Jump to: navigation , search. Let us make our definitions a little more strict. Category : Horizons. Navigation menu Personal tools Log in. Namespaces Page Discussion. Views Read View source View history. Content 1. For example, based on an overabundance of positrons measured by a satellite-based detector called the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics PAMELA , scientists expected that positrons from dark matter would be found at energy levels higher than 10 gigaelectron volts GeV , said study co-author Veronica Bindi, a physicist at the University of Hawaii.
And the positrons found by AMS increase in abundance from 10 GeV to GeV, with the slope of the increase reducing by an order of magnitude over the range from 20 GeV to GeV — just what scientists expect from positrons created by dark-matter annihilations.
Furthermore, the positrons appear to come from all directions in space, and not a single source in the sky. Retrieved 19 December Physics Letters B. Bibcode : PhLB..
Gunter's Space Page. Retrieved 18 December NASA Spaceflight. The bottom panel shows a numerical model that matches the data remarkably well, from using the combined gravitational influence of luminous and dark matter. Image credit: M. Since this discovery 40 years ago, we have learned that this mysterious substance, which is probably an exotic elementary particle, makes up about 85 percent of the mass in the universe, leaving only 15 percent to be the ordinary stuff encountered in our everyday lives.
Dark matter is central to our understanding of how galaxies form and evolve — and is ultimately one of the reasons for the existence of life on Earth — yet we know almost nothing about it. The speeds of stars on circular orbits have been measured around both spiral and elliptical galaxies.
Telescopes cannot see events earlier than about , years after the Big Bang , when the universe became transparent the cosmic microwave background ; this corresponds to the particle horizon at a distance of about 46 billion 4.
Since the matter causing the net motion in this proposal is outside this range, it would in a certain sense be outside our visible universe ; however, it would still be in our past light cone. The results appeared in the October 20, , issue of Astrophysical Journal Letters.
In , data from the Planck space telescope showed no evidence of "dark flow" on that sort of scale, discounting the claims of evidence for either gravitational effects reaching beyond the visible universe or existence of a multiverse.
The dark flow was determined to be flowing in the direction of the Centaurus and Hydra constellations. However, the source of the Great Attractor's attraction was thought to originate from a massive cluster of galaxies called the Norma Cluster , located about million light-years away from Earth.
In a study from March , Kashlinsky extended his work from , by using the 5-year WMAP results rather than the 3-year results, and doubling the number of galaxy clusters observed from The team also sorted the cluster catalog into four "slices" representing different distance ranges. They then examined the preferred flow direction for the clusters within each slice. This parameter adds some random variation to the rotation. Posted in pflow. Reblogged this on joshpurple.
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