A growing black hole, called a quasar, can be seen at the center of a
faraway galaxy in this artist's concept. Astronomers using NASA's Spitzer
and Chandra space telescopes discovered swarms of similar quasars hiding
in dusty galaxies in the distant universe.
The quasar is the orange object at the center of the large,
irregular-shaped galaxy. It consists of a dusty, doughnut-shaped cloud of
gas and dust that feeds a central supermassive black hole. As the black
hole feeds, the gas and dust heat up and spray out X-rays, as illustrated
by the white rays. Beyond the quasar, stars can be seen forming in clumps
throughout the galaxy. Other similar galaxies hosting quasars are visible
in the background.
The newfound quasars belong to a long-lost population that had been
theorized to be buried inside dusty, distant galaxies, but were never
actually seen. While some quasars are easy to detect because they are
oriented in such a way that their X-rays point toward Earth, others are
oriented with their surrounding doughnut-clouds blocking the X-rays from
our point of view. In addition, dust and gas in the galaxy itself can
block the X-rays.
Astronomers had observed the most energetic of this dusty, or obscured,
bunch before, but the "masses," or more typical members of the population,
remained missing. Using data from Spitzer and Chandra, the scientists
uncovered many of these lost quasars in the bellies of massive galaxies
between 9 and 11 billion light-years away. Because the galaxies were also
busy making stars, the scientists now believe most massive galaxies spent
their adolescence building up their stars and black holes simultaneously.
The Spitzer observations were made as part of the Great Observatories
Origins Deep Survey program, which aims to image the faintest distant
galaxies using a variety of wavelengths.
