NASA | GSFC | Fermi | 2019 Dec 19
NASA’s Fermi Gamma-ray Space Telescope has discovered a faint but sprawling glow of high-energy light around a nearby pulsar. If visible to the human eye, this gamma-ray “halo” would appear about 40 times bigger in the sky than a full Moon. This structure may provide the solution to a long-standing mystery about the amount of antimatter in our neighborhood.Fermi Finds Vast 'Halo' Around Nearby Pulsar ~ Credit: NASA/GSFCClick to play embedded YouTube video.
“Our analysis suggests that this same pulsar could be responsible for a decade-long puzzle about why one type of cosmic particle is unusually abundant near Earth,” said Mattia Di Mauro ... “These are positrons, the antimatter version of electrons, coming from somewhere beyond the solar system.” ...
For the past decade, cosmic ray measurements by Fermi, NASA’s Alpha Magnetic Spectrometer (AMS-02) aboard the International Space Station, and other space experiments near Earth have seen more positrons at high energies than scientists expected. Nearby pulsars like Geminga were prime suspects. ...
The team determined that the Fermi LAT data were compatible with the earlier HAWC observations. Geminga alone could be responsible for as much as 20% of the high-energy positrons seen by the AMS-02 experiment. Extrapolating this to the cumulative emission from all pulsars in our galaxy, the scientists say it’s clear that pulsars remain the best explanation for the positron excess. ...
Detection of a γ-ray Halo Around Geminga with the Fermi-LAT Data and
Implications for the Positron Flux ~ Mattia Di Mauro, Silvia Manconi, Fiorenza Donato
- Physical Review D 100(12):3005 (15 Dec 2019) DOI: 10.1103/PhysRevD.100.123015
- arXiv.org > astro-ph > arXiv:1903.05647 > 13 Mar 2019
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