Along this track, a detection of a TeV halo around Geminga
has recently been reported in : in that paper a naive estimate of the diffusion coefficient in the vicinity of Geminga
is presented, which turns out to be much smaller than the average galactic one inferred by secondary-to-primary ratios, posing a challenge both to CR transport models and to the pulsar interpretation of the positron anomaly as well; see also the follow-up detailed discussion in .
Holt (NASA-Goddard Space Flight Center) have detected pulsed X-ray emissions from Geminga
, a point source of high-energy gamma rays that has defied explanation for 20 years....
Despite these similarities, however, Geminga
was seen emitting gamma-ray pulses with no bright radio emission, while B0355+54 is one of the brightest radio pulsars known yet without a visible gamma ray signature.
To explain the observations of Geminga
, a model of a dense neutron star with localized protons was proposed [29,30].
Felber was also an officer at Geminga
Medical, Inc., a medical software company in which he developed and sold a software application that calculated impairment of the upper extremity of the human body.
In the July 31 Physical Review Letters, the team suggests that the source of the electron-positron excess could be Geminga
, a rapidly rotating stellar corpse known to emit gamma rays.
Using the Chandra X-ray Observatory, Bettina Posselt (Penn State University) and colleagues studied two very different pulsars, Geminga
(left) and B0355+54, both of which are surrounded by clouds of X-ray-emitting particles, called pulsar wind nebulae, that are swept back by the pulsars' passage.
The protons may also get their energy from a nearby pulsar, such as Geminga
, a relatively young pulsar surrounded by a highly magnetized nebula capable of generating high-energy particles.
"Powerful new observatories almost always solve longstanding astronomical mysteries.
, as the source became named, evaded detection with optical and radio telescopes of that era because it emits about 99% of its energy as gamma rays.
Another team, led by John Mattox of Boston University, analyzed the motion of a very different type of star, an extremely compact X-ray and gamma-ray emitter known as Geminga
. The rapidly rotating remnant of a supernova explosion from 300,000 years ago, Geminga
acts like a lighthouse beacon, regularly beaming radiation toward Earth.
A mysterious object called Geminga
(for Gemini gamma-ray source) has turned out to be a pulsar.