Scientists investigate unidentified radio sources


#Science #ScientistsScientists investigate unidentified radio sources : A team of researchers led by Andrea Maselli of the Institute of Space Astrophysics and Cosmic Physics of Palermo, Italy, has conducted an observational campaign of a group of unassociated radio sources with NASA’s Swift space observatory.

The observations were aimed at revealing the true nature of these so far unidentified sources. The results were published Sept. 23 in a paper on

The Swift spacecraft, scanning the universe in the gamma-ray, X-ray, ultraviolet, and optical wavebands, is an invaluable tool when it comes to studying gamma-ray bursts and other electromagnetic events. It has already proved its scientific importance in many ways, for example by performing the first sensitive hard X-ray survey of the sky.

Recently, Maselli and his team employed Swift to observe 21 bright radio sources included in the revised Third Cambridge Catalogue (3CR) of radio sources. The catalog contains celestial radio sources detected at 178 MHz that could advance our knowledge about the nature and evolution of powerful radio galaxies and quasars.

However, some sources described in the 3CR catalog, including these detected by the NRAO VLA Sky Survey (NVSS), are not only unobserved in X-rays, but are, in fact, completely unidentified, lacking an assigned optical or infrared counterpart.

The authors of the paper decided to fill this gap by conducting a supplementary optical-to-X-ray campaign with the Swift spacecraft, in order to better characterize the properties of these unidentified sources.

“We have investigated a group of unassociated radio sources included in the 3CR catalog to increase the multi-frequency information on them and possibly obtain an identification,” the researchers wrote in the paper.

Each of the 21 sources was observed by two telescopes onboard Swift – the X-ray Telescope (XRT) and the Ultraviolet/Optical Telescope (UVOT). The observation campaign lasted from November 2014 to March 2015.