Herschel Space Observatory Finds Galaxy-packed Supercluster
May 18, 2012

Herschel Space Observatory Finds Galaxy-packed Supercluster

Researchers from McGill University in Canada, utilizing a European space telescope, have discovered a dazzling display of billions of new stars in a galaxy-packed filament about 4,500 light years away in the Cygnus-X star-forming region of the Cygnus constellation.

The Herschel Space Observatory´s discovery shows a filament connecting two clusters of galaxies that, along with a third cluster, will smash together and provide astronomers with one of the largest galaxy superclusters in the universe.

The filament is the first of its kind to be viewed by astronomers, who are given 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,” said Kristen Coppin, an astrophysicist at McGill University in Canada, and lead author of a new paper.

“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,” added coauthor Jim Geach, also based at McGill.

Publishing their study in the Astrophysical Journal Letters, the research team explained that the intergalactic filament contains hundreds of galaxies spanning 8 million light years and links two of 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.

The Herschel observatory sees exceptionally well in far-infrared wavelengths, allowing researchers to study stellar nurseries like Cygnus-X. In a new photo accompanying the paper, bright white areas highlight areas where large stars have recently formed out of such clouds, researchers said.

Launched in May 2009, Herschel is the largest infrared telescope ever put into space. It has a primary mirror approximately 11.5 feet wide. It allows astronomers to study some of the coldest objects in the universe, the researchers said. Herschel was originally called the Far Infrared and Sub-millimeter Telescope (FIRST), but was later renamed in honor of Britain´s Sir William Herschel, who, in 1800, discovered that the light spectrum extends beyond what we can see into infrared regions.

The amount of infrared light observed suggests that the galaxies in the filament are producing the equivalent of around 1,000 solar masses of new stars per year. That´s 1,000 times more than what our own Milky Way galaxy produces each year.

Researchers believe the extreme pace of star formation in the filament is due to the fact that galaxies within the filament are being packed 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” vs. “nurture” matters more in the life progression of a galaxy.

Geach asked: “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?”

“The role of the environment in influencing galactic evolution is one of the key questions of modern astrophysics,” he said.

The galaxies in the RCS2319 filament will eventually fill the core of the emerging supercluster, and over the next several billion years, astronomers believe the filament will come to look like enormous superclusters in the local universe. These advanced clusters are heaving with “red and dead” elliptical galaxies that contain aged dying stars instead of young thriving ones.

These galaxies are “destined to become dead galaxies,” added Geach, and “we´re catching them at the most important stage of their evolution.”