Page 7 - UNAM Forum ED2-2021

Front-row view reveals

exceptional cosmic explosion

Observation challenges established theory

of gamma-ray bursts in the universe

front row when this gamma-ray co-author Edna Ruiz-Velasco by separate mechanisms: the
burst happened,” explains co- from the Max Planck Institute for X-ray component originates
author Andrew Taylor from DESY. Nuclear Physics in Heidelberg. “This from ultra-fast electrons that are
The team caught the explosion’s is what’s so exceptional about this deflected in the strong magnetic
afterglow immediately when it gamma-ray burst – it happened in fields of the burst’s surroundings.
became visible to the H.E.S.S. our cosmic backyard where the This “synchrotron” process is quite
telescopes. “We could observe very-high-energy photons were similar to how particle accelerators
the afterglow for several days and not absorbed in collisions with on Earth produce bright X-rays for
to unprecedented gamma-ray background light on their way to scientific investigations.
energies,” reports Taylor. Earth, as it happens over larger
distances in the cosmos.” However, according to existing
The comparatively short distance theories, it seemed very unlikely
to this gamma-ray burst allowed The team could follow the that even the most powerful
detailed measurements of the afterglow up to three days explosions in the universe could
afterglow’s spectrum, which is the after the initial explosion. The accelerate electrons enough to
distribution of “colours” or photon result came as a surprise: “Our directly produce the observed
energies of the radiation, in the observations revealed curious very-high-energy gamma rays. This
very-high-energy range. “We similarities between the X-ray and is due to a “burn-off limit”, which
could determine GRB 190829A’s very-high-energy gamma-ray is determined by the balance Image of gamma-ray burst taken by HESS (Credit HESS)
spectrum up to an energy of 3.3 emission of the burst’s afterglow,” of acceleration and cooling of
tera-electronvolts, that’s about reports Zhu. Established theories particles within an accelerator.
a trillion times as energetic as the assume that the two emission Producing very-high-energy
photons of visible light,” explains components must be produced gamma rays requires electrons

7 Official Newsletter ...continued on pg 8