NASA Telescopes Help Identify Most Distant Galaxy Cluster
WASHINGTON -- Astronomers have uncovered a burgeoning galactic
metropolis, the most distant known in the early universe. This
ancient collection of galaxies presumably grew into a modern galaxy
cluster similar to the massive ones seen today.
The developing cluster, named COSMOS-AzTEC3, was discovered and
characterized by multi-wavelength telescopes, including NASA's
Spitzer, Chandra and Hubble space telescopes, and the ground-based
W.M. Keck Observatory and Japan's Subaru Telescope.
"This exciting discovery showcases the exceptional science made
possible through collaboration among NASA projects and our
international partners," said Jon Morse, NASA's Astrophysics Division
director at NASA Headquarters in Washington.
Scientists refer to this growing lump of galaxies as a proto-cluster.
COSMOS-AzTEC3 is the most distant massive proto-cluster known, and
also one of the youngest, because it is being seen when the universe
itself was young. The cluster is roughly 12.6 billion light-years
away from Earth. Our universe is estimated to be 13.7 billion years
old. Previously, more mature versions of these clusters had been
spotted at 10 billion light-years away.
The astronomers also found that this cluster is buzzing with extreme
bursts of star formation and one enormous feeding black hole.
"We think the starbursts and black holes are the seeds of the
cluster," said Peter Capak of NASA's Spitzer Science Center at the
California Institute of Technology in Pasadena. "These seeds will
eventually grow into a giant, central galaxy that will dominate the
cluster -- a trait found in modern-day galaxy clusters." Capak is
first author of a paper appearing in the Jan. 13 issue of the journal Nature.
Most galaxies in our universe are bound together into clusters that
dot the cosmic landscape like urban sprawls, usually centered around
one old, monstrous galaxy containing a massive black hole.
Astronomers thought that primitive versions of these clusters, still
forming and clumping together, should exist in the early universe.
But locating one proved difficult -- until now.
Capak and his colleagues first used the Chandra X-ray Observatory and
the United Kingdom's James Clerk Maxwell Telescope on Mauna Kea,
Hawaii, to search for the black holes and bursts of star formation
needed to form the massive galaxies at the centers of modern galaxy
cities. The astronomers then used Hubble and the Subaru telescopes to
estimate the distances to these objects, and look for higher
densities of galaxies around them. Finally, the Keck telescope was
used to confirm that these galaxies were at the same distance and
part of the same galactic sprawl.
Once the scientists found this lumping of galaxies, they measured the
combined mass with the help of Spitzer. At this distance the optical
light from stars is shifted, or stretched, to infrared wavelengths
that can only be observed in outer space by Spitzer. The lump sum of
the mass turned out to be a minimum of 400 billion suns -- enough to
indicate that the astronomers had indeed uncovered a massive proto-cluster.
The Spitzer observations also helped confirm a massive galaxy at the
center of the cluster was forming stars at an impressive rate.
Chandra X-ray observations were used to find and characterize the
whopping black hole with a mass of more than 30 million suns. Massive
black holes are common in present-day galaxy clusters, but this is
the first time a feeding black hole of this heft has been linked to a
cluster that is so young.
Finally, the Institut de Radioastronomie Millimétrique's
interferometer telescope in France and 30-meter telescope in Spain,
along with the National Radio Astronomy Observatory's Very Large
Array telescope in New Mexico, measured the amount of gas, or fuel
for future star formation, in the cluster. The results indicate the
cluster will keep growing into a modern city of galaxies.
"It really did take a village of telescopes to nail this cluster,"
said Capak. "Observations across the electromagnetic spectrum, from
X-ray to millimeter wavelengths, were all critical in providing a
comprehensive view of the cluster's many facets."
COSMOS-AzTEC3, located in the constellation Sextans, is named after
the region where it was found, called COSMOS after the Cosmic
Evolution Survey. AzTEC is the name of the camera used on the James
Clerk Maxwell Telescope -- this camera is now on its way to the Large
Millimeter Telescope located in Mexico's Puebla state.
For more information about NASA's Spitzer, Chandra and Hubble space
telescopes, visit:
http://www.nasa.gov/spitzer
http://www.nasa.gov/chandra
http://www.nasa.gov/hubble
Source: NASA
