• Trio finds a pulsar ... and so can you

    Einstein @ Home / UW-Milwaukee

    The Einstein @ Home screensaver shows the source of the data being analyzed as an orange dot on a rotating celestial sphere.

    Three regular folks from Iowa and Germany are being credited with the discovery of a radio pulsar, spinning in space 17,000 light-years away, thanks to an unassuming screensaver program called Einstein @ Home.

    The program, which has been downloaded to 500,000 computers around the world over the past five years, almost literally turns volunteers into Einsteins at home. It's designed to download astronomical data, 2 megabytes at a time, and look for signs of gravity-wave bursts or radio pulsar flashes during times when the computer is otherwise idle.

    The pulsar discovery, announced today on the journal Science's website, marks the first time Einstein @ Home has had a hit. But it won't be the last. And it gives hope that even more ambitious distributed-computing projects such as SETI @ Home could eventually hit paydirt as well.

    "This is a thrilling moment for Einstein @ Home and our volunteers," project leader Bruce Allen, who is director of Germany's Max Planck Institute for Gravitational Physics (Albert Einstein Institute), said in a news release. "It proves that public participation can discover new things in our universe. I hope it inspires more people to join us to help find other secrets hidden in the data."

    The secrets of the pulsar were hidden within radio observations made by the Arecibo Observatory in Puerto Rico three years ago. The Einstein @ Home project was started five years ago to sift through data from the Laser Interferometer Gravitational-wave Observatory, or LIGO, looking for evidence that would confirm Albert Einstein's general theory of relativity. Last year, the project started including Arecibo data collected by the Pulsar ALFA consortium as well, just to give Einstein @ Home users an extra goal to shoot for.

    Triumph of the geeks
    The three people whose computers identified the pulsar, dubbed PSR J2007+2722 (or "J2007" for short), couldn't possibly have found it on their own. During a teleconference today, they freely admitted that they're no scientists. But they're not exactly computer newbies, either.

    A home computer owned by Chris and Helen Colvin of Ames, Iowa, was the first to flag the pulsar's ping on June 11. Both husband and wife are information-technology professionals. Chris, a systems architect for Wells Fargo Bank, said he installed Einstein @ Home on a "run-of-the-mill PC that I built a year or two ago." The machine is now sitting in his basement home office.

    Daniel Gebhardt, a systems administrator for the music informatics department at University of Mainz in Germany, also had the screensaver running on a personal computer. That computer had the same data package downloaded by the Colvins, but it took a few days longer to upload the confirming results. Allen explained that each package is run by two different users to verify the results. "Some of the results we get from one user are just wrong," he told me.

    At the time, neither the Colvins nor Gebhardt knew that there was a hit. Einstein @ Home just uploaded the data packages back to its servers. It took another month for all the data relating to J2007's area of the sky to be processed by all 314 volunteers working on different models for the data. But once all the results were analyzed, on July 11, the pulsar's presence stood out like a sore thumb. The Colvins and Gebhardt were "the people who saw the pulsar with the highest significance," Allen said.

    The next step was to confirm the pulsar's existence by checking the archives of astronomical data and making new telescope observations. The fact that the professionals were able to confirm J2007's location and get a paper published by Science in less than a month was an achievement in itself, said Cornell astronomer James Cordes, chair of the Pulsar ALFA consortium.

    Scientific breakthrough? Or spam?
    Allen got the word out to the Colvins and Gebhardt as soon as he could, via e-mail - but it took a while for the Colvins to get the message.

    "He tried to e-mail us for a few times," Chris Colvin said. "I've been busy this summer, and we neglected our e-mail."

    Allen tells a slightly different story. "It turns out that he thought the e-mails were spam," the professor told me. "If you get an e-mail that says you won a million dollars, you just delete it. I finally got his attention when I sent him a registered letter by FedEx."

    The Colvins and Gebhardt are acknowledged in a footnote to the paper detailing the pulsar discovery, which also thanks the 250,000 Einstein @ Home volunteers "who made this discovery possible." (On average, each volunteer has downloaded the screensaver program to two computers.)

    Not your typical pulsar
    It turns out that J2007, located in the Milky Way in the constellation Vulpecula, is not just any radio pulsar. Most pulsars are neutron stars that spin on their axis about once a second and have strong magnetic fields. In contrast, the J2007 neutron star spins 41 times a second, and has a weak magnetic field. This type of fast-spinning pulsar is usually associated with a binary-star system - but J2007 seems to be sitting out in space by itself.

    "Our understanding of neutron star populations is pretty good, but we don't understand everything," Cordes said.

    Based on the observations made since its discovery, astronomers surmise that J2007 was part of a double-star system that experienced dual explosions. First, J2007 went supernova, leaving the neutron star behind. Then the other star turned into a red giant, spraying material onto J2007. That additional material caused J2007 to spin up again, causing it to be "reborn as a fast rotator," Cordes said.

    When the second star went supernova, the binary system could have been disrupted, sending the two neutron stars on their separate ways. This would leave J2007 as what's known as a disrupted recycled pulsar. Such a scenario would explain the unusual behavior astronomers see today, Cordes said.

    There's more in the Einstein @ Home data where that came from: Cordes said yet another pulsar detection already has been made, and this time it's a binary system. Allen said the new discovery was made by screensaver users from Britain and Russia. The astronomers declined to provide further details, however, because the findings have not yet been confirmed by the professionals. The Einstein @ Home users don't even know yet that their data may contain a fresh discovery.

    Next steps for citizen science
    Allen said he hoped the find announced today will spark more Einstein @ Home downloads, and more discoveries to be gleaned from the mounting masses of data. "There might be the holy grail of the radio astronomer, which is a neutron star orbiting a black hole," he told me. "Who knows what else is in that data?"

    Einstein @ Home is just one of dozens of screensaver projects based on the BOINC distributed-computing platform, which was developed at the University of California at Berkeley's Space Sciences Laboratory. The first and most famous BOINC project is SETI @ Home, which has been sifting through Arecibo data for the past 11 years, looking for signals from alien civilizations. (None has been found yet, even though more than 5 million users have been looking.)

    Other BOINC projects include ClimatePrediction.net and the protein-folding screensaver known as Rosetta @ Home. (Another protein-folding experiment in citizen science, Foldit, made the news just last week.)

    You don't have to be an astronomer, or a biologist, or even a computer geek to participate. All you have to do is download and install a screensaver program that will do its work while your computer is sitting idle. "It's a very nice screensaver,"said Helen Colvin. "You get a rotating map of the stars, and other than that there isn't anything really we need to do with it."

    "It uses a little bit more energy - but why not, if it's in the interest of science?" Gebhardt said.

    Allen said about 100,000 computers connect to the Einstein @ Home servers every week to download data. "The point is that the collective computing power of all these computers around the world is actually substantially greater than the largest supercomputers that are built," he said. And cheaper for researchers, too.

    "It would cost something like $500 an hour in the United States, or about 1,000 euros an hour in Europe to run that size of a computation," Allen said. And that price tag is merely for the electrical power. It doesn't count the administrative costs, or the capital expense of actually buying the computers.

    "It's really quite a lot of value," Allen said. "Just the electrical costs alone, contributed by volunteers, work out to a few million dollars per year."

    The Colvins and Gebhardt won't be getting any of that money. But they will be getting snazzy wall plaques celebrating the pulsar discovery, as well as a far more precious payoff: the knowledge that they've made a milestone contribution to citizen science.

    "There are more discoveries out there," Chris Colvin said. "We need more CPU power to uncover them."

    In addition to Allen and Cordes, authors of the SciencExpress paper, "Pulsar Discovery by Global Volunteer Computing," include principal author Benjamin Knispel of the Albert Einstein Institute as well as J.S. Deneva, D. Anderson, C. Aulbert, N.D.R. Bhat, O. Bock, S. Bogdanov, A. Brazier, F. Camilo, D.J. Champion, S. Chatterjee, F. Crawford, P.B. Demorest, H. Fehrmann, P.C.C. Freire, M.E. Gonzalez, D. Hammer, J.W.T. Hessels, F.A. Jenet, L. Kasian, V.M. Kaspi, M. Kramer, P. Lazarus, J.van Leeuwen, D.R. Lorimer, A.G. Lyne, B. Machenschalk, M.A. McLaughlin, C. Messenger, D.J. Nice, M.A. Papa, H.J. Pletsch, R. Prix, S.M. Ransom, X. Siemens, I.H. Stairs, B.W. Stappers, K. Stovall and A. Venkataraman.

    Allen is an adjunct professor of physics at the University of Wisconsin at Milwaukee as well as head of the Albert Einstein Institute. The U.S. National Science Foundation supported this work through grants to the Einstein@Home project, to the PALFA project, to the BOINC project at the University of California at Berkeley, and through a cooperative agreement with Cornell University to operate the Arecibo Observatory. The Max Planck Institute for Gravitational Physics (Albert Einstein Institute) is supported by the Max Planck Society and the Leibniz Universität Hannover. NSF is providing a news release, an archived webcast of today's news briefing, graphic simulations of the pulsar's motion and an audio interpretation of the pulsar's radio signal waveform.

    An earlier version of this report provided an incorrect date for the completion of data analysis on the Colvins' computer.

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  • Rise of the robot astronomer

    NASA / ESA / Hubble Heritage (STScI / AURA)

    A Hubble Space Telescope picture of the Abell Cluster reveals a wide range of galactic diversity. A giant elliptical galaxy dominates the center of the image, but there's also a beautiful spiral at lower right and many smaller galaxies.

    When thousands of Internet users helped astronomers classify types of galaxies through a project called Galaxy Zoo, some of them may not have realized that they were training a machine to do their job.

    British astronomers say they used data from the project to develop a software algorithm for galaxy classification that matched the human-generated results 90 percent of the time. Such robot astronomers may well do the bulk of the work in future all-sky galactic surveys. But the research team's leader says we need not fear the rise of the machines: The point of the exercise is to liberate us humans to do the more interesting tasks.

    The University of Cambridge's Manda Banerji explained that celestial surveys to come will have to analyze hundreds of millions of galaxies. Banerji herself is involved in one of those surveys, the Dark Energy Survey, which will look at 300 million galaxies over five years, starting in 2011. Another project known as the VISTA Hemisphere Survey will take pictures of galaxies over the entire southern celestial hemisphere.

    "We're getting to that age where we can't viably do these things using the human eye," Banerji told me today.

    In the coming age, improved image-classification software could handle the no-brainers first. "The idea is that if we can eliminate all the things that are pretty standard, and we can give humans just the 10 percent that's left, then we're only bothering the humans to look at the interesting objects," Banerji said.

    Galaxy Zoo's organizers were co-authors on the latest study, which is already available in preprint and is set to appear in the Monthly Notices of the Royal Astronomical Society. So it doesn't come as any surprise to them that the fruits of their labors are being used to build better software. Thanks to Internet tools, 250,000 users of the Galaxy Zoo website have already checked 60 million galaxies and contributed to 16 scientific papers. In some cases, Galaxy Zoo users have even been listed as co-authors of those papers.

    Getting a statistical handle on the cosmic distribution of galaxies is one of the big challenges for astrophysics today: How many are elliptical, or spiral, or clumpy and irregular? Does that distribution change with age? What other characteristics can be correlated with galaxy structure? Such questions could lead to hugely important answers: For instance, the Dark Energy Survey is designed to look for clues in galactic data that could help solve the mystery surrounding the universe's accelerating expansion.

    The software developed by Banerji and her team attacks the galaxy-classification challenge using a method that's different from the tried-and-true human approach. Instead of merely eyeballing the shape of a specific galaxy, the algorithm looks at qualities such as color, brightness variations and texture. A reddish galaxy is more likely to be an elliptical, for example, while a bluish galaxy is more likely to be a spiral.

    The researchers fed the software a database of galaxies with known shapes, and trained the software to match up those shapes with the other qualities. The fully trained software was then used to classify a bigger database of galaxies on its own, and the machine's verdict matched the humans' verdict more than 90 percent of the time. The other 10 percent tended to be relative oddballs - for example, a bluish galaxy that for some reason is elliptical.

    The next step is to figure out what other qualities can be used to classify the oddballs correctly, and then upgrade the software. Or just outsource the job to a human.

    In addition to Banerji, the authors of the paper appearing in the Monthly Notices of the Royal Astronomical Society, "Galaxy Zoo: Reproducing Galaxy Morphologies Via Machine Learning," include Ofer Lahav of University College London, Chris J. Lintott of the University of Oxford, Filipe B. Abdalla (UCL), Kevin Schawinski (Yale), Steven P. Banford (University of Nottingham), Dan Andreescu (LinkLab), Phil Murray (Fingerprint Digital Media), M. Jordan Raddick (Johns Hopkins), Anze Slosar (Brookhaven National Lab), Alex Szalay (Johns Hopkins), Daniel Thomas (University of Portsmouth) and Jan Vandenberg (Johns Hopkins).

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