in the style of New Scientist

New gamma-ray eyes spot hidden pulsars

NASA’s new Fermi gamma-ray telescope has captured the faint gamma-ray glimmer of pulsars invisible to radio telescopes. The enhanced ability to detect pulsars may help theorists flesh out the life stories of massive stars.

Pulsars are spinning neutron stars, the dense and fiercely magnetized remnants of massive stars that underwent gravitational collapse. Astronomers can observe them with a radio telescope only when the slender streams of radio waves broadcast from their magnetic poles point Earthward. The newly identified pulsars appear to emit gamma-rays in broad plumes originating in their intense magnetic atmospheres well above the neutron stars’ surfaces.

The new pulsars weren’t simple to spot. To detect periodic patterns in emissions from extremely faint objects rotating at an unknown rate, a team led by the Santa Cruz Institute for Particle Physics (SCIPP) ran five months of data through a series of brute force guess-and-check calculations. Their computations turned up 16 pulsars rotating between 2 and 20 times per second (Science, DOI: 10.1126/science.1175558). Since then, they have identified at least 8 more. The newly discovered pulsars are 10,000 to 100,000 years old, young by astronomical standards.

“Certainly there are a lot that we haven’t seen,” says Robert Johnson, the SCIPP physicist who designed the telescope’s gamma-ray sensors. Astronomers have already identified more than 1800 radio pulsars, but Johnson said the new gamma-ray telescope may double the number of pulsars they can detect.

Caption: New pulsars: blink and you’ll miss them.