A team of researchers headed by Andrea Mazelli from the Institute of space astrophysics and cosmic physics of Palermo, Italy, conducted a campaign observation of a group of radio sources, not associated with known sources in other bands of the electromagnetic spectrum, using a space Observatory of NASA “swift”. These observations were aimed at identifying the true nature of these is still not identified by scientists sources.
Recently Mazelli and his team via satellite swift observed bright radio source 21 included in an updated Third Cambridge catalogue of radio sources (Third Cambridge Catalogue, 3CR). This directory contains the radio sources discovered at a frequency of 178 MHz, the study of which could deepen our knowledge about the nature and evolution of an intensively emitting radio galaxies and quasars.
However, some of the sources described in the 3CR catalog including the sources detected with the help of sky survey NRAO VLA Sky Survey (NVSS), not only have never been observed in x-ray range, but, in fact, still remained not completely identified, that is not matched with their corresponding sources in the optical or infrared ranges.
In this new study, conducted by a team of Mazelli, each of the 21 studied sources were observed with two telescopes on Board the satellite swift x – ray telescope and an optical/UV telescope.
According to this study, of the 21 investigated sources nine sources show very intense emission in soft x-rays. Scientists have been able to appropriate these nine sources IR-sources in the directory, compiled with the help of the AllWISE sky survey (All Wide-field Infrared Survey Explorer), in addition, a similar compliance with the IR sources in this directory was established for the four sources of the studied pool, not emitting in the soft x-rays.
The results of this study to some extent surprised the authors, since none of the studied radio sources is not matched in the optical/UV bands. According to the working hypothesis put forward by the team Mazelli, it may be due to the fact that these unidentified sources are active galaxies, shrouded in dense clouds of dust, but to check this assumption requires additional spectroscopic observations.