Fermi Revolutionizes Pulsar Knowledge

Astronomers at NASA are thrilled that, following the launch of the new Fermi Gamma-ray Space Telescope, new pieces of information about the make-up of pulsars are coming up for the first time in 40 years. Since these unusual stars were first discovered, scientists have wondered as to what their actual power is, seeing how other telescopes could only pick up limited amounts of data and supply enough information for estimative numbers. Now, Fermi is looking at dozens of pulsars, discovering new exciting sets of information each day, and relaying them back for analysis.

"We know of 1,800 pulsars, but until Fermi we saw only little wisps of energy from all but a handful of them. Now, for dozens of pulsars, we're seeing the actual power of these machines," Stanford University in California pulsar astronomer Roger Romani, who is part of the team analyzing the new data, explains. He and colleagues presented the finds at the 213th meeting of the American Astronomical Society (AAS) in Long Beach, California, in December 2008.

He says that it's only now that astronomers are finally getting some thorough insight into how these celestial bodies operate, and into how exactly the stars emit their waves of electromagnetic radiation. Furthermore, some of these neutron stars also seem to be generating their charges from well above the actual surface of the celestial body, which is a feat no one had any idea about. Thus far, Fermi identified about a dozen pulsars that only emit gamma-ray, alongside tens of other such bodies.

Romani argues that new data will keep flowing in, and that "a new era of high-energy pulsar physics" is on its way, as we speak. The new data, which recently reached the American space agency, is only the "first wave of such discoveries."

"We used to think the gamma rays emerged near the neutron star's surface from the polar cap, where the radio beams form. The new gamma-ray-only pulsars put that idea to rest," Alice Harding, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, reveals. Some emissions are now thought to emanate from an altitude as high as 300 miles above a pulsar, although some are just 20 miles in diameter themselves. This "puts the nail in the coffin of the classic polar cap model," Romani concludes.