So far, we have not seen any evidence for pulsar signals in the S3 data. As described earlier, this is not surprising, because LIGO is not sensitive enough to guarantee that we will see one or more pulsars. This depends upon luck: the location, shape, orientation and spin rate of the nearest pulsars to the Earth.
Starting in late June 2005 we have begun to repeat this analysis using the highest quality part of the complete LIGO/GEO S4 data set. A significant difference is that this new S4 analysis uses data from both the LIGO Hanford (H1) and the LIGO Livingston (L1) instruments. We expect that this new analysis should be completed by fall 2005.
In late summer 2005 we hope to begin a new and improved S4 analysis similar to the previous analysis but focusing on a narrower frequency band (probably about 500 Hz wide) and using a longer coherent integration time for computing the F statistic. Work is now underway to build and test a new Einstein@Home application for this purpose. This application contains a new algorithm for placing pulsar templates in parameter space. We anticipate being able to use coherent integration times of thirty to fifty hours in this search, thus obtaining a higher level of sensitivity (at fixed detector noise levels) than in the S3 search described here, and in the currently-underway S4 search.
The initial LIGO detectors are scheduled to begin a series of long data runs (S5) in late 2005, operating for the first time at their design sensitivity. As the initial LIGO interferometers start to search for the first gravitational wave signals, the LIGO Lab, the LIGO Scientific Collaboration, and international partners are beginning work on an Advanced LIGO upgrade [40] to improve the sensitivity by more than a factor of 10. Since the volume of space that the instrument can see grows as the cube of the distance, this means that the event rates will be 100 to 1,000 times greater than for initial LIGO.
This new detector will be installed in the existing LIGO vacuum system at the LIGO Hanford and Livingston Observatories. This upgrade will replace the present detector after the present detector has reached its goal of a year of observation at design sensitivity. Advanced LIGO will transform gravitational wave science into a real observational tool. It is anticipated that this new instrument will discover new gravitational wave sources as often as once per day, with excellent signal strength, allowing details of the waveforms to be read off and compared with theories of neutron stars, black holes, and other highly relativistic objects.
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Einstein@Home S3 Analysis Summary |
Last Revised: 2005.09.11 16:22:17 UTC |
Copyright © 2005 Bruce Allen for the LIGO Scientific Collaboration
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Document version: 1.97 |