A signal has been detected recently in the Milky Way and it has raised intrigue among the researchers. The signal was first sensed in April 2019 by the Australian Square Kilometre Array Pathfinder (ASKAP) Variables and Slow Transients (VAST) survey.
However, the new signals do not resemble the old ones. Designated ASKAP J173608.2-321635 and coming from the direction of the galactic center, the signal goes on and off at seemingly random intervals. ASKAP detected it 17 times in under two years.
“The strangest property of this source is that it is highly polarized,” Ziteng Wang, lead author of the study, tells New Atlas. “Our eye cannot distinguish between circularly polarized light and unpolarized light, but ASKAP has the equivalent of polarized sunglasses to filter it out. These kinds of sources are really rare, usually, we only find 10 out of thousands of sources polarized in one observation.”
“Adding to the mystery, the source of the radio signals turns on and off irregularly. The brightness of this source can change dramatically, declining in a single day, but sometimes it can last for a few weeks.”
The source for the signals was being found out but no fruit was borne. The MeerKAT was also found in South Africa that made weekly observations and on February 7, 2021, it returned. It was also sensed in April using the Australia Telescope Compact Array (ATCA).
the team checked archival data of radio surveys, like the Very Large Array (VLA) and ATCA, and others, but there was no record of it prior to April 2019. Wang tells us, this source’s radio signal is too bright to be stellar flares, and they would be visible in infrared as well.
It is also speculated to be a pulsar? These dense objects are created after a massive star collapses, and their fast spinning sends jets of electromagnetic signals over Earth. However, pulsars seem to flash on a predictable timeframe of seconds or milliseconds. Unlike this, the new signal is random and can stay “on” for weeks at a time.
The signal can be from Galactic Center Radio Transients (GCRTs). These are short-lived flashing radio signals that originate from near the center of the Milky Way. However, this is not definite.
“GCRTs are still a mystery,” Wang tells us. “They turn on and off irregularly, they are highly polarized, and there is nothing in X-ray or optical. As the source is close to the Galactic Center, this source could be a new GCRT. However, the timescale of the burst from our source is not consistent with that for GCRTs. [And] they are discovered in lower frequencies. But we don’t even know if all GCRTs share a common origin, it is hard to say.”
It is being speculated that the signal might be from an entirely new source. With time, the researchers are hoping to find the source.
The research is published in Astrophysical Journal.