Space and Earth Sciences News

Two studies published in Science Express show the analysis of gamma-rays from two dozen pulsars, including 16 discovered by  NASA's Fermi Gamma-ray Space Telescope. Fermi is the first spacecraft able to identify pulsars by their gamma-ray emissions alone. A pulsar is the rapidly spinning and highly magnetized core left behind when a massive star explodes. Most of the currently cataloged pulsars, some 1800 of them, were found through their periodic radio emissions; pulses caused by narrow, lighthouse-like radio beams emanating from the pulsar's magnetic poles, according to current theory. read more

"These are the first pulsars ever detected by gamma rays alone, and already we've found 16," said coauthor Robert Johnson, professor of physics at the University of California, Santa Cruz. "The existence of a large population of radio-quiet pulsars was suspected prior to this, but until Fermi was launched, only one radio-quiet pulsar was known, and it was first detected in x-rays."
"From the faintest pulsar we studied, the LAT sees only two gamma-ray photons a day," Ziegler said.
"It's been a longstanding question what could be powering those unidentified sources, and the new Fermi results tell us that a lot of them are pulsars," Saz Parkinson said. "These findings are also giving us important clues about the mechanism of pulsar emissions."
"This favors models in which the gamma rays are emitted from the outer magnetosphere of the pulsar, as opposed to the polar cap much closer to the surface of the star," Saz Parkinson said.
"Fermi has truly unprecedented power for discovering and studying gamma-ray pulsars," said Paul Ray of the Naval Research Laboratory in Washington.