Brilliant beacon is a quasar too far
Light from early universe strains black hole formation theories
By Nadia Drake
Astronomers peering at the early universe have glimpsed the most distant
quasar yet. Powered by a black hole
of 2 billion solar masses, the quasar
appears as it did 12.9 billion years ago,
when the universe as humans know it
was just beginning to emerge from the
Big Bang.
The supermassive black hole is pulling enormous clumps of matter into its
gravitational clutches. As a result, the
quasar emits 60 trillion times as much
light as the sun, an international team
reports in the June 30 Nature.
The team identified the object from
the U.K. Infrared Telescope’s Infrared
Deep Sky Survey, which probes 5 percent
of the sky. Daniel Mortlock of Imperial
College London, an author of the study,
likens the process to panning for gold.
“You see many shiny things in the infra-
red, but not all of them are nuggets,” he
says. “We got a big nugget this time.”
Already, the uncharismatically named
ULAS J1120+0641 has posed both clues
and puzzles about the early universe.
The most distant known quasar emits
60 trillion times the light of the sun.
This illustration shows the quasar enveloped in a reddish bubble produced when
its energy cleaves hydrogen atoms.
“The surprising thing is that this
object is right at the farthest possible
distance we could see,” Mortlock says.
The object is so distant that, because
of the time it took the quasar’s light to
reach Earth, astronomers are seeing
it as it appeared just 770 million years
after the Big Bang. While theorists had
predicted quasars could form that soon
after the Big Bang, none had anticipated
seeing one so large in the embryonic
universe.
“It is like finding a 6-foot-tall child
in kindergarten,” says astrophysicist
Marta Volonteri of the University of
Michigan in Ann Arbor.
Prevailing theories suggest that black
holes form either from the tiny, dense
objects left behind after the explosive
deaths of massive stars or from the
direct collapse of cosmic gases. For the
first theory to be correct, Volonteri says,
ULAS J1120+0641 would have needed
to begin growing before the Big Bang,
suggesting that the direct collapse
theory is better supported by the
quasar’s discovery.
Scientists think there are maybe 100
distant, bright objects like the newly
discovered quasar sprinkled throughout the entire sky, and astrophysicist
Avi Loeb of Harvard University says he
hopes sky surveys will find more of them.
These quasars, if they exist, could act as
beacons of light to help guide astronomers studying the early universe.
The next steps include finding more of
these giants in the early cosmic playground and studying the quasar’s neighborhood using different wavelengths.
The discovery is intriguing, says Chris
Willott of National Research Council Canada, but he adds some caution:
“This could be one charmed place in the
universe where things are going on very
quickly. It’s always dangerous if you base
everything you know on one object.” s
Orbiter delivers
sharp moon map
After orbiting the moon for two years,
NASA’s Lunar Reconnaissance Orbiter has
beamed back more than 192 terabytes
of data, scientists reported June 21.
Those data include 4 billion measurements made by the orbiter’s laser
altimeter, which allowed scientists
to construct an elevation map of the
moon’s pockmarked surface. The spacecraft’s data show the lunar surface in
far sharper resolution (bottom image)
compared with maps made in 2005
by the U.S. Geological Survey’s Uni;ed
Lunar Control Network (top). Flying about
50 kilometers above the cratered world,
the 1,900-kilogram orbiter gathered data
on the moon’s temperature, composition
and elusive far side, helping scientists
identify shaded spots likely to hold frozen water and sunnier spots that could
one day host a solar-powered moon
base. — Nadia Drake
TOP IMAGES: GODDARD SPACE FLIGHT CENTER SCIENCE VISUALIZATION STUDIO/NASA; LEFT: GEMINI OBSERVATORY
www.sciencenews.org
