A team of Italian astronomers scanning the universe for potential discoveries has come across a mysterious and unidentified group of radio signals.
When we think of radio signals being received from outer space, we might jump to the conclusion that they are communications from extra-terrestrials.
In reality, the Earth is bombarded by varying radio signals on a daily basis across multiple spectrums, including gamma ray, X-ray and ultraviolet.
However, a recent recording of a group of radio signals have left a team of Italian astronomers mystified as to what they are and what their origin is.
Using NASA’s Swift space observatory, the Institute of Space Astrophysics and Cosmic Physics of Palermo team, led by Andrea Maselli, observed 21 signals included in the Third Cambridge Catalogue (3CR) of radio sources.
The 3CR is one of the most comprehensive sources of radio signals detected, which could advance our knowledge about the nature and evolution of powerful radio galaxies and quasars.
The only problem is that these 21 radio sources found in 3CR as part of a previous NRAO VLA Sky Survey (NVSS) have never been observed in X-rays.
‘Obscured active galaxies’
Not only that, but they are completely unidentified, with no assigned optical or infrared counterpart.
In this latest research, each one of the mysterious sources were observed by two telescopes on board Swift, including the X-ray Telescope (XRT) and the Ultraviolet/Optical Telescope (UVOT).
Of the 21 sources investigated, the researchers found that nine exhibit significant emission in the soft X-ray band.
The real mystery for the research team, however, is that no optical/UV counterpart has been found by UVOT.
This leads to the assumption that these unidentified radio sources should be classified as obscured active galaxies.
The team has admitted that it is still too early to call what the sources might be, as spectroscopic observations will need to be done to form a conclusion.
The team’s research has now been published online at arXiv.org.