Prof. Bing Zhang and former UNLV students/postdocs published in Nature Publishing Group journals

Prof. Bing Zhang from Department of Physics and Astronomy published two papers in Nature Publishing Group journals recently: one in the 2018 January issue of Nature Astronomy (DOI:10.1038/s41550-017-0309-8) and the other in the upcoming issue of Nature Communications (DOI: 10.1038/s41467-018-02847-3). Both papers are led by former UNLV Ph.D. student Dr. Bin-Bin Zhang, who just finished a postdoctoral fellowship at Instituto de Astrofísica de Andalucía (IAA-CSIC), Spain (where the research reported in both papers was carried out) and joined the faculty of Nanjing University, China, as an associate professor. Prof. Zhang is the second and co-corresponding author of both papers.

In the Nature Astronomy paper, the 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 towards 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 within the community 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.

The most important discovery in astronomy in 2017 was the groundbreaking discovery of a gravitational wave event GW170817 due to the merger of two neutron stars as well as its associated short GRB 170817A and other electromagnetic counterpart emissions in multi-wavelength. The Nature Communications paper reports an independent analysis of the emission properties of GRB 170817A as well as the physical implications. This paper has 18 authors, including 4 former UNLV Ph.D. students (Drs. He Gao, Ye Li, Hou-Jun Lü besides Bin-Bin Zhang) and 3 former UNLV postdoc fellows (Drs. Wei-Hua Lei, Xue-Feng Wu, and En-Wei Liang) as the key authors. This paper nicely complements the official papers by the LIGO/Virgo gravitational wave detector team and the NASA’s Fermi Gamma-Ray Telescope team by studying the luminosity function of short GRBs as well as the possible physical mechanism that powers this unique event.