Shedding light on the cosmic skeletonNovember 03, 2009"Matter is not distributed uniformly in the Universe," says Masayuki Tanaka from ESO, who led the new study. "In our cosmic vicinity, stars form in galaxies and galaxies usually form groups and clusters of galaxies. The most widely accepted cosmological theories predict that matter also clumps on a larger scale in the so-called 'cosmic web', in which galaxies, embedded in filaments stretching between voids, create a gigantic wispy structure." These filaments are millions of light years long and constitute the skeleton of the Universe: galaxies gather around them, and immense galaxy clusters form at their intersections, lurking like giant spiders waiting for more matter to digest. Scientists are struggling to determine how they swirl into existence. Although massive filamentary structures have been often observed at relatively small distances from us, solid proof of their existence in the more distant Universe has been lacking until now. The team led by Tanaka discovered a large structure around a distant cluster of galaxies in images they obtained earlier. They have now used two major ground-based telescopes to study this structure in greater detail, measuring the distances from Earth of over 150 galaxies, and, hence, obtaining a three-dimensional view of the structure. The spectroscopic observations were performed using the VIMOS instrument on ESO's Very Large Telescope and FOCAS on the Subaru Telescope, operated by the National Astronomical Observatory of Japan. Thanks to these and other observations, the astronomers were able to make a real demographic study of this structure, and have identified several groups of galaxies surrounding the main galaxy cluster. They could distinguish tens of such clumps, each typically ten times as massive as our own Milky Way galaxy -and some as much as a thousand times more massive - while they estimate that the mass of the cluster amounts to at least ten thousand times the mass of the Milky Way. Some of the clumps are feeling the fatal gravitational pull of the cluster, and will eventually fall into it. "This is the first time that we have observed such a rich and prominent structure in the distant Universe," says Tanaka. "We can now move from demography to sociology and study how the properties of galaxies depend on their environment, at a time when the Universe was only two thirds of its present age." The filament is located about 6.7 billion light-years away from us and extends over at least 60 million light-years. The newly uncovered structure does probably extend further, beyond the field probed by the team, and hence future observations have already been planned to obtain a definite measure of its size. ESO |
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| Related Galaxy Cluster Current Events and Galaxy Cluster News Articles Rapid star formation spotted in 'stellar nurseries' of infant galaxies The Universe's infant galaxies enjoyed rapid growth spurts forming stars like our sun at a rate of up to 50 stars a year, according to scientists at Durham University. Galaxy cluster smashes distance record The most distant galaxy cluster yet has been discovered by combining data from NASA's Chandra X-ray Observatory and optical and infrared telescopes. Stripped down: Hubble highlights 2 galaxies that are losing it Ram pressure is the drag force that results when something moves through a fluid - much like the wind you feel in your face when bicycling, even on a still day - and occurs in this context as galaxies orbiting about the centre of the cluster move through the intra-cluster medium, which then sweeps out gas from within the galaxies. Turbulence responsible for black holes' balancing act We live in a hierarchical Universe where small structures join into larger ones. Earth is a planet in our Solar System, the Solar System resides in the Milky Way Galaxy, and galaxies combine into groups and clusters. Galaxies coming of age in cosmic blobs The "coming of age" of galaxies and black holes has been pinpointed, thanks to new data from NASA's Chandra X-ray Observatory and other telescopes. Ghost Remains After Black Hole Eruption NASA's Chandra X-ray Observatory has found a cosmic "ghost" lurking around a distant supermassive black hole. This is the first detection of such a high-energy apparition, and scientists think it is evidence of a huge eruption produced by the black hole. Suzaku Snaps First Complete X-ray View of a Galaxy Cluster The joint Japan-U.S. Suzaku mission is providing new insight into how assemblages of thousands of galaxies pull themselves together. Giant Galaxy Messier 87 finally sized up Using ESO's Very Large Telescope, astronomers have succeeded in measuring the size of giant galaxy Messier 87 and were surprised to find that its outer parts have been stripped away by still unknown effects. The NASA/ESA Hubble Space Telescope provides new evidence for dark matter around small galaxies The NASA/ESA Hubble Space Telescope has uncovered a strong new line of evidence that galaxies are embedded in halos of dark matter. Exceptionally deep view of strange galaxy A spectacular new image of an unusual spiral galaxy in the Coma Galaxy Cluster has been created from data taken by the Advanced Camera for Surveys on the NASA/ESA Hubble Space Telescope. More Galaxy Cluster Current Events and Galaxy Cluster News Articles |
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