Herschel Sees Intergalactic Bridge Aglow With Stars

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE 818-354-5011
http://www.jpl.nasa.gov

Written by Adam Hadhazy
Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin@jpl.nasa.gov

News feature: 2012-139 May 19, 2012

Herschel Sees Intergalactic Bridge Aglow With Stars

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2012-139&cid=release_2012-139

The Herschel Space Observatory has discovered a giant, galaxy-packed filament ablaze with
billions of new stars. The filament connects two clusters of galaxies that, along with a third
cluster, will smash together and give rise to one of the largest galaxy superclusters in the
universe.

Herschel is a European Space Agency mission with important NASA contributions.

The filament is the first structure of its kind spied in a critical era of cosmic buildup when
colossal collections of galaxies called superclusters began to take shape. The glowing galactic
bridge offers astronomers a unique opportunity to explore how galaxies evolve and merge to
form superclusters.

"We are excited about this filament, because we think the intense star formation we see in its
galaxies is related to the consolidation of the surrounding supercluster," says Kristen Coppin, an
astrophysicist at McGill University in Canada, and lead author of a new paper in Astrophysical
Journal Letters.

"This luminous bridge of star formation gives us a snapshot of how the evolution of cosmic
structure on very large scales affects the evolution of the individual galaxies trapped within it,"
says Jim Geach, a co-author who is also based at McGill.

The intergalactic filament, containing hundreds of galaxies, spans 8 million light-years and links
two of the three clusters that make up a supercluster known as RCS2319. This emerging
supercluster is an exceptionally rare, distant object whose light has taken more than seven billion
years to reach us.

RCS2319 is the subject of a huge observational study, led by Tracy Webb and her group at
McGill. Previous observations in visible and X-ray light had found the cluster cores and hinted at
the presence of a filament. It was not until astronomers trained Herschel on the region, however,
that the intense star-forming activity in the filament became clear. Dust obscures much of the
star-formation activity in the early universe, but telescopes like Herschel can detect the infrared
glow of this dust as it is heated by nascent stars.

The amount of infrared light suggests that the galaxies in the filament are cranking out the
equivalent of about 1,000 solar masses (the mass of our sun) of new stars per year. For
comparison's sake, our Milky Way galaxy is producing about one solar-mass worth of new stars
per year.

Researchers chalk up the blistering pace of star formation in the filament to the fact that galaxies
within it are being crunched into a relatively small cosmic volume under the force of gravity. "A
high rate of interactions and mergers between galaxies could be disturbing the galaxies' gas
reservoirs, igniting bursts of star formation," said Geach.

By studying the filament, astronomers will be able to explore the fundamental issue of whether
"nature" versus "nurture" matters more in the life progression of a galaxy. "Is the evolution of a
galaxy dominated by intrinsic properties such as total mass, or do wider-scale cosmic
environments largely determine how galaxies grow and change?" Geach asked. "The role of the
environment in influencing galactic evolution is one of the key questions of modern
astrophysics."

The galaxies in the RCS2319 filament will eventually migrate toward the center of the emerging
supercluster. Over the next seven to eight billion years, astronomers think RCS2319 will come to
look like gargantuan superclusters in the local universe, like the nearby Coma cluster. These
advanced clusters are chock-full of "red and dead" elliptical galaxies that contain aged, reddish
stars instead of young ones.

"The galaxies we are seeing as starbursts in RCS2319 are destined to become dead galaxies in
the gravitational grip of one of the most massive structures in the universe," said Geach. "We're
catching them at the most important stage of their evolution."

Herschel is a European Space Agency cornerstone mission, with science instruments provided by
consortia of European institutes and with important participation by NASA. NASA's Herschel
Project Office is based at NASA's Jet Propulsion Laboratory, Pasadena, Calif. JPL contributed
mission-enabling technology for two of Herschel's three science instruments. The NASA
Herschel Science Center, part of the Infrared Processing and Analysis Center at the California
Institute of Technology in Pasadena, supports the United States astronomical community.
Caltech manages JPL for NASA.

More information is online at http://www.herschel.caltech.edu ,
http://www.nasa.gov/herschel and http://www.esa.int/SPECIALS/Herschel .

-end-





To remove yourself from this mailing, please go to http://www.kintera.org/TR.asp?a=clJXIeNSJfLVIaM0G&s=hhJWIYOBKdJIKXMHLrF&m=bhKNI2PEJgKQL9K

To remove yourself from all mailings from NASA Jet Propulsion Laboratory, please go to http://www.kintera.org/TR.asp?a=5oLJITOqE8KHKQPzB&s=hhJWIYOBKdJIKXMHLrF&m=bhKNI2PEJgKQL9K