STRANGE RADIO SIGNAL NEAR THE CENTRE OF THE MILKY WAY HAS SCIENTISTS STUMPED

Astronomers have detected a strange, repeating radio signal near the centre of the Milky Way, and it’s unlike any other energy signature ever studied. The energy source is extremely finicky, appearing bright in the radio spectrum for weeks at a time and then completely vanishing within a day. This behaviour doesn’t quite fit the profile of any known type of celestial body, according to researchers, and thus may represent “a new class of objects being discovered through radio imaging”.

The radio source, known as ASKAP J173608.2−321635, was detected with the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope, situated in the remote Australian outback. In an ASKAP survey taken between April 2019 and August 2020, the strange signal appeared 13 times, never lasting in the sky for more than a few weeks. This radio source is highly variable, appearing and disappearing with no predictable schedule, and doesn’t seem to appear in any other radio telescope data prior to the ASKAP survey.

When the researchers tried to match the energy source with observations from other telescopes – including the Chandra X-ray Observatory and the Neil Gehrels Swift Observatory, as well as the Visible and Infrared Survey Telescope for Astronomy in Chile, which can pick up nearinfrared wavelengths – the signal disappeared entirely. With no apparent emissions in any other part of the electromagnetic spectrum, ASKAP J173608.2−321635 is a radio ghost that seems to defy explanation. Prior surveys have detected low-mass stars that periodically flare up with radio energy, but those flaring stars typically have X-ray counterparts. That makes a stellar source unlikely here.