USRA | The Mystery of Part-Time Pulsars
http://www.usra.edu/news/pr/2017/pulsar/
A new discovery has upended the widely held view that all pulsars are orderly ticking clocks of the universe.
A survey done at the Arecibo Observatory in Puerto Rico has fortuitously discovered two extremely strange pulsars
that undergo a "cosmic vanishing act." Sometimes they are there, and then for very long periods of time, they are not.
Recognizing the existence of this strange behavior was fortuitous in itself. It took great patience on the part of
a team of radio astronomers at Jodrell Bank in the UK led by Professor Andrew Lyne of the University of Manchester
to confirm the existence of these mostly invisible pulsars.
Intermittent pulsars are a rarely observed population of pulsars, which have two states -- one when they pulse like
normal pulsars (the ON state), and another when they mysteriously fail to work, producing no radio waves at all (the
OFF state). "They switch instantaneously between the states," notes Lyne. "They're ON and then they're gone,
disappearing without any apparent warning."
A 34-member pulsar study team, including Dr. Andrew Seymour, a USRA postdoc at Arecibo, used the 7-beam receiver to
conduct routine pulsar searches in what they call the PALFA (Pulsar Arecibo L-Band Feed Array) Survey. The two recently
discovered intermittent pulsars spend most of their time in the OFF state. Three other similar pulsars are also known,
but they are mostly ON.
