Artist's impression of SGR 1935+2154, a highly magnetised stellar remnant, also known as a magnetar.
Discovered in 2014 in the constellation of Vulpecula following a substantial burst of X-rays, the magnetar became active again in April 2020. ESA's Integral high-energy space observatory detected a burst of high-energy, or ‘hard’, X-rays on 28 April, automatically alerting observatories worldwide about the discovery in just seconds. Soon after, astronomers spied something astonishing: this magnetar was not only radiating its usual X-rays, but radio waves, too.
This unique mix of radiation, never before seen bursting from such a stellar remnant, may solve a long-standing cosmic mystery about the nature of Fast Radio Bursts – powerful events that pulse brightly in radio waves for just a few milliseconds before fading away, and are only rarely seen again.