Latest Weak gravitational lensing Stories

2008-09-20 09:00:00

A Unique Way to Measure Dark Energy With Galaxies and Quasars The Sloan Digital Sky Survey (SDSS) uses a 2.5-meter telescope with a wider field of view than any other large telescope, located on a mountaintop in New Mexico called Apache Point and devoted solely to mapping the universe. We now know that some three-quarters of the universe consists of dark energy, whose very existence was unsuspected when telescope construction began in 1994 and still controversial when the first Sloan survey...

2008-02-21 13:16:22

A University of British Columbia astronomer with an international team has discovered the largest structures of dark matter ever seen. Measuring 270 million light-years across, these dark matter structures criss-cross the night sky, each spanning an area that is eight times larger than the full moon. "The results are a major leap forward since the presence of a cosmic dark matter web that extends over such large distances has never been observed before," says Ludovic Van Waerbeke, an...

2008-02-19 09:05:00

Astronomers using NASA's Hubble Space Telescope have compiled a large catalog of gravitational lenses in the distant universe. The catalog contains 67 new gravitationally lensed galaxy images found around massive elliptical and lenticular-shaped galaxies. This sample demonstrates the rich diversity of strong gravitational lenses. If this sample is representative, there would be nearly half a million similar gravitational lenses over the whole sky. The lenses come from a recently completed,...

2008-01-10 10:55:00

Astronomers are using NASA's Hubble Space Telescope to dissect one of the largest structures in the universe as part of a quest to understand the violent lives of galaxies. Hubble is providing indirect evidence of unseen dark matter tugging on galaxies in the crowded, rough-and-tumble environment of a massive supercluster of hundreds of galaxies. Dark matter is an invisible form of matter that accounts for most of the universe's mass. Hubble's Advanced Camera for Surveys has mapped the...

2007-08-16 12:20:00

Astronomers have discovered a chaotic scene unlike any witnessed before in a cosmic "train wreck" between giant galaxy clusters. NASA's Chandra X-ray Observatory and optical telescopes revealed a dark matter core that was mostly devoid of galaxies, which may pose problems for current theories of dark matter behavior. "These results challenge our understanding of the way clusters merge," said Dr. Andisheh Mahdavi of the University of Victoria, British Columbia. "Or, they possibly make us even...

2007-03-05 11:15:46

By analyzing the COSMOS field, the largest field of galaxies ever observed with the Hubble space telescope, an international team of scientists led by researchers from the California Institute of Technology (United States) and researchers from the associated laboratories of the CNRS and the CEA , made the first three-dimensional map of dark matter in the Universe using gravitational lensing effects. This historic first seems to confirm the standard theories on the formation of the large...

2007-01-07 15:50:00

SEATTLE - An international team of astronomers using NASA's Hubble Space Telescope has created the first three-dimensional map of the large-scale distribution of dark matter in the universe. Dark matter is an invisible form of matter whose total mass in the universe is more than five times that of "normal" matter (i.e., atoms). The nature of dark matter is still unknown. Its presence in the universe is inferred from its current influence within galaxies and clusters of galaxies, and the...

2005-11-17 12:33:45

NASA -- As Albert Einstein developed his theory of general relativity nearly a century ago, he proposed that the gravitational field from massive objects could dramatically warp space and deflect light. The optical illusion created by this effect is called gravitational lensing. It is nature's equivalent of having a giant magnifying lens in space that distorts and amplifies the light of more distant objects. Einstein described gravitational lensing in a paper published in 1936. But he...

2005-09-08 10:40:00

Alabama -- A new analysis of 'cool' spots in the cosmic microwave background may cast new doubts on a key piece of evidence supporting the big bang theory of how the universe was formed. Two scientists at The University of Alabama in Huntsville (UAH) looked for, but couldn't find, evidence of gravitational "lensing" where you might expect to find it, in the most distant light source in the universe -- the cosmic microwave background. Results of this research by Dr. Richard Lieu, a UAH...

2005-06-30 13:05:00

Using ESO's Very Large Telescope, R©mi Cabanac and his European colleagues have discovered an amazing cosmic mirage, known to scientists as an Einstein Ring. This cosmic mirage, dubbed FOR J0332-3557, is seen towards the southern constellation Fornax (the Furnace), and is remarkable on at least two counts. First, it is a bright, almost complete Einstein ring. Second, it is the farthest ever found. "There are only a very few optical rings or arcs known, and even less so in which the lens...

Latest Weak gravitational lensing Reference Libraries

2010-09-07 17:31:13

The Bullet Cluster is made up of two colliding clusters galaxies. According to a 2006 study, the Bullet Cluster also shows the best evidence for the existence of Dark Matter. From observations of galaxy cluster collisions it has been found that many show displacement between their center of visible matter and their gravitational potential. Each component, stars, gas, and dark matter, within a cluster pair behaves differently during a collision allowing for each to be studied separately....

2004-10-19 04:45:41

Gravitational Lens -- A gravitational lens is formed when the light from a very distant, bright object (such as a quasar) is "bent" around a massive object (such as a massive galaxy) between the bright object and the viewer. The process is known as gravitational lensing, and was one of the predictions made by Einstein's general relativity. Description In a gravitational lens, the gravity from the massive object bends light as a lens might. As a result, the path of the light from a...

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Word of the Day
  • The call or cry of a bird or other animal to its mate or its young.
'Call-note' is newer than 'bird-call,' which originally referred to 'an instrument for imitating the note of birds' but now also refers to 'the song or cry of a bird.'