An international team of astronomers has produced an incredible series of observations of a gamma-ray burst (GRB) and the massive stellar explosion that was generated. The researchers managed to point several instruments at the event right as it happened, collecting crucial data for our understanding of these phenomena.
The GRB was observed by two NASA Gamma-Ray space telescopes, Fermi and Swift, that sent in real time the GRB location to observatories across the world, which were able to see the afterglow of the event almost has it happened. The rapid-response telescopes measured how the light of the explosion was polarized, basically in which direction it was oscillating.
As reported in Nature, the polarization of the light was as high as 30 percent – data that supports the idea that the system has a strong, stable, and globally ordered magnetic field, which might have played a crucial role in the emission of such an energetic and cataclysmic event.
"We think the gamma-ray emission is due to highly energetic electrons, propelled outward like a fireball,” co-author Nathaniel Butler from Arizona State University said in a statement.
He added: "This is the first strong evidence that the early shocks generated by these bursts are magnetically driven."
The researchers suggest that the supernova responsible for such a powerful GRB ended up in a black hole and that the gamma-ray emission is due to the black hole emitting jets. The gamma-ray emission is extremely collimated, only a few degrees in the sky, making us extremely lucky to detect it. We are looking down the barrel of this cosmic gun, but we are yet to see what’s pulling the trigger.
"Despite a long history of observations," Butler added, "the emission mechanism driving gamma-ray bursters remains largely mysterious."
"These are the brightest explosions in the universe. And we were able to measure this one's development and decay almost from the initial blast."
The GRB in this study was observed on June 25, 2016, and it released in just 40 seconds the energy our own Sun would produce over its entire lifetime. There’s about one gamma-ray detection a day from everywhere in the sky. They last between a handful of milliseconds to a minute, which is why they have so far kept their mystery.