The telescope is severely under-appreciated for its achievements

Jul 7, 2009 21:01 GMT  ·  By
This photo shows pulsed gamma rays from the Vela pulsar as constructed from photons detected by Fermi's Large Area Telescope. A single pulsar cycle is repeated four times
   This photo shows pulsed gamma rays from the Vela pulsar as constructed from photons detected by Fermi's Large Area Telescope. A single pulsar cycle is repeated four times

In studies published in the July 2nd advanced online issue of the journal Science, teams of astronomers around the world have joined efforts in an attempt to complete a thorough analysis of more than two dozen pulsars observed by the Fermi Gamma-Rays Space Telescope. Of those 24 pulsars, 16 were discovered by the observatory alone, based solely on their gamma-ray signatures, and without relying on radio-wavelength telescopes for assistance.

“Fermi has truly unprecedented power for discovering and studying gamma-ray pulsars. Since the demise of the Compton Gamma Ray Observatory a decade ago, we've wondered about the nature of unidentified gamma-ray sources it detected in our galaxy. These studies from Fermi lift the veil on many of them,” Naval Research Laboratory in Washington expert Paul Ray explains. He adds that a pulsar is the core of a collapsed massive star, which is highly magnetized and spinning very fast around itself. Thus far, more than 1,800 such formations have been identified in the Universe.

It's widely believed among astronomers that their signatures – as in the pulses of radiation that allow for their identification – are generated when the structures' poles emit radio radiation, at determined intervals. But the power of the pulsar is not a clear indicator that it would emit considerable amounts of radiation. For example, the Vela pulsar, which is widely regarded as the most energetic and persistent such formation in the known Universe, spins around itself about 11 times per second, but only emits one gamma-ray photon (the most energetic form of light) once every two minutes.

“That's about one photon for every thousand Vela rotations. From the faintest pulsar we studied, we see only two gamma-ray photons a day,” University of California in Santa Cruz (UCSC) expert Marcus Ziegler, a member of the team that reported the new findings in Science, explains. He also underlines the fact that not all pulsars around us have been identified, but only those whose poles are oriented towards our planet. Regularly, radio telescopes are the first to pick up the fluctuations, but, if they are on a different plane than our planet, then they remain hidden.