20% of the universe is dark matter, and 70% is dark energy. About 5% is 'normal matter': you, the stars, the visible and detectable universe. Has the Keck observatory found signs of dark matter? Maybe. Maybe not.
Daily Mail - Web of dark matter seen for the first time. Giant 'cosmic flashlight' illuminates hidden network that could help reveal mysteries of the universe.
This particular quasar, located 10 billion light-years away, illuminated a vast nebula of diffuse gas to reveal the network of filaments that connect galaxies in a cosmic web.
For years, cosmologists have been running computer simulations of the structure of the universe to develop what they refer to as the ‘standard model of cosmology’. Their calculations suggest that as the universe grows, matter becomes clustered like a huge cosmic web, weaving its way into in filaments and nodes under the force of gravity.
The latest results from the 10-metre Keck telescope in Hawaii, are reported by scientists from the University of California, Santa Cruz and the Max Planck Institute for Astronomy in Heidelberg. ‘This is a very exceptional object: it's huge, at least twice as large as any nebula detected before, and it extends well beyond the galactic environment of the quasar,’ said first author Sebastiano Cantalupo, a postdoctoral fellow at UC Santa Cruz.
The distance to the quasar is so great that the emitted light is ‘stretched’ by the expansion of the universe from an invisible ultraviolet wavelength to a visible shade of violet by the time it reaches the Keck Telescope. ‘We have studied other quasars this way without detecting such extended gas,’ Professor Cantalupo said. The light from the quasar is like a flashlight beam, and in this case we were lucky that the flashlight is pointing toward the nebula and making the gas glow.’
In an earlier survey of distant quasars using the same technique to look for glowing gas, researchers detected so-called ‘dark galaxies,’ the densest knots of gas in the cosmic web. These dark galaxies are thought to be either too small or too young to have formed stars. ‘The dark galaxies are much denser and smaller parts of the cosmic web,’ said Professor Cantalupo. ‘In this new image, we also see dark galaxies, in addition to the much more diffuse and extended nebula.‘Some of this gas will fall into galaxies, but most of it will remain diffuse and never form stars.’
While the observations support the computer simulations' picture of a cosmic web, the researchers' results suggest there is around 10 times more gas in the nebula than predicted. They believe the discrepancy may be due to limitations in the spatial resolution of the current models. It could be because the current grid-based models are missing some aspect of the underlying physics of how galaxies form and interact with quasars, they suggest. ‘These observations are challenging our understanding of intergalactic gas and giving us a new laboratory to test and refine our models,’ Professor Cantalupo said.
Source (see pictures) -
http://www.dailymail.co.uk/sciencetech/article-2542795/x.html
Keck Observatory report -
http://www.keckobservatory.org/recent/entry/ucsc_scientists_capture_first_cosmic_web_filaments_at_keck_observatory
RELATED:Dark matter and dark energy -
http://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy/
More on dark matter and dark energy on this blog -
http://ottersandsciencenews.blogspot.ca/search/label/Dark%20Matter%20and%20Dark%20Energy
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