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Last updated on April 20, 2014 at 14:04 EDT

Our Universe: Dark and Messy

January 7, 2008

Our
universe is a mess — a colossal “cosmic web” of galaxies strung into
filaments and tendrils that are millions or billions of light-years long.

Although
this web’s basic structure is resolved, astronomers say understanding it in
more detail requires new observatories, better computing and a lot of luck.

“When
you look into a large telescope, the reality of the
cosmic web
hits you in the face because you can see how galaxies are
organized,” said Rodrigo Ibata, an astronomer at the Observatoire Astronomique
de Strasbourg in France. “We have clear evidence for the cosmic web’s
existence, but there is still so much we don’t know about it.”

Ibata
explained that the cosmic web filaments are held together by
dark matter, unseen stuff that makes up 85 percent of all mass in the
universe.

“It’s
intrinsically tough to study something you can’t see, so dark matter makes
understanding the cosmic web an exceedingly difficult challenge,” Ibata
told SPACE.com.

Ibata and
other astronomers detail some of the cosmic web’s mysteries last week in the
journal Science.

Intergalactic
highway

The cosmic
web is thought to funnel galaxies, gas and
dark matter
around the universe, something like a chaotic intergalactic
highway. Ibata said he’s looking to our own celestial neighborhood for effects
of this network.

“We
think cosmic web tendrils feed directly into galaxies, dump matter onto them
and build them up,” Ibata said.

Ibata hopes
new star data gathered by the European Space Agency’s GAIA spacecraft, set to
launch in 2011, will help gather evidence of such activity near the Milky Way.

“It’s
going to make things very interesting over the coming years,” he said of
GAIA, which will finely measure the distances and movements of more than a
billion local stars. Such data could reveal where — and what — cosmic web
tendrils might be spilling into our neck of the celestial woods.

“The
environment within these tendrils could be one of the most important factors in
galaxy formation,” Ibata said.

To use mountains
of data
that GAIA and other observatories are expected to deliver in the
future, however, Ibata said computer technology will have to catch up. “If
we were to get such data now, we wouldn’t be able to efficiently process
it,” he said.

Simulating
the universe

Claude-Andre
Faucher-Giguere, a graduate student in astrophysics at Harvard University, agrees.

“We
need powerful computers to deal with raw astronomy data,” Faucher-Giguere
said. “But another aspect is that once it’s processed, we need to be able
to learn something from it.”

Faucher-Giguere
said computer simulations help with the task by giving astronomers grounds for
comparison. If a simulation fits a set of observations, it helps astronomers
pick the best theoretical track to explain what they see.

Our current
big-picture view of the universe is based mostly on optical light,
Faucher-Giguere said, but new
observatories
will look deep into the cosmos in wavelengths such as
infrared and radio.

“We’ll
need new, better simulations to make sense of data we haven’t yet learned how
to analyze,” he said. “We need to be prepared or else we won’t know
what we’re looking at.”

Faucher-Giguere
expects astronomers to increasingly team up with computer-savvy theoreticians
to extract the latest knowledge about our universe in an efficient way.

“Astronomy
is driven by new observations,” he said, “but to make use of these
new windows onto the universe, we really have to keep up with the theoretical
work.”


Source: imaginova