2023-11-06 16:57:01
With Einstein@Home and Zooniverse, citizens can identify previously unknown pulsars from home
When large radio telescopes look for the regular blinking of neutron stars, which rotate very quickly on their own axis like cosmic lighthouses, they first collect large amounts of data that need to be sifted through. The very signals from such pulsars, which would help us to better understand fundamental physics, are too well hidden in the data and their analysis is very computationally expensive. Citizens can now help search for such hidden signals even better from home.
Cosmic lighthouse: A radio pulsar is a compact neutron star that accelerates charged particles to relativistic speeds in its extremely strong magnetic field. Radio waves (green) are emitted in a cone shape over the magnetic poles. The rotation pans the radio light cones across the radio telescope’s line of sight, causing the pulsar to periodically light up in the data.
© NASA/Fermi/Cruz de Wilde
Cosmic lighthouse: A radio pulsar is a compact neutron star that accelerates charged particles to relativistic speeds in its extremely strong magnetic field. Radio waves (green) are emitted in a cone shape over the magnetic poles. The rotation pans the radio light cones across the radio telescope’s line of sight, causing the pulsar to periodically light up in the data.
© NASA/Fermi/Cruz de Wilde
Shortly: Helping since 2009 Einstein@Home-Volunteers in analyzing observations from the Arecibo radio telescope to find new pulsars. The project’s research team has now pre-sorted these results, created a file with tens of thousands of promising pulsar candidates and produced a series of graphical, diagnostic representations for each of these possible new pulsars. Now is within the scope of the project „Pulsar Seekers“ once once more asked for the help of volunteers to complete the search and to identify previously unknown pulsars with absolute certainty and with the help of the prepared images.
Distributed thinking complements distributed computing
Since its launch in 2005, the Einstein@Home project has searched for and found new neutron stars and compact remnants of exploded massive stars by incorporating volunteers’ assessments and their home computing capabilities. The Max Planck Institute for Gravitational Physics (Albert Einstein Institute) in Hanover and the University of Wisconsin-Milwaukee are carrying out the project. “It has long been our plan to involve volunteers more closely in Einstein@Home and have them actively view and classify pulsar candidates,” says Bruce Allen, director of Einstein@Home and director at the Max Planck Institute for Gravitational Physics (Albert- Einstein Institute, AEI) in Hanover. Einstein@Home pools the otherwise unused computing power on the PCs of more than 15,000 volunteers, making it one of the largest projects of its kind in the world. Since 2009, Einstein@Home has evaluated data from the Arecibo radio telescope and discovered 31 new radio pulsars, a special type of neutron star , found. Now Einstein@Home is working with Zooniverse. This successful citizen science web portal allows volunteers to classify graphical representations of the Einstein@Home results to discover additional pulsars in the Arecibo data.
Neutron stars are compact remnants of supernova explosions and consist of extremely dense matter. They are regarding 25 kilometers wide and weigh more than our sun. Because of their strong magnetic fields and rapid rotation, they emit radio waves in narrow beams like a cosmic lighthouse. When these beams are aimed at Earth as the neutron star rotates, it becomes visible as a radio pulsar. Pulsars are excellent tools for astrophysics, enabling research in various areas of astronomy, such as testing Einstein’s general theory of relativity, understanding extremely dense matter, studying the thin gas between stars and our galaxy’s magnetic field, and searching for low-frequency gravitational waves .
To date, Einstein@Home has discovered 31 radio pulsars in data from the Arecibo telescope, 24 radio pulsars in data from Parkes Observatory in Australia, and 39 gamma-ray pulsars in data from NASA’s Fermi Gamma-ray Space Observatory. The long-term goal of the project is to discover the never-before-observed continuous gravitational waves from neutron stars.
On a treasure hunt in the heritage of Arecibo
The Zooniverse project Pulsar Seekers is analyzing data from the Arecibo radio telescope, seen here in an aerial view before its collapse in 2020.
© NAIC – Arecibo Observatory
The Zooniverse project Pulsar Seekers is analyzing data from the Arecibo radio telescope, seen here in an aerial view before its collapse in 2020.
© NAIC – Arecibo Observatory
In the search for new radio pulsars, telescopes such as the famous, now collapsed Arecibo radio telescope observed hundreds of thousands of positions in the sky for a few minutes each. Each of these observations must then be checked for the regular blinking expected from radio pulsars. Searching for pulsars alone in space can be done in a short time using a small number of computers. Searching for pulsars in close orbits is much more computationally intensive, but worthwhile. If researchers might measure two neutron stars orbiting each other in just a few minutes, they would be able to subject general relativity to the most precise tests yet.
The Einstein@Home volunteers and the computing power they provide to the project make such a search possible. When the volunteers’ computers finish analyzing an Arecibo observation, the end result of their collective efforts is a long list of nearly 400,000 candidates (possible pulsar signals), each described by a handful of numbers. As a rule, only one true pulsar is hidden among these candidates.
Separating wheat from chaff
For each pulsar candidate, Zooniverse volunteers look at a group of four diagrams like the one shown here. In a short guide you will learn how to distinguish a pulsar (like in this example) from terrestrial disturbances or random noise.
© Project “Pulsar Seekers”
For each pulsar candidate, Zooniverse volunteers look at a group of four diagrams like the one shown here. In a short guide you will learn how to distinguish a pulsar (like in this example) from terrestrial disturbances or random noise.
© Project “Pulsar Seekers”
“Einstein@Home has evaluated more than 150,000 observations from the Arecibo radio telescope,” says Alexandra Botnariuc from the Max Planck Institute for Gravitational Physics. “This results in the gigantic number of 60 billion pulsar candidates. There are far too many to study individually, and most of them are not true astrophysical signals anyway.” She developed and implemented an algorithm to reduce this number. The method detects similar candidates that are likely caused by the same astrophysical signal and identifies those that most closely resemble real pulsars.
At the start of the project, the research team created graphical representations of the 50,000 most promising Einstein@Home Pulsar candidates and launched a new citizen science project called “Pulsar Seekers”, which is operated via the Zooniverse platform. “The number of candidates is so large that one person cannot handle this task. Therefore, the collective effort of Zooniverse participants is invaluable in identifying real pulsars,” says Rahul Sengar, a research associate at the University of Wisconsin-Milwaukee who leads the Pulsar Seekers project. “We are very excited to see what the Zooniverse volunteers will discover in our data!”
The citizen scientists receive short and simple instructions on Zooniverse in which they learn how to distinguish real pulsars from nuisance signals. “If all goes well and several thousand Zooniverse volunteers take part in Pulsar Seekers, in just a few days they will be able to sift through our first 50,000 pulsar candidates, sort the wheat from the chaff and perhaps find some interesting new pulsars,” says Colin Clark from the Max Planck Institute for Gravitational Physics.
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