Astropulse

Astropulse is a distributed computing project that is searching for primordial black holes, pulsars, and ETI, using the Berkeley Open Infrastructure for Network Computing (BOINC) platform. In 1999, the Space Sciences Laboratory launched Seti@Home, which would rest on massively parallel computation on desktop computers scattered around the world. SETI@home utilizes recorded data from the Arecibo radio telescope and searches for narrow bandwidth radio signals from space, signifying the presence of extraterrestrial technology. It was soon recognized that this same data might be scoured for other signals of value to the astronomy and physics community.

For about 6 years, Astropulse existed in an experimental Beta testing phase not available to the general community. In July of 2008, Astropulse was integrated into SETI@home, so that the massive network of SETI participants could also contribute to the search for other astronomical signals of value. Astropulse also makes contributions to the search for ET. First, project proponents believe it may identify a different type of ET signal not identified by the original Seti@Home algorithm. Second, proponents believe it may create additional support for SETI by providing a second possible concrete result from the overall search project. Its as if someone sent you upstairs to find a lost book, and said, while you are up there, look around for my missing watch. Two searches for the price of one.

Astropulse searches for both single pulses and regularly repeating pulses. This experiment represents a new strategy for SETI, postulating microsecond timescale pulses as opposed to longer pulses or narrowband signals. They may also discover pulsars and exploding primordial black holes, both of which would emit brief wideband pulses. The primary purpose of the core Astropulse algorithm is coherent de-dispersion [1] of the microsecond radio pulses for which Astropulse is searching. Dispersion of a signal occurs as the pulse passes through the interstellar medium (ISM) plasma, because the high frequency radiation goes slightly faster than the lower frequency radiation. [2] Thus, the signal arrives at the radio-telescope dispersed depending upon the amount of ISM plasma between the Earth and the source of the pulse. Dedispersion is computationally intense, thus lending itself to the distributed computing model.

Astropulse utilizes the distributed computing power of SETI@home, delegating computational sub-tasks to hundreds of thousands of volunteers' computers, to gain advantages in sensitivity and time resolution over previous surveys. Wideband pulses would be "chirped" by passage through the interstellar medium; that is, high frequencies would arrive earlier and lower frequencies would arrive later. Thus, for pulses with wideband frequency content, dispersion hints at a signal's extraterrestrial origin. It searches for pulses with dispersion measures ranging from 50 pc cm-3 to 800 pc cm-3 (chirp rates of 7000 Hz to 400 Hz per microsecond) allowing detection of sources almost anywhere within the Milky Way.

Final development of astropulse has been a two-part endeavor. The first step was to complete the astropulse C++ core that can identify successfully a target pulse. Upon completion of that program, the team created a trial dataset that contained a hidden pulse, which the completed program successfully found, thus confirming the ability of the astropulse C++ core to successfully identify target pulses.

The BOINC idea is to divide (split) large blocks of data into smaller units, each of which can be distributed to individual participating work stations. To this end, the project then began to embed the Astropulse C++ core into the Seti Beta client and began to distribute real data, split into astropulse work units, to a team of beta testers. The challenge has been to assure that the astropulse core will work seemlessly on a broad array of operating systems.

Project proponents believe that Astropulse will either detect exploding black holes, or establish a maximum rate of 5 x 10^-14 pc^-3 yr^-1, a factor of 104 better than any previous survey. [3] The future of the project depends on extended funding to SETI@home.

Primordial Black Holes

"According to the Big Bang Model (also called the Standard Model), during the first few moments after the Big Bang, pressure and temperature were extremely great. Under these conditions, simple fluctuations in the density of matter may have resulted in local regions dense enough to create black holes. Although most regions of high density would be quickly dispersed by the expansion of the universe, a primordial black hole would be stable, persisting to the present." Wikipedia Primordial Black Holes One goal of Astropulse is to detect postulated mini black holes that might be evaporating due to "Hawking radiation". Such mini black holes [4] are postulated to have been created during the big bang, unlike currently known black holes. Martin Rees has theorized that a black hole, exploding via Hawking radiation, might produce a signal that's detectable in the radio. The Astropulse project hopes that this evaporation would produce radio waves that Astropulse can detect. "The evaporation wouldn't create radio waves directly. Instead, it would create an expanding fireball of high energy gamma rays and particles. This fireball would interact with the surrounding magnetic field, pushing it out and generating radio waves." [5]

RRAT's

Rotating radio transients (RRATs) are a newly discovered (as of 2006) type of neutron stars. RRAT's are believed to produce radio emissions which are are very difficult to locate, because of their transient nature. [6] Early efforts have been able to detecting radio emissions, sometimes called an RRAT flash, [7], for less than one second a day, and like other single burst signals, one must take great care to distinguish them from terrestrial radio interference. Distributing computing and the astropulse algorithm may thus lend itself to further detection of RRAT's.

External links

Related websites

• Astropulse Science
• Astropulse FAQ
• Website
• SETI@Home forum thread about Astropulse
• SETI@Home Beta forum thread about Astropulse
• Astropulse Wiki