Multi-wavelength view of the close-by GRB 190829A sheds light on gamma-ray burst physics

Understand

Gamma-ray bursts are produced as a result of cataclysmic events such as the collapse of a massive star or the merger of two neutron stars.

• We monitored the position of the close-by gamma-ray burst GRB~190829A, which originated from a massive star collapse, through very long baseline interferometry (VLBI) observations with the EVN and the VLBA, involving a total of 30 telescopes across 4 continents.
• We carried out a total of 9 observations between 9 and 117 days after the gamma-ray burst at 5 and 15 GHz, with a typical resolution of few milliarcseconds (mas).
• We obtained limits on the source size and expansion rate.