Astrophysics – Marshall Science Research and Projects Division

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Astrophysics – Marshall Science Research and Projects Division

Dr. Daniel Kocevski gave an invited talk on the high-energy detection of GRB 190114C at a conference held in Yokohama, Japan.  The talk focused on the Fermi and Swift contributions to a paper reporting the first very high-energy detection of a gamma-ray burst (GRB) by ground-based air Cherenkov telescopes.  The detection gave high-energy astrophysicists a better understanding of accelerated mechanisms that generate the gamma-rays from these events.  The paper has been accepted for publication in the journal Nature.

On January 14, 2019, just before 4:00 p.m. EST, both the Fermi Gamma-ray Space Telescope and the Neil Gehrels Swift Observatory detected a spike of gamma rays from the constellation Fornax.  These distant explosions have produced the highest-energy light yet seen from these events, called gamma-ray bursts, or GRBs.  The missions alerted the astronomical community to the location of the burst, dubbed GRB 190114C.

One facility receiving the alerts was the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) observatory located on La Palma in the Canary Islands, Spain.  Both of its 17-meter telescopes automatically turned to the site of the facing burst.  They began observing the GRB just 50 seconds after it was discovered and captured the most energetic gamma rays yet seen from these events.  With GRB 190114C, MAGIC became the first facility to report unambiguous very high-energy (VHE) emission, with energies up to a trillion electron volts (1 TeV). That’s 10 times the peak energy Fermi has seen to date.

Scientists suspect that most of the gamma rays from GRB afterglows originate in magnetic fields at the jet’s leading edge.  High-energy electrons spiraling in the fields directly emit gamma rays through a mechanism called synchotron emission.  But other scientists, including the MAGIC team, interpret the VHE emission as a distinct afterglow component, which means some additional process must be at work, perhaps inverse Compton scattering.  High-energy electrons in the jet crash into lower-energy gamma rays and boost them to much higher energies.


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Astrophysics – Marshall Science Research and Projects Division

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