11. Typical S3 results

Shown in the figures below is typical output from the final post-processing step. It shows, in a band from 300 to 325 Hz, and for each grid point in the sky, the maximum number of ten-hour data segments for which the value of 2F exceeded 25. Because there were sixty different ten-hour data segments, this number could range from 0 to 60.

The first figure, Fig. 11.1 (a), shows the declination - right ascension color map of the maximum number counts at each grid point on the sky. The second figure, Fig. 11.1 (b), shows the declination - frequency color map of the maximum number counts at each grid point on the sky. These two figures show that over the entire sky we have no prominent candidates in the 300-325 Hz frequency band. This band is one of the typical clean bands in our S3 LIGO Hanford detector data. The majority of frequency bands are as clean as this example.

Figure 11.1: Color map of the number of coincidences among sixty 10-hour data segments for the frequency range 300 to 325 Hz. (a) All-sky map. (b) frequency-declination plane.

(a) All-sky map	(b) declination - frequency map

The most benign type of instrumental noise (Gaussian noise) would produce a number count of around 6 by random chance. For this type of noise, any candidates having number counts larger than, say, 20 would be potential candidates for further follow-up studies.

In this frequency band (from 300 to 325 Hz) the largest number of segments that contained a consistent signature of a pulsar was found to be 6, consistent with Gaussian noise. In contrast to this, a very strong pulsar signal would have appeared in all, or nearly all, of the 60 segments. A source near our threshold for detection would have appeared in many (say, more than half) of the segments. This was illustrated in the section on hardware/software injection for some "fake" sources added to the data set.

Based on this plot, we conclude that Einstein@Home did not find any credible candidates or disturbances in the frequency band from 300 to 325 Hz.

The full results of the Einstein@Home run on S3 (from 50 to 1500 Hz) are summarized in section 14.

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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