At the end of last year, researchers using Nasa’s Swift space observatory launched an investigation to study a group of mysterious radio sources first detected nearly six decades ago.

For four months, team observed 21 bright radio sources from the revised Third Cambridge Catalogue, leading to the detection of ‘significant’ emissions for nine of them with the X-ray Telescope.

But, when using the spacecraft’s Ultraviolet/Optical Telescope, no sources could be found.

These new observations support earlier assumptions that the source of these emissions may be ‘heavily obscured’ active galaxies.

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