Hubble reveals cosmic framework
Hubble, XMM-Newton, and powerful ground-based telescopes provided data that let astronomers
create this 3-D map of dark matter. Clumping of the dark matter is more pronounced in the more
recent times.
"Dark matter collapsed first," says Massey. "Without it, the universe as we know it today wouldn't exist." The map shows visible galaxies then formed within the framework established by dark matter.
XMM-Newton mapped the hot gas in the survey region's galaxy clusters. This X-ray-emitting gas constitutes about 4 times the mass of a galaxy cluster's stars. Ground-based telescopes provide the color information that allowed astronomers to determine how distant the galaxies are.
But the detailed Hubble images allowed the team to glimpse weak gravitational lensing — distortions in the shapes of background galaxies caused by intervening dark matter.
visible COSMOS
This false-color image shows the distribution of normal matter in the COSMOS map. The brightest clumps correspond to the greatest density of matter. NASA / ESA / R. Massey (Caltech) [larger image]
"If you place some dark matter in the way, this dark matter — through its gravity — bends the path of light," explains Massey. The result is a 1- to 2-percent distortion of a galaxy's shape. "We understand statistically what those galaxies are supposed to look like," he says. "As the light gets deflected, it distorts the shapes of the background galaxies. So, we end up seeing them in a distorted way, as if through lots of little lenses — and each of those lenses is a bit of dark matter."
This false-color image shows the distribution of normal
matter in the COSMOS map. The brightest clumps correspond
to the greatest density of matter.
"This is the first clear view of the cosmic web," says team member Richard Ellis of Caltech. The largest visible structures are filaments spanning 60 million light-years and containing some 2 trillion times our Sun's mass. But because the COSMOS map includes information about the distance of objects, it's also the first direct measure of the growth of galaxies in dark matter over time.
More distant "slices" of the map show the state of the universe at earlier times. The astronomers termed this "cosmopaleontology."
http://www.astronomy.com/asy/default.as … mp;id=4994
Hubble, XMM-Newton, and powerful ground-based telescopes provided data that let astronomers
create this 3-D map of dark matter. Clumping of the dark matter is more pronounced in the more
recent times.
"Dark matter collapsed first," says Massey. "Without it, the universe as we know it today wouldn't exist." The map shows visible galaxies then formed within the framework established by dark matter.
XMM-Newton mapped the hot gas in the survey region's galaxy clusters. This X-ray-emitting gas constitutes about 4 times the mass of a galaxy cluster's stars. Ground-based telescopes provide the color information that allowed astronomers to determine how distant the galaxies are.
But the detailed Hubble images allowed the team to glimpse weak gravitational lensing — distortions in the shapes of background galaxies caused by intervening dark matter.
visible COSMOS
This false-color image shows the distribution of normal matter in the COSMOS map. The brightest clumps correspond to the greatest density of matter. NASA / ESA / R. Massey (Caltech) [larger image]
"If you place some dark matter in the way, this dark matter — through its gravity — bends the path of light," explains Massey. The result is a 1- to 2-percent distortion of a galaxy's shape. "We understand statistically what those galaxies are supposed to look like," he says. "As the light gets deflected, it distorts the shapes of the background galaxies. So, we end up seeing them in a distorted way, as if through lots of little lenses — and each of those lenses is a bit of dark matter."
This false-color image shows the distribution of normal
matter in the COSMOS map. The brightest clumps correspond
to the greatest density of matter.
"This is the first clear view of the cosmic web," says team member Richard Ellis of Caltech. The largest visible structures are filaments spanning 60 million light-years and containing some 2 trillion times our Sun's mass. But because the COSMOS map includes information about the distance of objects, it's also the first direct measure of the growth of galaxies in dark matter over time.
More distant "slices" of the map show the state of the universe at earlier times. The astronomers termed this "cosmopaleontology."
http://www.astronomy.com/asy/default.as … mp;id=4994
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