, astronomers view the bright gamma-ray pulses along the edge of the torus, but the radio beams near the jets point off to the sides and remain unseen.
If the team is right about Geminga
, not only would the excess cosmic rays be explained without invoking dark matter, but the finding would also mark the first time that astronomers have linked cosmic rays to any specific source in the sky.
, or some other nearby source, may also be the culprit generating high-energy electrons, such as those recently captured over Antarctica.
Several years ago, after a 20-year effort, astronomers finally thought they had linked the gammaray source known as Geminga
to an optical and X-ray counterpart [and] inferred that the object is an isolated neutron star.
Combining 1970s observations of Geminga
taken by the COS-B satellite with new data taken by the Compton Gamma Ray Observatory, Mattox found a tiny variation in the arrival time at Earth of gamma rays emitted by the compact body.
Lastly, the putative planet around the high-energy gamma-ray source Geminga
is now believed to be an artifact of a change in that unusual pulsar's spin period, says Boston University astronomer John Mattox, who announced its provisional discovery two years ago.
The pulsar Geminga
now has a competitor for the title of nearest known pulsar to Earth.
Mattox (Boston University) at a meeting of gamma-ray astronomers in Williamsburg, Virginia Mattox and his colleagues used an instrument aboard the Compton Gamma Ray Observatory (GRO) to time clocklike blips from Geminga
, an enigmatic pulsar roughly 500 light-years from Earth.
The explosive birth of the powerful gamma-ray emitter Geminga
-- until recently one of the most mysterious objects in the heavens -- could have pushed gas out of the nearby interstellar medium and created the bubble, says Neil Gehrels of NASA's Goddard Space Flight Center in Greenbelt, Md.
Some 300,000 years ago a supernova explosion probably created this bubble, along with the nearby pulsar, Geminga
Unlike the other two sources, associated with the Crab and Vela pulsars, Geminga
apparently showed no pulsations and no traces of accompanying X-rays, radio waves or visible-light emissions.
The object was dubbed Geminga
, a contraction of Gemini gamma-ray source that also means "there's nothing there" in a Milanese dialect.