Gamma-ray bursts (GRBs) are immensely energetic explosions
VERN BENDER
Gamma-ray bursts (GRBs) are immensely energetic explosions that have been observed in distant galaxies. The intense radiation of most observed GRBs is thought to be released during a supernova or superluminous supernova as a high-mass star implodes to form a neutron star or a black hole.
Analysis of a recent GRB afterglow showed that both components, X-ray and gamma-ray, faded in sync. Also, the gamma-ray spectrum clearly matched an extrapolation of the X-ray spectrum. This indicates that X-rays and very-high-energy gamma rays in this afterglow were produced by the same mechanism. Regular detections in the very high-energy band will become rather common.
Some of these explosions occur when a massive star — five or 10 times the mass of our sun — detonates, abruptly becoming a black hole. Gamma-ray bursts may also occur when two superdense stellar corpses called neutron stars to collide, often forming a black hole. And conveniently, a gamma-ray burst that scientists watched during a few nights in 2019 likely occurred only about 1 billion light-years away from Earth, relatively close by for these dramatic events.
It happened in our cosmic backyard, where the very-high-energy photons were not absorbed in collisions with background light on their way to Earth, as happens over larger distances in the cosmos.
The patterns of X-rays and very high-energy gamma-rays matched — something scientists wouldn’t expect since they believe different phenomena cause the two different types of radiation.
Long gamma-ray bursts are bright flashes of extragalactic gamma rays produced during the collapse of a massive star. A gamma-ray burst itself lasts only a few seconds but is followed by an afterglow that can persist for hours or days.
By adding infinitely many twists to the curves on a sphere, it’s possible to crush it down to a tiny ball without distorting its distances.
The general abundance of gamma-ray bursts leads us to expect that regular detections in the very-high-energy band will become rather common, helping us to fully understand their physics
.You can crumple a sphere down to a ball of any size without ever creasing it. This made it possible a new type of geometric object called an “embedding,” which situates a shape inside a larger space — not unlike fitting a two-dimensional poster into a three-dimensional tube. There are lots of ways of embedding a shape. Some preserve the shape’s natural form — like rolling the poster into a cylinder, while others crease or tear it to make it fit in different ways.
