noisy belt" have to be discarded, because such candidates would be produced by line-noise artifacts of the detector, as discussed in sections 12 and 13. There are still eight surviving low-significance candidates outside of the "noisy belt", even after removal of the injected pulsars. These low-significance candidates were ruled out either by a followup analysis using S4 data, or by subsequent identification as noise-artifacts (e.g. one candidate was found to be associated with a 70.12 Hz oscillator in one of the VME electronics crates connected to the interferometer instrumentation).
We therefore conclude that we have not seen any credible evidence for pulsar signals in the Einstein@Home search on S3 data. This is not surprising. The LIGO instruments were still undergoing commissioning to reach their design sensitivity at the time of the S3 science run. And even at design sensitivity, the level of noise in the instruments is high enough that it may obscure gravitational wave signals present in the data.
Whether or not we can detect something in the future depends upon nature, luck, and our ability to improve the detector and our analysis methods. Much progress has been made since the S3 analysis. This progress and our plans for the future are discussed in the next section.
Einstein@Home S3 Analysis Summary
Last Revised: 2007.03.28 08:59:23 UTC
Copyright © 2005 Bruce Allen for the LIGO Scientific Collaboration
Document version: 1.132