Not only is the resulting image the deepest picture of the neutron star collision’s afterglow to date, it also reveals secrets about the origins of the merger, the jet it created and the nature of shorter gamma ray bursts.
Starting in December 2017, NASA’s Hubble Space Telescope detected the visible light afterglow from the merger and revisited the merger’s location 10 more times over the course of a year and a half.
Fong, Blanchard and their collaborators approached the challenge by using all 10 images, in which the kilonova was gone and the afterglow remained as well as the final, deep Hubble image without traces of the collision.
The result: a final time-series of images, showing the faint afterglow without light contamination from the background galaxy.
With the Hubble’s deep space image, Fong and her collaborators gleaned new insights about GW170817’s home galaxy.
According to the new image, Fong also believes that distant, cosmic explosions known as short gamma ray bursts are actually neutron star mergers — just viewed from a different angle.
The study, “The optical afterglow of GW170817: An off-axis structured jet and deep constraints on a globular cluster origin,” was primarily supported by the National Science Foundation (award numbers AST-1814782 and AST-1909358) and NASA (award numbers HST-GO-15606.001-A and SAO-G09-20058A).