Bing Zhang (Physics and Astronomy) and a team of researchers recently published a paper in Nature Astronomy. The paper is titled, and was led by former 51ԹϺ Ph.D. student Bin-Bin Zhang.
In the paper, the research team discovered for the first time a change of the composition of the gamma-ray burst (GRB) jet in one source, dubbed GRB 160625B. GRBs are the most luminous explosions in the universe, marking the birth of a black hole when a massive star collapses or two compact stars merge.
A collimated “jet,” whose composition is poorly known, is launched from the system and travels toward Earth with a speed greater than 0.99995 speed of light, which is observed as a burst of gamma-rays. In the past, there has been a debate regarding whether the jet is mostly made of matter we are familiar with (which is called a “fireball”) or strong alternating magnetic and electric magnetic fields (which is called a Poynting-flux-dominated flow).
The Nature Astronomy paper, which is co-authored by 54 people from 39 institutions, reported a detailed observation of a bright burst GRB 160625B, which has three clearly-separated emission episodes. A detailed analysis by the team suggests that the jet composition of the burst clearly transitions from a fireball in the first episode to a Poynting outflow in the second episode. The results shed light on the poorly known explosion mechanism of these mysterious events.
