Published 14:55 IST, July 10th 2020
Mysterious circular objects spotted orbiting Milky Way's supermassive black hole, see pics
Mysterious circular object unlike any class of astronomical object orbiting the Milky Way's supermassive black hole Sagittarius A* detected on Array Pathfinder.
Astronomers have discovered four new and mysterious objects at radio wavelengths, circular and so much brighter on edge, unlike any class of astronomical object orbiting the Milky Way's supermassive black hole, Sagittarius A*. In a new paper published in journal Nature Astronomy, the Australian Square Kilometre Array Pathfinder detected strange dust-shrouded objects looking like a ring, a bubble, or an island in the deep space which scientists termed as ORCs - short for "Odd Radio Circles".
Compact like stars as they run laps around our galaxy's gargantuan black hole, the international team of astronomers led by astrophysicist Ray Norris of Western Sydney University in Australia discovered the objects and released information in arXiv research paper. "Circular features are well-known in radio astronomical images, and usually represent a spherical object such as a supernova remnant, a planetary nebula, a circumstellar shell, or a face-on disc such as a protoplanetary disc or a star-forming galaxy," wrote the researchers. The mysterious ORCs were first spotted in data collected during the late 2019 Pilot Survey of the Evolutionary Map of the Universe (EMU) conducted using one of the world's most sensitive radio telescope arrays.
While inspecting the collective images, the scientists discovered strange circles that they suspected at first could be a glitch. However, when the fourth ORC was discovered by researchers in archival data, collected in 2013 with the Giant MetreWave Radio Telescope, the object was revealed. Further, a follow-up observation of ORC 1 and ORC 2 using a different telescope was done which confirmed the four ORCs are at high galactic latitudes. Around 1 arcminute in diameter, scientists studied images on Australia Telescope Compact Array further noting that the objects sat at some distance from the galactic plane. Further, it was found that the objects were invisible in X-ray, optical, or infrared wavelengths and were strangely only detectable in radio wavelengths.
There could also be more than one cause of the ORCs. It really is an intriguing mystery, the scientists wrote in research arXiv.
Transients taken place in "distant past"
In the paper, the researchers concluded that whatever was causing the ORCs was likely outside the Milky Way galaxy. They noted that the objects could be a result of some spherical shockwave from a massive galactical event. Scientists explained, “Several such classes of transient events, capable of producing a spherical shock wave, have recently been discovered, such as fast radio bursts, gamma-ray bursts, and neutron star mergers. However, because of the large angular size of the ORCs, any such transients would have taken place in the distant past.” While scientists noted that the ORCs could represent a new category of a known phenomenon, such as the jets of a radio galaxy or blazar, it was also possible that the objects were some remnant of a previous outflow from a radio galaxy.
(All Images Credit: UCLA/NASA)
Updated 14:55 IST, July 10th 2020