This false-color image from NASA’s Spitzer Space Telescope shows a distant galaxy (yellow) that houses a quasar, a super-massive black hole circled by a ring, or torus, of gas and dust.
If you can’t explain why some fatties can’t seem to stop themselves from dumping all kinds of food into their voracious mouth, the mystery is actually universal.
Finally, NASA scientists have seen through the sharp infrared eyes of their Spitzer Space Telescope that most of the biggest black holes in the universe have been chomping cosmic meals of planets, stars and galaxies – just like the incorrigible fatties in our midst.
NASA has announced that it has uncovered what may be the long-sought missing population of hungry black holes known as quasars.
“From past studies using X-rays, we expected there were a lot of hidden quasars, but we couldn’t find them,” said Alejo Martinez-Sansigre of the University of Oxford, England. He is lead author of a paper about the research in this week’s Nature. “We had to wait for Spitzer to find an entire population of these dust-obscured objects.”
Quasars are super-massive black holes that are circled by a giant ring of gas and dust. They live at the heart of distant galaxies and can consume up to the equivalent mass of one thousand stars in a single year. As their black holes suck in material from their dusty rings, the material lights up brilliantly, making quasars the brightest objects in the universe. This bright light comes in many forms, including X-rays, visible and infrared light.
Astronomers have puzzled for years over the question of how many of these cosmic behemoths are out there.
This week, the Spitzer telescope found hundreds of “missing” black holes or quasars lurking in dusty galaxies billions of light-years away. Researchers found 21 examples of these quasars in a small patch of sky.
“If you extrapolate our 21 quasars out to the rest of the sky, you get a whole lot of quasars,” said Dr. Mark Lacy of the Spitzer Science Center, California Institute of Technology, Pasadena, Calif., a co-author of the Nature paper. “This means that, as suspected, most super-massive black hole growth is hidden by dust.”
The discovery will allow astronomers to put together a more complete picture of how and where quasars form in our universe. Of the 21 quasars uncovered by Spitzer, 10 are believed to be inside fairly mature, giant, elliptical galaxies. The rest are thought to be encased in thick, dusty galaxies that are still forming stars.
“Active, supermassive black holes were everywhere in the early universe,” said study team member Mark Dickinson of the National Optical Astronomy Observatory in Tuscon, Ariz. “We had seen the tip of the iceberg before in our search for these objects. Now, we can see the iceberg itself.”
The finding, detailed in two studies published in the Nov. 10 issue of Astrophysical Journal, is the first direct evidence that most, if not all, massive galaxies in the distant universe spent their youths constructing supermassive black holes at their cores.
It could also help answer fundamental questions about how massive galaxies such as our Milky Way evolved.
Using NASA’s Chandra X-ray and Spitzer Space Telescopes, the team detected unusually high levels of infrared light emitted by 200 galaxies in the distant universe. They think the infrared light was created by material falling into “quasars”—supermassive black holes surrounded by doughnut-shaped clouds of gas and dust—at the center of the galaxies.
The new quasar-containing galaxies are all about the same mass as our Milky Way, but are irregular in shape. They are located 9 billion to 11 billion light-years away and existed at a time when the universe was in its adolescence and between 2.5 and 4.5 billion years old.
For decades, scientists have predicted that a large population of quasars should be found at those distances but had only spotted a few of them.
The newfound quasars confirm what scientists have suspected for years now: that supermassive black holes play a major role in star formation in massive galaxies. The observations suggest massive galaxies steadily build up their stars and black holes simultaneously until they get too big and the black holes suppress star formation.
The new quasars also suggest that collisions between galaxies might not be as important for galaxy evolution as once thought. “Theorists thought mergers between galaxies were required to initiate this quasar activity, but now we see that quasars can be active in unharassed galaxies,” said study team member David Alexander of Durham University in the UK.
All these supermassive black holes or quasars may just be too big for our Earth-bound brains to comprehend. Well, at least when you see fatties roaming around the mall, you’ll get an idea of how the universe is getting pretty crowded.