As many as one in five of the most energetic objects of the
early universe were black holes—those fascinating deep space vacuum cleaners
whose gravity is so immense that even light can’t escape.
An astronomical team that included University of Hawai`i’s
Guenther Hasinger reported in The Astrophysical Journal that black holes formed
early and often in the young universe.
(Image: Background radiation from when the universe was only a few hundred years old can provide hints of its structure. More detail on hthis image is here. Credits: Illustration by Karen Teramura, UHIfA. Credits for inserted images:
cosmic microwave background (left): NASA WMAP Science Team;
black hole blow up, AGN (center, top): NASA/JPL-Caltech;
first stars blow up (center, bottom): NASA/JPL-Caltech, A. Kashlinsky (GSFC);
Hubble Ultra Deep Field (right): NASA/ESA, S. Beckwith(STScI) and the HUDF Team.)
Hasinger, the Director of the university’s Institute for
Astronomy, was part of a team that compared background infrared and x-ray
signals dating back to the early universe. They used two NASA observatories,
the Chandra X-ray Observatory and Spitzer Space Telescope
"We wanted to understand the nature of the sources in
this era in more detail, so I suggested examining Chandra data to explore the
possibility of X-ray emission associated with the lumpy glow of the CIB (cosmic
infrared background )," Hasinger said. (Hasinger in photo at right. Credit: UH/IfA)
By comparing the results of the x-ray and infrared, they
were able to determine that there were fluctuations in energy that were
consistent in both forms of radiation, and that there was information in those fluctuations.
"This measurement took us some five years to complete
and the results came as a great surprise to us," said Nico Cappelluti, an
astronomer with the National Institute of Astrophysics in Bologna, Italy, and the
University of Maryland, Baltimore County, in Baltimore.
In complex calculations, the scientists removed
from the data the known star and galaxy sources of energy, and were left with a
remainder they could study. And since black holes are particularly intense,
energetic energy sources, the astronomers believed they could identify black
hole signatures in the remnant radiation maps.
"Our results indicate black holes are responsible for
at least 20 percent of the cosmic infrared background, which indicates intense
activity from black holes feeding on gas during the epoch of the first
stars," said Alexander Kashlinsky, an astrophysicist at NASA's Goddard
Space Flight Center in Greenbelt, Maryland.
All of that leads us into a detour into the insane world of
black holes.
The density of the interior of black holes is so immense
that nothing gets out. But like a stealthy beast that only makes a lot of noise
when it’s eating, black holes are detectable because of the big energy
signature of matter being sucked into them.
Around many black holes are accretion disks, where matter is
being sucked toward oblivion. And where this final sucking occurs is called the “event
horizon.” The matter spinning toward the event horizon lights up and sends out
a kind of final radiation distress signal before it is gone. Like a cry of help from someone being drawn into a whirlpool.
Today, there are not nearly as many black hole signatures as there were in the early universe. Hasinger said that many of the universe’s black holes have
gone silent. They have sucked all the matter in their regions of space, so
there’s nothing left to eat—no accretion disks, so no radiation.
“Today only about 1% of all of these black holes are
actively eating and radiating, while in the early universe probably all of them
were active,” Hasinger said.
Today, astronomical research indicates every galaxy has a supermassive black hole at its
center, and the larger galaxies have larger supermassive black holes. Supermassive black holes have masses ranging from a million to several billion solar
masses.
For more information, visit:
http://www.ifa.hawaii.edu/info/press-releases/blackholes2013/
© Jan TenBruggencate 2013
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