Gravitational Lensing | Universe Today

Even Albert Einstein might have been impressed. His theory of general relativity, which describes how the gravity of a massive object, such as a star, can curve space and time, has been used to predict small shifts in the orbit of Mercury, gravitational lensing by galaxies and black holes, and the existence of gravitational waves.  Now, new research shows it may soon be possible to study the effects of general relativity in bench-top laboratory experiments.

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Using a technique called Pixel-lensing, a group of astronomers in Italy may have detected a planet orbiting another star. But this planet is unique among the 300-plus exoplanets discovered so far, as it and its parent star are in another galaxy. The Andromeda Galaxy, to be exact. Technically, the star in M31 was found to have a companion about 6 times the mass of Jupiter, so it could be either a brown dwarf or a planet. But either way, this is a remarkable feat, to find an object of that size in another galaxy.
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Astronomers have found the most distant signs of water in the Universe to date. The water vapor is thought to be contained in a maser, a jet ejected from a supermassive black hole at the center of a galaxy, named MG J0414+0534. The radiation from the water maser was emitted when the Universe was only about 2.5 billion years old, a fifth of its current age. "The radiation that we detected has taken 11.1 billion years to reach the Earth, said Dr. John McKean of the Netherlands Institute for Radio Astronomy (ASTRON). "However, because the Universe has expanded like an inflating balloon in that time, stretching out the distances between points, the galaxy in which the water was detected is about 19.8 billion light years away."
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A long time ago in a galaxy far, far away there was water. Astronomers have found tell-tale signatures of water molecules in a galaxy more than 11 billion light years from Earth. Using the giant, 100-meter-diameter radio telescope in Effelsberg, Germany, along with the Very Large Array (VLA) in New Mexico, scientists detected the most distant water yet seen in the Universe. Previously, the most distant water had been seen in a galaxy less than 7 billion light-years from Earth. Since it is so far away, we're actually seeing it as it was long ago; as when the Universe was one-sixth the age it is now. The astronomers were able to take advantage of two types of natural "amplification" to detect the water in this galaxy. The galaxy, dubbed MG J0414+0534 has a quasar — a supermassive black hole powering bright emission — at its core. In the region near the core, the water molecules are acting as masers, the radio equivalent of lasers, to amplify radio waves at a specific frequency. Additionally, another galaxy was used as a gravitational lens to magnify the radio signals used to detect the water molecules.
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Using gravitational lensing, astronomers have been able to see a young star-forming galaxy in the distant universe as it appeared only two billion years after the Big Bang. Appropriately enough, the galaxy used as a zoom lens was the "Cosmic Eye" galaxy, named so because through the effect of gravitational lensing, it looks like a giant eye in space. The researchers, led by Dr. Dan Stark, of Caltech, say this distant galaxy may provide insights into how our own galaxy may have evolved to its present state.
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A powerful collision of galaxy clusters captured by NASA's Hubble Space Telescope and Chandra X-ray Observatory provides evidence for dark matter and insight into its properties. Observations of the cluster known as MACS J0025.4-1222 indicate that a titanic collision has separated dark matter from ordinary matter. The images also provide an independent confirmation of a similar effect detected previously in a region called the Bullet Cluster. Like the Bullet Cluster, this newly studied cluster shows a clear separation between dark and ordinary matter.
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An international team of astronomers have compiled the largest-ever single collection of "gravitational lens" galaxies, and their survey yielded information on the masses of galaxies, including an inference of the amount of dark matter. Gravitational lensing occurs when two galaxies happen to aligned with one another along our line of sight in the sky. The gravitational field of the nearer galaxy distorts the image of the more distant galaxy into multiple arc-shaped images. Sometimes this effect even creates a complete ring, known as an "Einstein Ring." The findings of this survey helps settle a long standing debate over the relationship between and mass and luminosity in galaxies.
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It is well documented that dark matter makes up the majority of the mass in our universe. The big problem comes when trying to prove dark matter really is out there. It is dark, and therefore cannot be seen. Dark matter may come in many shapes and sizes (from the massive black hole, to the tiny neutrino), but regardless of size, no light is emitted and therefore it cannot be observed directly. Astronomers have many tricks up their sleeves and are now able to indirectly observe massive black holes (by observing the gravitational, or lensing, effect on light passing by). Now, large-scale structures have been observed by analyzing how light from distant galaxies changes as it passes through the cosmic web of dark matter hundreds of millions of light years across…
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As the search for extrasolar planets continues, researchers are finding systems more and more like our own Solar System. And today researchers announced another significant find: a system with two planets smaller than Jupiter and Saturn. It's almost starting to sound like home.
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As galaxies come together through successive mergers they take on the splendid spiral shape like our own Milky Way. Keep merging those larger galaxies, though, and you'll eventually get an elliptical galaxy – a gigantic diffuse cloud of ancient stars with little structure. Such a galaxy, NGC 1132, was recently photographed by the Hubble Space Telescope.
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Finding a black hole is an easy task… compared with searching for a wormhole. Suspected black holes have a massive gravitational effect on planets, stars and even galaxies, generating radiation, producing jets and accretion disks. Black holes will even bend light through gravitational lensing. Now, try finding a wormhole… Any ideas? Well, a Russian researcher thinks he has found an answer, but a highly sensitive radio telescope plus a truckload of patience (I'd imagine) is needed to find a special wormhole signature…
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Astronomers have several techniques to discover planets. But one of the least used so far, gravitational microlensing, might be just the right technique to find planets in the habitable zone of nearby dwarf stars.
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Black holes are already plenty bizarre. Imagine all the mass of several suns compressed down into an object of potentially infinitely small size. But what if you could find an object that's even stranger: a theoretical "naked singularity"; a black hole spinning so quickly that it lacks an event horizon. A point in space where the density is infinite, yet still visible from the outside.
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Astronomers announced today that they've located the most distant galaxies ever seen, 13.2 billion light-years away, formed when the Universe was only 500 million years old.

Galaxies that far away can't easily be seen directly with current telescopes. Instead, the researchers turned massive clusters of galaxies into natural telescopes, using a technique called gravitational lensing. As the light from the more distant galaxies passed the galaxy clusters, it was bent by gravity towards the Earth.
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A clever trick has enabled NASA's Spitzer Space Telescope to calculate the distance to a distant object, confirming that it's part of our Milky Way. An even more intriguing finding is that the object is probably a binary pair of black holes, orbiting one another – an extremely rare thing to see.
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