Einstein@Home

Einstein@Home
Einstein@Home logo
Einstein@Home interactive screensaver
Project
Status	Active
Category	Astrophysics
Compute	CPU & GPU
Requires	None
Development
Developer	Bruce Allen
Author	Bruce Allen
Sponsor	Max Planck Society
Maintainer	Einstein@Home team
Initial release	February 19, 2005  (21 years ago)
Completed	No
Repository	https://git.ligo.org/einsteinathome
Software
Written in	C, C++
Operating system	Windows, Linux, macOS, Android
Size	~50 MB
BOINC statistics
Stats as of	May 19, 2026  (0 years ago)
Performance	21 PFLOPS
Active users	14,531
Total users	1,061,585
Active hosts	24,489
Total hosts	8,237,726
Analytics
RAC	18,500,000
Credit/day	950,000
GPU performance	15 PFLOPS
CPU performance	6 PFLOPS
Metadata
Website	https://einsteinathome.org/
License	GPL-2.0-or-later

Einstein@Home is a volunteer distributed computing project that needs your help to find Neutron Stars via their electromagnetic and gravitational wave emission.

Wikipedia page

Einstein@Home

Why Einstein@Home?

During a lunchtime conversation in 1999, Bruce Allen and a friend were discussing an article that they read that day in The Los Angeles Times about SETI@home. The thought occurred that this would be a great way to supply computer cycles to tackle the data analysis problem that they had, but concluded that there would be very little public interest and the topic was dropped.

In 2004, the idea was revisited due to the upcoming event World Year of Physics 2005. The American Physical Society offered publicity and volunteers and after eventually connecting with David Anderson, who spread the excitement of BOINC, Einstein@Home was launched in February of 2005. [2]

Einstein@Home was officially launched on February 19, 2005 at the annual meeting of the American Physical Society, making it one of the earliest projects to run on the BOINC platform. The project has grown enormously since then — as of December 2023, more than 492,000 volunteers in 226 countries had participated, and users regularly contribute approximately 7.7 petaFLOPS of computational power — enough to rank Einstein@Home among the top supercomputers on the TOP500 list.

Since its founding, it has become one of the four largest volunteer computing projects in the world, by any metric: number of volunteers, computing power, or peer-reviewed scientific output.

Goal

Einstein@Home uses the idle time of computing devices to search for weak astrophysical signals from spinning neutron stars (often called pulsars) using data from the LIGO gravitational-wave detectors, the MeerKAT radio telescope, the Fermi gamma-ray satellite, as well as archival data from the Arecibo radio telescope.

The long-term goal is to make the first direct detections of gravitational-wave emission from spinning neutron stars. Gravitational waves were predicted by Albert Einstein a century ago, and were directly seen for the first time on September 14, 2015. This observation of gravitational waves from a pair of merging black holes opens up a new window on the universe, and ushers in a new era in astronomy.

Einstein@Home volunteers have already discovered more than 90 new neutron stars.

Neutron Star Illustration This artist's conception illustrates 1E 1207.4-5209, a neutron star with a polar hot spot and a strong magnetic field (purple lines).

Methods

Einstein@Home employs the following search methods:

• Gravitational Wave search

The gravitational wave emitted by a deformed spinning neutron star is very simple. It is almost perfectly monochromatic. This means that it has a single frequency (twice the rotation frequency of the neutron star). This instantaneous frequency decreases slowly over time as the spinning neutron star loses energy through the emission of gravitational (and, if it is a pulsar, electromagnetic) waves. If one were to observe the gravitational-wave emission while floating in space at rest relative to the rotating deformed neutron star, things would be easy. Finding nearly monochromatic gravitational waves in a noisy detector is straightforward: A simple Fourier analysis would quickly reveal the periodicity. But in reality, the actual search is much more complicated and computationally demanding. One of the main reasons: Our detectors are not at rest relative to the neutron star. They sit on the surface of the Earth, which rotates daily and orbits the Sun once a year: The detectors are moving relative to the neutron star. This causes a Doppler shift in the gravitational-wave frequency observed by the detectors. The strength of the Doppler effect depends on time (during a day and within a year) and on the position of the neutron star in the sky. The plot on the right shows a simulation of a continuous gravitational-wave signal received on Earth. You can observe the annual and daily Doppler effect modulations.

To describe a continuous gravitational-wave signal, four different parameters are required: the sky position (two parameters, for example: right ascension and declination), the gravitational-wave frequency (one parameter), and the change of the gravitational-wave frequency over time (one parameter, usually called spin-down). To search for a faint signal in noisy detector data, long stretches of data (covering months of observations) must be analyzed. If the parameters of the signal are unknown, many different possible parameter combinations must be tested: Suppose there's a signal with a certain frequency, spin-down, and position in the sky. This combination of parameters will tell you what the expected signal would look like. Now, check the detector data for the presence of the expected signal using Fourier analysis methods. If nothing is found, try again with a different combination of parameters. Such a search requires a very large number of parameter combinations. This is because, over time, even a tiny offset in one of the parameters would cause the search to potentially miss a signal hidden in the detector noise: Assume a frequency value just a little off from the true one, and the signal will not show up in the analysis. The same holds for offsets in sky position or spin-down. To minimize the chance of missing a hidden signal, the data is very finely combed using a large number of parameter combinations.

Einstein@Home conducts the most sensitive all-sky searches for continuous gravitational waves in existence. While no continuous gravitational-wave signal from a spinning neutron star has yet been detected, even non-detections carry astrophysical significance: each search sets improved upper limits on the strain amplitude from spinning neutron stars across the Milky Way.

• The Fermi Gamma-ray Pulsar search

Finding the periodic pulsations from gamma-ray pulsars is very difficult – even more so from the very fast millisecond pulsars. On average only 10 photons per day are detected from a typical pulsar by the LAT onboard the Fermi spacecraft. To detect periodicities, years of data must be analyzed, during which the pulsar might rotate tens of billions of times. For each photon one must determine exactly when during a single milliseconds rotation period it was emitted. This requires searching over long data sets with very fine resolution in order not to miss any signals. The computing power required for these "blind searches" – when little to no information about the pulsar is known beforehand – is enormous.

Since mid-2011, Einstein@Home has also analyzed data from the Fermi Gamma-ray Space Telescope. As of December 2023, this search has uncovered 39 previously unknown gamma-ray pulsars. The Fermi gamma-ray discoveries include the first millisecond pulsar visible only in gamma rays — a radio-quiet object that suggests an entirely new population of pulsars may exist hidden in unidentified Fermi sources.

• Radio Pulsar search

The search is a "blind search" because we do not know the exact distance, spin frequency, and orbital parameters of the radio pulsar that might be hidden in a data set. A wide range in these parameters must be searched to maximize detection probability.

Interstellar space is filled with clouds of gas and dust. Some of these clouds have temperatures of about 8,000 K and contain free electrons. These clouds will disperse radio waves travelling through them, meaning that higher radio frequencies arrive earlier than lower ones. The more electrons in the gas along the line of sight, the larger this time-delay. Radio telescopes observe a wide band of radio frequencies, so this dispersion has to be corrected for. Since the exact amount of dispersion depends on the unknown distance to the pulsar and the number of electrons along this distance we correct for 628 trial values of dispersion and search each of the resulting data sets independently. This process is called "dedispersion" and done on the Einstein@Home servers.

Since we are ignorant of the orbital parameters of the binary we have to try thousands of possible orbital templates, each corresponding to a different pattern of Doppler spinup and spindown. For each of these templates the data are corrected for the full Doppler effect of the corresponding orbit. This is the first step done on the computers attached to the project. The next step is to test whether there is a radio pulsar present in that data set on that (or a similar) orbit. This is done by using a frequency analysis (Fourier transform) that will recover the spin frequency without smearing.

Because the signals of radio pulsars are not sinusoidal but pulsed, the frequency analysis will show frequency components at the fundamental frequency (the intrinsic spin frequency) and at higher harmonics (integer multiples of the fundamental frequency). Summing these components is a well-known trick in pulsar searches and significantly increases the sensitivity of the search. This summation is the last step done on the users' computers. Finally a list of the most significant candidates is reported back to the Einstein@Home servers and analyzed by the project scientists.

As of December 2023, the radio pulsar search has discovered 55 previously unknown radio pulsars.

Einstein@Home interactive screensaver showing some known pulsars and the Supernova that they came from

Data Sources

Einstein@Home draws on data from several major observatories:

Observatory	Type	Role in Einstein@Home
LIGO (USA)	Gravitational-wave detector	Primary source for continuous gravitational-wave searches since 2005
MeerKAT (South Africa)	Radio telescope	Current source of radio pulsar survey data
Fermi LAT (Space)	Gamma-ray telescope	Source for gamma-ray pulsar searches since 2011
Arecibo Observatory (Puerto Rico)	Radio telescope (decommissioned 2020)	Archival data; site of first E@H pulsar discovery in 2010
Parkes Observatory (Australia)	Radio telescope	Past source; site of 24-pulsar discovery (2013)

Technical Infrastructure

Einstein@Home runs on the Berkeley Open Infrastructure for Network Computing (BOINC) platform, originally developed at the University of California, Berkeley by David Anderson. The BOINC software is released under the GNU General Public License version 2.

At any given time, Einstein@Home features approximately a dozen server machines coordinating tens of thousands of active volunteer computers. The volunteer clients download observational data, run computationally intensive analysis, and return candidate lists to the project servers for further vetting by scientists.

Supported platforms include:

• Windows
• macOS
• Linux
• Android (via the BOINC app on Google Play or the Amazon Appstore for Kindle Fire)

GPU computing is also supported, and in recent years GPU-accelerated searches have been used to discover new gamma-ray pulsars in binary systems.

Screensaver

When a task is running on a volunteer's computer, an interactive 3D screensaver can be displayed that shows the region of the sky currently being analyzed, plots the positions of known pulsars, and displays the supernovae remnants from which they originated. The screensaver is included in the BOINC client and requires no additional installation. Volunteers can activate it from the Tasks tab of the BOINC Manager using the "Show Graphics" option.

How to Participate

The BOINC platform logo. Einstein@Home runs on BOINC, originally developed at UC Berkeley.

Joining Einstein@Home is free and requires only a few steps:

1. Create a free account at einsteinathome.org
2. Download and install the BOINC client from boinc.berkeley.edu
3. In the BOINC Manager, select Tools → Add Project, then choose Einstein@Home or enter the URL: https://einsteinathome.org

Your computer will automatically download work units, perform calculations, and report results back to the project when an internet connection is available. Volunteers can configure how much CPU time and memory BOINC may use, and can opt to run only when the computer is idle or plugged into power.

Android users can participate via the BOINC app available on the Google Play Store and the Amazon Appstore. The app computes only when the device is plugged into a power source and the battery is sufficiently charged.

Project team / Sponsor

Einstein@Home was founded and is directed by Bruce Allen of the Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Hanover, Germany, and the University of Wisconsin–Milwaukee.

Einstein@Home is a World Year of Physics 2005 and an International Year of Astronomy 2009 project. It is supported by the American Physical Society (APS), the US National Science Foundation (NSF), the Max Planck Society (MPG), and a number of international organizations.

See the list of contributors

One in six of Einstein@Home's neutron star discoveries were made by researchers at the Max Planck Institute for Gravitational Physics.

Scientific Discoveries

einsteinathome.org/science/discoveries

Einstein@Home has achieved numerous landmark scientific discoveries since its launch:

First Pulsar Discovery by Volunteer Computing (2010)

On 12 August 2010, Einstein@Home announced the discovery of PSR J2007+2722, a 40.8 Hz isolated pulsar found in archival data from the Arecibo Observatory taken in February 2007. This was the first genuine astronomical discovery by any public volunteer distributed computing project. The lucky volunteers whose computers identified the pulsar were Chris and Helen Colvin of Ames, Iowa, and Daniel Gebhardt of Universität Münster, Germany.

PSR J2007+2722 is most likely a disrupted recycled pulsar with a characteristic spin-down age of approximately 404 million years. Its pulse profile is remarkably wide, with emission over almost the entire spin period — making it a scientifically interesting object for understanding neutron star physics.

24 New Pulsars in Parkes Multi-beam Survey (2013)

Using the combined computing power of 200,000 volunteer PCs, Einstein@Home discovered 24 new pulsars in archival data from the CSIRO Parkes radio telescope in Australia. These included 18 isolated pulsars and 6 in binary systems, some with orbital periods of only a few hours. The results were published in The Astrophysical Journal.

First Gamma-ray Pulsars (2013)

On 26 November 2013, Einstein@Home published the first results from its Fermi data analysis: the discovery of four young gamma-ray pulsars in data from the Fermi LAT. This opened a new search channel for the project.

13 New Gamma-ray Pulsars (2017)

A large blind survey of 118 unidentified Fermi-LAT sources — a search that would have taken over 1,000 years on a single computer — was completed within one year using Einstein@Home computing power. The result: 13 new gamma-ray pulsars discovered, with two spinning slower than any previously known gamma-ray pulsar, and one having experienced a "glitch" — a sudden unexplained change in its rotation rate. The study was published in The Astrophysical Journal.

Double Neutron Star Binary: PSR J1913+1102 (2016)

Einstein@Home discovered PSR J1913+1102, a 27.3 ms pulsar in a 4.95-hour double neutron star binary system found in Arecibo PALFA survey data. With a total system mass of approximately 2.875 solar masses, it is among the most massive double neutron star systems known. Its relatively low eccentricity indicates an unusual formation history and provides new tests of general relativity.

First Radio-Quiet Millisecond Pulsar (2018)

Einstein@Home discovered two millisecond pulsars — PSR J1035−6720 (spinning 348 times per second) and PSR J1744−7619 (213 times per second) — in Fermi-LAT data. Follow-up observations with the Parkes Radio Telescope revealed that PSR J1744−7619 emits absolutely no detectable radio waves, making it the first radio-quiet millisecond pulsar ever discovered. Published in Science Advances.

Gamma-ray Black Widow Pulsar: PSR J1653−0158 (2020)

Using GPU-accelerated computing power donated by Einstein@Home volunteers, scientists discovered PSR J1653−0158, a 1.97 ms gamma-ray pulsar in a remarkably compact 75-minute binary orbit. This "black widow" pulsar had been a long-suspected source within the Fermi catalog. The discovery was made possible by novel GPU search algorithms running on volunteers' graphics cards.

Running Total

As of late 2023–2024:

• 55 radio pulsars discovered
• 39 gamma-ray pulsars discovered
• 90+ new neutron stars in total

Scientific Publications

einsteinathome.org/de/science/publications

The following is a selection of key peer-reviewed publications arising from Einstein@Home. A comprehensive list of all BOINC project publications is maintained at boinc.berkeley.edu/pubs.php.

Landmark Papers

• B. Knispel et al. (2010). "Pulsar Discovery by Global Volunteer Computing." Science 329, 1305. DOI: 10.1126/science.1195253 — First astronomical discovery by a volunteer computing project (PSR J2007+2722).

• B. Allen et al. (2013). "The Einstein@Home Search for Radio Pulsars and PSR J2007+2722 Discovery." The Astrophysical Journal 773(2). arXiv:1303.0028 — Full description of the radio pulsar search methodology and first discovery.

• B. Knispel et al. (2013). "Einstein@Home Discovery of 24 Pulsars in the Parkes Multi-beam Pulsar Survey." The Astrophysical Journal Letters 774(2). DOI: 10.1088/0004-637X/774/2/93

• B.P. Abbott et al. (2017). "First low-frequency Einstein@Home all-sky search for continuous gravitational waves in Advanced LIGO data." Physical Review D 96, 122004. — First Einstein@Home search of Advanced LIGO O1 data.

• C. J. Clark et al. (2017). "The Einstein@Home Gamma-ray Pulsar Survey I: Search Methods, Sensitivity and Discovery of New Young Gamma-ray Pulsars." The Astrophysical Journal. arXiv:1611.01015

• J. Wu et al. (2018). "The Einstein@Home Gamma-Ray Pulsar Survey II: Source Selection, Spectral Analysis and Multi-wavelength Follow-up." arXiv:1712.05395

• C. J. Clark et al. (2018). "Einstein@Home Discovers a Radio-quiet Gamma-ray Millisecond Pulsar." Science Advances. DOI: 10.1126/sciadv.aao7228

• B. Knispel et al. (2015). "Einstein@Home Discovery of a PALFA Millisecond Pulsar in an Eccentric Binary Orbit." arXiv:1504.03684 — Discovery of PSR J1950+2414, a 4.3 ms pulsar in an unusually eccentric 22-day orbit.

• L. Nieder et al. (2020). "Discovery of a Gamma-ray Black Widow Pulsar by GPU-accelerated Einstein@Home." arXiv:2009.01513 — Discovery of PSR J1653−0158 using volunteer GPU computing.

• P. C. C. Freire et al. (2016). "Einstein@Home Discovery of a Double-Neutron Star Binary in the PALFA Survey." arXiv:1608.08211 — Discovery of PSR J1913+1102.

Recognition and Scale

Einstein@Home was a flagship project of the World Year of Physics 2005.

Einstein@Home holds several notable distinctions:

• It was a flagship project of the World Year of Physics 2005, an international initiative marking the centenary of Einstein's annus mirabilis.
• It was also an official project of the International Year of Astronomy 2009.
• As of December 2023, it is the third-most-popular active BOINC application by volunteer participation.
• Its combined computing power (~7.7 petaFLOPS) would rank it among the top 105 supercomputers on the TOP500 list.
• It produced the first genuine astronomical discovery by any public volunteer distributed computing project — the radio pulsar PSR J2007+2722, announced in Science in 2010.

External Links

• Official Einstein@Home website
• Scientific discoveries
• Scientific publications
• Contributors
• Einstein@Home on Wikipedia
• Publications by BOINC Projects (boinc.berkeley.edu)
• Einstein@Home at the Max Planck Institute for Gravitational Physics
• Einstein@Home – gravitational waves for everybody (Einstein Online)