CfA: Ghosts of the Future: Giant Structures of the Universe

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CfA: Ghosts of the Future: Giant Structures of the Universe

Post by bystander » Wed Oct 13, 2010 2:14 pm

Ghosts of the Future: First Giant Structures of the Universe
Harvard-Smithsonian Center for Astrophysics | 13 Oct 2010
[img3="An infrared/optical representative-color image of a massive galaxy cluster located 7 billion light-years from Earth. This cluster weighs as much as 800 trillion Suns. Galaxies with "old" stellar populations, like modern-day ellipticals, are circled in yellow; galaxies with "young" stellar populations, like modern-day spirals, are circled in blue.
Credit: Infrared Image: NASA/JPL-Caltech/M. Brodwin (CfA)
Optical Image: CTIO Blanco 4-m telescope/J. Mohr (LMU Munich)
"] ... /lores.jpg[/img3]
Astronomers using the South Pole Telescope report that they have discovered the most massive galaxy cluster yet seen at a distance of 7 billion light-years. The cluster (designated SPT-CL J0546-5345) weighs in at around 800 trillion Suns, and holds hundreds of galaxies.

"This galaxy cluster wins the heavyweight title. It's among the most massive clusters ever found at this distance," said Mark Brodwin, a Smithsonian astronomer at the Harvard-Smithsonian Center for Astrophysics. Brodwin is first author on the paper announcing the discovery, which appeared in the Astrophysical Journal.

Redshift measures how light from a distant object has been stretched by the universe's expansion. Located in the southern constellation Pictor (the Painter), the cluster has a redshift of z=1.07. This puts it at a distance of about 7 billion light-years, meaning we see it as it appeared 7 billion years ago, when the universe was half as old as now and our solar system didn't exist yet.

Even at that young age, the cluster was almost as massive as the nearby Coma cluster. Since then, it should have grown about four times larger. If we could see it as it appears today, it would be one of the most massive galaxy clusters in the universe.
SPT-CL J0546-5345: A Massive z>1 Galaxy Cluster Selected Via the
Sunyaev-Zel'dovich Effect with the South Pole Telescope
- M Brodwin et al Galaxy Clusters Selected with the Sunyaev-Zel'dovich Effect
from 2008 South Pole Telescope Observations
- K Vanderlinde et al