File this one under "likely not aliens, but you never know."
A team of Australian astronomers discovered a mysterious radio signal of unknown origin, saying it requires further investigation to determine its source.
The bright and compact radio signal, given the designation J054149.24–641813.7, was discovered by a team led by Joel Balzan of Western Sydney University in Australia, a press statement reveals.
Radio sources are generally emitted by pulsars, nebulae, quasars, and radio galaxies, though some radio sources over the years have been anomalous and unattributed, leading to theories that they might come from intelligent extraterrestrial civilizations.
One of the leading examples is the Wow! Signal, which was recently the focus of an investigation by amateur astronomer Alberto Caballero, who believes he may have pinpointed its source at a Sun-like star 1,800 lightyears from Earth.
The Western Sydney University researchers, who outlined their findings in a paper published in pre-print server arXiv, haven't suggested aliens are the source of J054149.24–641813.7. However, they did eliminate some common radio sources from contention and said more observations are needed to help uncover the mysterious signal's origins.
A cosmic outlier 60 million lightyears from Earth
The team discovered the radio source while observing galaxy NGC 2082 using Australian Square Kilometer Array Pathfinder (ASKAP), Australia Telescope Compact Array (ATCA), and the Parkes radio telescope. They identified a strong point radio source 20 arcseconds from the center of the galaxy. NGC 2082 is located approximately 60 million lightyears from Earth.
In their paper, the scientists revealed that the radio luminosity of J054149.24–641813.7 at 888 MHz is at a level of 129 EW/Hz and has a flat radio spectral index (about 0.02). This, they explained, means the radio source is likely not a supernova remnant (SNR) or a pulsar and suggests it may be of thermal origin.
They also highlighted the compact nature of the radio source and its location relative to its galaxy, stating that it drew comparisons to some fast radio bursts (FRBs).
The most likely possibility, the researchers explained, is that J054149.24–641813.7 is an extragalactic background source, such as a quasi-stellar object (QSO, quasar), radio galaxy, or active galactic nucleus (AGN). More data is needed, however, to confirm their hypothesis.