NICER / ISS Science Nugget
for November 5, 2020

FR/GR/B

On April 28, 2020, a supermagnetized stellar remnant known as a magnetar blasted out a simultaneous mix of X-ray and radio signals never observed before. The flare-up included the first "fast radio burst" (FRB) ever seen from within our Milky Way galaxy, and shows that magnetars can produce these mysterious and powerful radio blasts previously only seen in other galaxies. NICER played an important role in this discovery and its interpretation, as reported in a NASA press release.

Thanks to ISS infrastructure that affords rapid target-of-opportunity (TOO) follow up, NICER observed the magnetar, SGR 1935+2154, within a few hours of a report of enhanced activity by NASA's Swift observatory. NICER detected roughly 200 X-ray bursts during a 20-min observation window. Thirteen hours later, the Canadian CHIME radio observatory and the Jet Propulsion Laboratory's STARE2 experiment detected a millisecond-duration radio burst, similar to past FRBs, but from the direction of SGR 1935 and with unprecedented brightness. X-ray and gamma-ray observatories detected a burst at the same time; unfortunately, SGR 1935 was inaccessible to NICER at the time of the simultaneous radio/X-ray burst.

This unique result involving NICER and other observatories from around the world demonstrates that magnetars, the strongest magnets in the universe, are responsible for at least some FRBs. NICER's spectroscopic and timing data (see figure) from the SGR 1935 "burst storm" inform a new model for the first Milky Way FRB, involving emission from near the star's magnetic pole, that has been submitted for publication.