First Einstein@Home Newsletter

Four times a year, project scientists and developers will tell you about our exciting science. In each newsletter, a handful of Einstein@Home team members will report on what they have been up to, and what their plans for the future are.

News on the gravitational-wave search (M. Alessandra Papa)
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The Einstein@Home all-sky search for continuous gravitational-wave signals in LIGO data, in the frequency range of 50 to 450 Hz, has given us over 16 million candidates to follow-up in LIGO S6 data. A first stage follow-up is currently running on Einstein@Home and should end soon. We have already lined up the next step: a second-stage follow-up of the most promising (some millions) of these candidates. This second stage inspects the candidates much more closely, and reduces the uncertainty in the signal parameters by about 90%. This second follow-up digs deeper into the detector noise, and will significantly increase the sensitivity of our search. This is very exciting because it is the first large scale deep follow-up we have ever performed!

In addition to these all-sky searches, Einstein@Home is also searching for continuous gravitational waves from specific targets in the sky. For the next stage of this, studies are ongoing to determine the optimal search set-up, the most promising target astrophysical objects, and the appropriate frequency and frequency-derivative search ranges. The next Einstein@Home targeted-search runs will be based on the results on these studies.

Here is the complete newsletter for all of you who cannot wait for the email to arrive :-)

News on the gravitational-wave search (M. Alessandra Papa)
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The Einstein@Home all-sky search for continuous gravitational-wave signals in LIGO data, in the frequency range of 50 to 450 Hz, has given us over 16 million candidates to follow-up in LIGO S6 data. A first stage follow-up is currently running on Einstein@Home and should end soon. We have already lined up the next step: a second-stage follow-up of the most promising (some millions) of these candidates. This second stage inspects the candidates much more closely, and reduces the uncertainty in the signal parameters by about 90%. This second follow-up digs deeper into the detector noise, and will significantly increase the sensitivity of our search. This is very exciting because it is the first large scale deep follow-up we have ever performed!

In addition to these all-sky searches, Einstein@Home is also searching for continuous gravitational waves from specific targets in the sky. For the next stage of this, studies are ongoing to determine the optimal search set-up, the most promising target astrophysical objects, and the appropriate frequency and frequency-derivative search ranges. The next Einstein@Home targeted-search runs will be based on the results on these studies.

News on the binary radio pulsar search (Benjamin Knispel)
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Einstein@Home is currently analyzing data from two different radio telescopes. The BRP4 run is searching data taken very recently with the Arecibo radio telescope as part of the PALFA survey. This is an ongoing survey: once we catch up with the backlog of observational data, the search is paused, and resumes when new data arrives. The BRP5 run that was analyzing data from the Parkes radio telescope, taken in the so-called "Perseus Arm surveyâ€, has recently finished. So far, we have identified several weak candidates, but sadly, attempts to re-observe them with the Parkes radio telescope revealed that they were all false alarms.

The latest binary radio pulsar search, called BRP6, is a further analysis of archival observations from the Parkes Telescope, from the very successful Parkes Multi-beam Pulsar Survey (PMPS). Previous Einstein@Home analysis of this data searched for pulsar spinning up to 130 rotations per second, and led to the discovery of 24 new pulsars (http://arxiv.org/abs/1302.0467). This new analysis, based on improvements in the Einstein@Home GPU apps, will go up to 300 Hz. This is interesting territory: fast-spinning pulsars in short-orbital-period binaries are extremely exciting astronomical objects, which enable precise tests of general relativity with them and studies of stellar evolution and the pulsar population in our Galaxy. We feel sure that more treasures remain to be uncovered!

News on the gamma-ray pulsar search (Holger Pletsch)
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Recently, we developed advanced methods (http://arxiv.org/abs/1408.6962) to improve the sensitivity of blind searches for unknown gamma-ray pulsars in data from the Large Area Telescope on board NASA's Fermi Satellite, which was launched in 2008. These techniques boost the sensitivity significantly: we can now detect gamma-ray pulsars that are 50% fainter than before, without increasing the computational cost! Our latest Einstein@Home run, FGRP4, makes use of these improvements to conduct a new blind survey of unidentified, pulsar-like Fermi sources.

The combination of improved methods, with the extra sensitivity of the latest Fermi data, makes us optimistic that we will make new discoveries. In fact we have already identified a large number of highly significant pulsar candidates and are currently carefully studying them.

News from the project administration (Bernd Machenschalk)
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We had a busy time around the end of last year! The locality scheduling for the new gravitational-wave analysis turned out to require much more attention than expected. We were very busy moving data around and improving the locality scheduler - and still are. Before the holidays we tried to get the entire project in a shape where it could survive without us -- we wanted to be with our families and friends and not busy keeping the project running. But it turned out that we had underestimated the progress that Einstein@Home would make: we got an unexpected boost of computing power over the holidays, and ran out of "work"! Fortunately this was easily fixed.

More importantly, there was to a bug in our server monitoring, which resulted in one of the Einstein@Home servers filling up without any warning. The affected server holds the uploaded result files from all Einstein@Home clients. Its file system was filled to the brim, which had severe consequences for the project. It took about a week to get the project running again smoothly. This was the first unplanned long downtime of Einstein@Home for quite a number of years. We did use the downtime for some improvements, which mean that the server is now working better than ever before!

Finally, some security issues turned up (the widely discussed gethostbyname() or "GHOST" problem) that needed urgent attention, and required updating and rebooting about 20 project servers.

Thank you for your continued support,
Bruce Allen, Benjamin Knispel, Bernd Machenschalk, M. Alessandra Papa, and Holger Pletsch
for the Einstein@Home team