An artist's depiction of the Fermi Space Telescope detecting gamma-rays released by pulsars. (Image credit: Daniëlle Futselaar/MPIfR (artsource.nl))
Telescopes that observe the universe in the most energetic form of light may help scientists detect the "fingerprints" of gravitational waves, new research reveals.
Gravitational waves form when massive objects such as black holes collide, creating ripples in space-time that wash over Earth. Although current gravitational wave observatories, such as the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo interferometer, can detect the violent collisions that result in gravitational waves, these observatories can see only one of those events at a time, often months apart.
But there may be another way to find gravitational waves: by looking for their fingerprints in pulsars, rapidly spinning neutron stars that pulsate at regular intervals.
Now, researchers think they have illuminated the path toward that goal in a new study, thanks to observations by NASA's Fermi Gamma-ray Space Telescope, which observes the universe in gamma-rays, the most energetic form of light.
"We've been surprised at how good it is at finding the types of pulsars we need to look for these gravitational waves — over 100 so far!" study co-leader Matthew Kerr, a physicist at the U.S. Naval Research Laboratory, said in a statement.
Pulsars rotate at very precise intervals, and scientists can track those intervals from Earth thanks to the beams pulsars emit. As gravitational waves wash over a pulsar, they might subtly alter those pulsars' timing, and astrophysicists think they can observe those subtle changes and thus trace the gravitational waves that created them.
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Traditionally, astronomers find pulsars by using radio telescopes to scour the sky for radio waves. But the gas and dust that fill the cosmos are not kind to radio waves; many of them get absorbed en route.
Gamma-rays, by contrast, are the highest-energy of any wave on the electromagnetic spectrum, meaning they'll get through. But until this new study, astrophysicists had never really used gamma-rays to track pulsars. The results may mean there's a new, more powerful way to find pulsars and, in turn, detect gravitational waves, and researchers hope future improvements will make these detection methods even more sensitive.
The research is described in a paper published April 7 in the journal Science.
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Rahul Rao is a graduate of New York University's SHERP and a freelance science writer, regularly covering physics, space, and infrastructure. His work has appeared in Gizmodo, Popular Science, Inverse, IEEE Spectrum, and Continuum. He enjoys riding trains for fun, and he has seen every surviving episode of Doctor Who. He holds a masters degree in science writing from New York University's Science, Health and Environmental Reporting Program (SHERP) and earned a bachelors degree from Vanderbilt University, where he studied English and physics.
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