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| Figure 1 | Poster Version |
A long-lost population of active supermassive black holes, or quasars, has
been uncovered by NASA's Spitzer and Chandra space telescopes. This image,
taken with Spitzer's infrared vision, shows a fraction of these black
holes, which are located deep in the bellies of distant, massive galaxies
(circled in blue).
Spitzer originally scanned the field of galaxies shown in the picture as
part of a multiwavelength program called the Great Observatories Origins
Deep Survey, or Goods. This picture shows a portion of the Goods field
called Goods-South. When astronomers saw the Spitzer data, they were
surprised to find that hundreds of the galaxies between 9 and 11 billion
light-years away were shining with an unexpected excess of infrared light.
They then followed up with X-ray data from Chandra of the same field, and
applied a technique called stacking, which adds up the faint light of
multiple galaxies. The results revealed that the infrared-bright galaxies
are hiding many black holes that had been theorized about before but never
seen. This excess infrared light is being produced by the growing black
holes.
The other smudges in this picture are distant galaxies, most of which are
closer to us than the circled galaxies, causing them to appear brighter.
This image was taken by Spitzer's multiband imaging photometer at a
wavelength of 24 microns. It shows the faintest distant objects ever
observed with Spitzer at this wavelength.
