Astronomers map action in the cosmic suburbs (Forwarded)

Institute for Astronomy
University of Hawai'i
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CONTACT:
Dr. Roy Gal (808) 956-6317 or Mrs. Karen Rehbock (808) 956-6829

FOR RELEASE: 9:20 a.m. Hawaiian Standard Time, May 28, 2007

ASTRONOMERS MAP ACTION IN THE COSMIC SUBURBS

A group of Hawaii and California astronomers led by Dr. Roy Gal of the
University of Hawaii at Manoa and Dr. Lori Lubin of the University of
California at Davis is announcing today at the American Astronomical
Society meeting in Honolulu, Hawaii, that they have, for the first time,
mapped where the "action" is in a mega-structure in the distant universe.

Large galaxy clusters are typically considered the universe's
metropolises, and for years many astronomers have focused their attention
"downtown." However, this research shows that all the action is actually
happening in the galactic suburbs.

"The most interesting thing that we've found so far is the incredible
amount of activity occurring in galactic suburbia," says Lubin, who is the
principal investigator of the Observations of Redshift Evolution in Large
Scale Environments (ORELSE) Survey. "We see unusually large numbers of
galaxies with high star formation rates, producing over 100 new suns per
year, and with active central supermassive black holes."

ORELSE is one of the first comprehensive surveys of large-scale
environments around very massive galaxy clusters between 6 and 9 billion
light-years away. In this study, Lubin and her collaborators hope to gain
insights into physical properties that affect galaxies in the cluster
outskirts and understand the interactions that leave them forever changed.

Like grapes, the universe's galaxies come in clusters, and those clusters
typically bunch together to form even more massive structures, or
superclusters. Scientists refer to the large clusters at the heart of a
supercluster as the Los Angeleses, New Yorks or Londons. Much like
freeways connect big cities to smaller towns, a web of galaxies connects
these large clusters to smaller groups of galaxies.

In the past, telescope limitations forced astronomers to focus their
studies on either the centers of large clusters or random regions in the
cosmic web. Now, with the latest ground-based and space-based telescopes,
scientists are able to map larger areas. "Our research is like mapping the
whole Big Island of Hawaii instead of just the town Hilo," says Gal, who
is a co-investigator of the study. "We have already discovered the largest
known supercluster -- cluster of clusters -- present when the universe was
half its current age."

To see what is happening in the cluster suburbs, the team collected data
with nine different telescopes, including the 10-meter Keck I and II
telescopes, the 8-meter Subaru telescope and the 4-meter United Kingdom
Infrared Telescope on Mauna Kea, Hawaii; the 5-meter Palomar telescope in
California; the 4-meter Kitt Peak telescope in Arizona; and the Very Large
Array in New Mexico. For space-based observations, the team used three of
NASA's Great Observatories: the Spitzer and Hubble space telescopes, and
the Chandra X-ray Observatory.

"The Spitzer observations interest me. With Spitzer, we expect to discover
even more galaxies containing voracious black holes. They may be hidden
behind thick curtains of dust, but Spitzer will find them," says Dr.
Gordon Squires, of the Spitzer Science Center, Pasadena, CA, another
co-investigator.

Team members also note that this study may provide valuable clues about
our Milky Way galaxy's future. They say that our Milky Way is currently
sitting in galactic suburbia and that our nearest cosmic metropolis is the
Virgo Cluster of galaxies, located approximately 100 million light-years
away.

The collaboration also includes Dr. Mark Lacy and Dr. Jason Surace at the
Spitzer Science Center, Dr. Neal Miller at Johns Hopkins University,
Baltimore, and Dr. Christopher Fassnacht, Dr. Dale Kocevski, and graduate
student Brian Lemaux at the University of California, Davis. Surace (1998)
and Kocevski (2006) received their doctorates from UH Manoa.

The title of the paper being given at the AAS meeting is "A Complex
Supercluster at z = 0.9: Multiwavelength Observations of Cl1604," by Roy
R. Gal, L. M. Lubin, G. K. Squires, B. Lemaux, D. Kocevski, N. Miller, and
C. Fassnacht.

The Institute for Astronomy at the University of Hawaii conducts research
into galaxies, cosmology, stars, planets, and the sun. Its faculty and
staff are also involved in astronomy education, deep space missions, and
in the development and management of the observatories on Haleakala and
Mauna Kea.

Established in 1907 and fully accredited by the Western Association of
Schools and Colleges, the University of Hawaii is the state's sole public
system of higher education. The UH System provides an array of
undergraduate, graduate, and professional degrees and community programs
on 10 campuses and through educational, training, and research centers
across the state. UH enrolls more than 50,000 students from Hawaii, the
U.S. mainland, and around the world.

IMAGE CAPTION:
[http://www.ifa.hawaii.edu/info/press-releases/AAS/rgal_aas07-630.jpg
(427KB)]
Multiple views of a supercluster seen when the universe was half its
present age show a diversity of structure. Large clusters (cities),
consisting mainly of red galaxies, are connected by filaments and smaller
groups (highways and suburbs) with a higher fraction of younger, blue
galaxies. Galaxies with supermassive black holes. shown in yellow, tend to
avoid the cluster centers, while many radio sources (green) are clustered
similar to normal galaxies. The inset shows a Hubble Space Telescope image
of one of the clusters, with confirmed members circled.


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