The combined power of NASA's Great Observatories - the Hubble Space Telescope, the Chandra X-ray Observatory, and the Spitzer Space Telescope - have been combined to find a hidden population of supermassive black holes in the universe. It took the penetrating view of Spitzer to finally uncover the black holes and their surrounding galaxies.
All these space telescopes peered across 13 billion light-years of space into a small region of dark sky (called the Great Observatories Origins Deep Survey field, or the GOODS field for short) that contains many thousands of galaxies.
Comparing visible light and X-ray views of this region, astronomers pinpointed X-ray sources that are supermassive black holes in young galaxies which largely existed when the universe was half its present age. But the telltale X-ray glow from other sources didn't have any obvious host galaxies until Spitzer uncovered them. In this view the X-ray data is colored blue and the Spitzer images are colored red.
[Top and Bottom Left] - A Hubble Space Telescope deep view of two small portions of the GOODS field uncovers some of the faintest galaxies ever seen. But at the center of each image is the X-ray glow from heated material falling into a million- or billion-solar mass black hole - as seen by Chandra - which does not have any visible-light counterpart in either field.
[Top and Bottom Right] - The Spitzer Space Telescope's infrared view of the same two regions of the GOODS field uncovers the glow of a powerful active galactic nucleus in both views. The nucleus is either shrouded in dust, or is at such a great distance that all of its light has been stretched into infrared wavelengths by the universe's expansion.