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SPACE.com staff
SPACE.com Space.com Staff
space.com . Tue Nov 3, 9:19 am ET
A gigantic, previously unknown set of galaxies has been found in the distant
universe, shedding light on the underlying skeleton of the cosmos.
"Matter is not distributed uniformly in the universe," said Masayuki Tanaka, an
astronomer with the European Southern Observatory (ESO) who helped discover the
galactic assemblage. "In our cosmic vicinity, stars form in galaxies and
galaxies usually form groups and clusters of galaxies."
But those collections of matter are just small potatoes compared to larger
structures long-theorized to exist.
"The most widely accepted cosmological theories predict that matter also clumps
on a larger scale in the so-called 'cosmic web,' in which galaxies, embedded in
filaments stretching between voids, create a gigantic wispy structure," Tanaka
said.
These filaments are millions of light-years long and constitute the skeleton of
the universe: Galaxies gather around them, and immense galaxy clusters form at
their intersections, lurking like giant spiders waiting for more matter to
digest.
Scientists have struggled, though, to explain how the filaments come into
existence. While massive filamentary structures have often been observed at
relatively small distances from us, solid proof of their existence in the more
distant universe has been lacking until now.
The team led by Tanaka discovered a large structure around a distant cluster of
galaxies in images they had taken earlier. They have now used two major
ground-based telescopes to study this structure in greater detail, measuring
the distances from Earth to more than 150 galaxies, and, hence, obtaining a
three-dimensional view of the structure.
The spectroscopic observations, detailed in the Astronomy & Astrophysics
Journal, were performed using the VIMOS instrument on ESO's Very Large
Telescope in Chile and FOCAS on the Subaru Telescope in Hawaii, operated by the
National Astronomical Observatory of Japan.
With these observations, the astronomers identified several groups of galaxies
surrounding the main galaxy cluster.
The researchers were able to distinguish tens of such clumps, each typically
ten times as massive as our own Milky Way galaxy . and some as much as a
thousand times more massive . while they estimate that the mass of the cluster
amounts to at least ten thousand times the mass of the Milky Way.
Some of the clumps are feeling the fatal gravitational pull of the cluster, and
will eventually fall into it, the data suggested.
This information will allow scientists to explore how galaxies were affected by
their environment at a time when the universe was much younger.
The filament is located about 6.7 billion light-years away from us and extends
over at least 60 million light-years. The newly uncovered structure does
probably extend farther, beyond the field probed by the team, and hence future
observations have already been planned to obtain a definite measurement of its
size.