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Posts Tagged ‘theory of general relativity’

Trio Of Supermassive Black Holes Shake Space-Time


Astronomers have discovered three closely orbiting supermassive black holes in a galaxy more than 4 billion light years away. This is the tightest trio of black holes known to date and is remarkable since most galaxies have just one at their centre (usually with a mass between 1 million to 10 billion times that of the Sun). The discovery suggests that these closely packed supermassive black holes are far more common than previously thought. The team, led by South African Dr Roger Deane from the University of Cape Town, used a technique called Very Long Baseline Interferometry (VLBI) to discover the inner two black holes of the triple system. This technique combines the signals from large radio antennas separated by up to 10 000 kilometres to see detail 50 times finer than that possible with the Hubble Space Telescope. The observations were done with the European VLBI Network (EVN) and the data were correlated at the Joint Institute for VLBI in Europe (JIVE) in Dwingeloo, the Netherlands.

“What remains extraordinary to me is that these black holes, which are at the very extreme of Einstein’s Theory of General Relativity, are orbiting one another at 300 times the speed of sound on Earth”, says Deane. “Not only that, but using the combined signals from radio telescopes on four continents we are able to observe this exotic system one third of the way across the Universe. It gives me great excitement as this is just scratching the surface of a long list of discoveries that will be made possible with the Square Kilometre Array (SKA).”

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Radiation From Early Universe Found Key To Answer Major Questions In Physics


Astrophysicists at UC San Diego have measured the minute gravitational distortions in polarized radiation from the early universe and discovered that these ancient microwaves can provide an important cosmological test of Einstein’s theory of general relativity. These measurements have the potential to narrow down the estimates for the mass of ghostly subatomic particles known as neutrinos.

The radiation could even provide physicists with clues to another outstanding problem about our universe: how the invisible “dark matter” and “dark energy,” which has been undetectable through modern telescopes, may be distributed throughout the universe.

The scientists are publishing details of their achievement in the June issue of the journal Physical Review Letters, the most prestigious journal in physics, which highlighted their paper as an “editor’s suggestion” because of its importance and significance to the discipline.

The UC San Diego scientists measured variations in the polarization of microwaves emanating from the Cosmic Microwave Background—or CMB—of the early universe. Like polarized light (which vibrates in one direction and is produced by the scattering of visible light off the surface of the ocean, for example), the polarized “B-mode” microwaves the scientists discovered were produced when CMB radiation from the early universe scattered off electrons 380,000 years after the Big Bang, when the cosmos cooled enough to allow protons and electrons to combine into atoms.

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Intergalactic Space Is Filled with Dark Matter

February 14, 2012 Leave a comment

It is well known that there is a large amount of unseen matter called “dark matter” in the universe. It constitutes about 22 percent of the present-day universe while ordinary matter constitutes only 4.5 percent. An important question still remains – Where is most of the dark matter in the universe ?

Einstein’s theory of general relativity predicts that a light ray passing through near a massive object such as a galaxy is bent by the effect called “gravitational lensing”. For example, the effect causes the image of a distant galaxy to be deformed and brightened by an intervening galaxy. However the effect itself is very small and so cannot be easily detected for a single galaxy. Only recently, images of millions of galaxies from Sloan Digital Sky Survey (SDSS) made it possible to derive an averaged mass distribution around the galaxies. Earlier in 2010, an international research group led by Brice Menard then at University Toronto and Masataka Fukugita at IPMU used twenty four millions galaxy images from SDSS and successfully detected gravitational lensing effect caused by dark matter around the galaxies. From the result, they determined the projected matter density distribution over a distance of a hundred million light years from the center of the galaxies.

Full Story: http://www.ipmu.jp/node/1222