Astrophysicists discover a quasar that acts as a cosmic lens (w/ Video)

July 20, 2010
This is an image of the first-ever foreground quasar (blue) lensing a background galaxy (red), taken with the Keck II telescope. Credit: [Credit: Courbin, Meylan, Djorgovski, et al., EPFL/Caltech/WMKO]

A quasar acting as a gravitational lens has now been observed for the first time. This discovery, made by the EPFL's Laboratory of Astrophysics in cooperation with Caltech, represents an advance in the field, since it will allow scientists to weigh and measure a galaxy that contains a quasar. The news is published today in the journal Astronomy & Astrophysics.

Gravitational lenses are common throughout the universe. They are caused by massive objects such as stars or galaxies that bend rays of light passing nearby. If these objects are between the earth and a more distant light source, the light will therefore be brighter and easier to observe, but also very distorted. If the alignment of the various stellar bodies is almost perfect, the image of the source will be multiplied.

The lens phenomenon is not only an interesting result of Einstein's theory of general relativity; it has also been a valuable astrophysical tool with important applications in the search for extrasolar planets and the study of stars, galaxies, clusters of galaxies and quasars. For example, the nature of the distortion, the number of images of the most distant objects and their position in the sky provide essential information about the distribution of matter in the lens galaxy and allow a measurement of its total matter, including dark matter, to be made.

A quasar is the heart of a galaxy, consisting of a supermassive black hole. The small fraction of the galaxy's mass that is close enough to be swallowed up by the black hole emits light before disappearing forever, giving rise to this extremely bright and transient phenomenon.

To date, about a hundred of these quasars emitting light that is concentrated by a lens galaxy located between them and the earth have been discovered. However, this is the first time that the opposite case has been observed, where the quasar is in the foreground and the galaxy behind it. The interest of this discovery lies in the fact that it provides an unprecedented opportunity to "weigh" a galaxy containing a quasar.

This video is not supported by your browser at this time.
EPFL and Caltech researchers have discovered a quasar acting as a cosmic lens, magnifying a 7.5 light year distant galaxy. Credit: EPFL

This advance was made thanks to the SLOAN Digital Sky survey database (www.sdss.org), which makes three-dimensional sky maps covering more than a quarter of the sky available to scientists and contains nearly a million and over 120,000 quasars. A sample of some 23,000 of these in the northern hemisphere was selected by the Laboratory of team. In the end, only four of them seemed to act as a .

One of these was studied using the Keck telescope (Caltech) on Mauna Kea peak in Hawaii. These images will be supplemented in the coming months with very high-quality photographs from the Hubble Space Telescope, which will reveal more about the nature of this particular quasar.

Explore further: Chandra finds evidence for quasar ignition

Related Stories

Chandra finds evidence for quasar ignition

March 23, 2006

New data from NASA's Chandra X-ray Observatory may provide clues to how quasars "turn on." Since the discovery of quasars over 40 years ago, astronomers have been trying to understand the conditions surrounding the birth ...

Astronomers discover a trio of quasars

January 8, 2007

Using ESO's Very Large Telescope and the W.M. Keck Observatory, astronomers at the Ecole Polytechnique Fédérale de Lausanne in Switzerland and the California Institute of Technology, USA, have discovered the first known ...

Galaxy 'hunting' made easy

September 14, 2007

Astronomers using ESO's Very Large Telescope have discovered in a single pass about a dozen otherwise invisible galaxies halfway across the Universe. The discovery, based on a technique that exploits a first-class instrument, ...

Trick of Nature Allows Hubble and Keck to Find Tiny Galaxy

October 5, 2007

A team of astronomers at the University of California at Santa Barbara report that they have resolved a dwarf galaxy 6 billion light-years away. Weighing only 1/100 as much as our Milky Way Galaxy, the dwarf is much smaller ...

Merging galaxies create a binary quasar (w/ Video)

February 3, 2010

Astronomers have found the first clear evidence of a binary quasar within a pair of actively merging galaxies. Quasars are the extremely bright centers of galaxies surrounding super-massive black holes, and binary quasars ...

Astronomers discover an unusual cosmic lens

July 16, 2010

Astronomers at the California Institute of Technology (Caltech) and Ecole Polytechnique Fédérale de Lausanne (EPFL) in Switzerland have discovered the first known case of a distant galaxy being magnified by ...

Recommended for you

First detection of lithium from an exploding star

July 29, 2015

The chemical element lithium has been found for the first time in material ejected by a nova. Observations of Nova Centauri 2013 made using telescopes at ESO's La Silla Observatory, and near Santiago in Chile, help to explain ...

New names and insights at Ceres

July 29, 2015

Colorful new maps of Ceres, based on data from NASA's Dawn spacecraft, showcase a diverse topography, with height differences between crater bottoms and mountain peaks as great as 9 miles (15 kilometers).

'Bathtub rings' suggest Titan's dynamic seas

July 28, 2015

Saturn's moon, Titan, is the only object in the Solar System other than Earth known to have liquid on its surface. While most of the lakes are found around the poles, the dry regions near the equator contain signs of evaporated ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.