Astronomers have discovered the fastest-spinning pulsar in our galactic disc, making it the second-fastest known — and they did it using gaming technology.
Pulsars are small, rapidly spinning neutron stars left over after a star roughly eight times more massive than our own sun dies in a supernova, a spectacular stellar explosion. As pulsars rotate, particles are ejected along their poles.
And while “normal” pulsars rotate tens of times per second, there are millisecond pulsars that can rotate hundreds of times per second, something astronomers didn’t even think was possible until the first discovery made in 1982.
The newly discovered pulsar, PSR J0952-0607, is one such millisecond pulsar, rotating at a breakneck speed of 707 times per second. It is second only to one in a dense star cluster outside of our disc that rotates 716 times per second.
The discovery was made using radio telescopes at the Low-Frequency Array (LOFAR) in the Netherlands. Ziggy Pleunis, co-author of the findings published in The Astrophysical Journal Letters, who is now a PhD student at McGill University, told CBC News.
What’s particularly interesting to astronomers is just how precise pulsars — just the size of small cities — are.
‘Very stable’ rotation
“They rotate so quickly … like this at 707 times per second, and this rotation is very stable and it only changes maybe one part in a million, or even less per second,” Pleunis said. “So we can use them as tools, as clocks in the sky.”
Pulsars shine brightest at low frequencies, something LOFAR is well suited to seeing. However, the dust between the stars gets in the way, making the work challenging.
So astronomers at LOFAR used a processing technique using graphics cards originally designed for gaming, which Pleunis said is efficient.
Gaming processing units, or GPUs, were designed for 3D games, but are also programmable and can handle multiple computations at once.
So the astronomers used data collected by NASA’s Fermi Gamma-ray Space Telescope (pulsars give off high electromagnetic radiation in the form of gamma rays) together with GPUs in a computer cluster called DRAGNET, which processes LOFAR data.
“The techniques are not new, in the sense that people thought of these techniques in the ’70s already,” Pleunis said.
“But it’s always been too hard and no one had a computer that could do that. And nowadays, because these gaming cards are so cheap, it’s now possible to do these kinds of calculations.”
They novel method worked: it first detected a pulsar rotating at 412 times per second.
“It was really nice that it worked,” Pleunis said. “The most surprising thing was when we finally made the discovery.”
The astronomers were able to illustrate that radio waves from the pulsar were arriving at the same time as the gamma rays, which suggests there is some mechanism in the star that is produce both types of radiation.
Searching for even more speed
Pleunis hopes the new findings will lead to discoveries of more millisecond pulsars, perhaps some that rotate even faster.
“The most important part about this is that it will teach us about the extremes in the universe,” Pleunis said.
“We do these surveys because, once in a while, some interesting pulsar pops up that no one had expected, or does something strange that no one had expected, and that tells us about physics.”