Sci. Adv. 4, eaao7228 (2018)

Millisecond pulsars are old neutron stars that spin hundreds of times per second and appear to pulsate when their emission beams are radiating towards their observers. Most of them emit radio waves and can be detected by radio telescopes. However, others — so-called radio-quiet pulsars — can only be sensed at higher unknown pulsation frequencies. Colin J. Clark and co-workers have performed ‘blind’ searches in the data obtained from the Large Area Telescope, the main instrument on the Fermi Gamma-ray Space Telescope launched in 2008, and discovered two isolated millisecond pulsars.

Without prior constraints from other observations, a completely blind search is computationally demanding. The analysis involves hundreds of thousands of sky locations covering the gamma-ray source localization region. Clark et al. split the search volume for each source into smaller regions, and distributed them among the computers of tens of thousands of volunteers participating in the Einstein@Home distributed-computing project. Using the aggregated power from these computers located across the globe, gamma-ray pulsations from two sources, identified as two millisecond pulsars, were finally revealed.