Distant Galaxy Collision Imaged Through Gravitational Lensing

The European Southern observatory and with the help of other agencies, has imaged a galactic collission that happened when the Universe was half its age using gravitational lensing.

Using state of the art instruments from all around the world, on the ground and in space, ESO has imaged galaxy H-ATLAS J142935.3-002836 in collision with another galaxy.

With the help of gravitational lensing which uses Einstein's theory that light can be bent given enough mass, scientists were able to study objects which would not be visible otherwise and to directly compare local galaxies with much more remote ones, seen when the Universe was significantly younger.

The image above shows the foreground galaxy that is doing the lensing, which resembles how our home galaxy, the Milky Way, would appear if seen edge-on. But around this galaxy there is an almost complete ring — the smeared out image of a star-forming galaxy merger far beyond.

In his theory of general relativity, Einstein predicted that given enough mass, light does not travel in a straight line but will be bent in a similar way to light refracted by a normal lens.”

Gravitational lensing is done with the help of galaxies and galaxy clusters which provides the mass that deflects light from objects behind them due to their strong gravity. The magnifying properties of this effect allow astronomers to study these objects.

The collision of H-ATLAS J142935.3-002836 was gathered using three ESO telescopes, the ALMA, APEX and VISTA, and with assistance of other telescopes and surveys namely: NASA/ESA Hubble Space Telescope, the Gemini South telescope, the Keck-II telescope, the NASA Spitzer Space Telescope, the Jansky Very Large Array, CARMA, IRAM and SDSS and WISE.

Extremely Rare Gravitational Lensed Dwarf Galaxy Imaged By Hubble Space Telescope

This picture from the NASA/ESA Hubble Space Telescope shows the most distant gravitational lens yet discovered. The glow at the centre of this picture is the central regions of a normal galaxy. By chance it is precisely aligned with a much more remote, young star-forming galaxy. The light from the more distant object is bent around the nearer object by its strong graviational pull to form a ring of multiple images. The chance of finding such an exactl alignment is very small, suggesting that there may be more star-forming galaxies in the early Universe than expected.
Credit: NASA/ESA/A. van der Wel

The Hubble Space Telescope as part of the CANDELS and COSMOS survey has captured an extremely rare and very distant dwarf galaxy that is gravitationally lensed. The dwarf galaxy is a record 9.4 billion light years away. It is a young starburst galaxy that forms a perfect Einstein ring, indicating a gravitational lens with very precise alignment of the lens and the background light source.

When two objects (the light source and a lensing mass) is observed, the light from the source is bent and deflected by the gravity of the lensing mass. It allows scientists to measure the mass of the lensing mass as well as the surrounding dark matter (which does not interact with light and only can be detected by gravitational effects).

Similar to looking at an object through a wine glass, the light is bent and forms a circle which is called an Einstein ring. The lens also magnifies the background light source, acting as a "natural telescope" that allows astronomers a more detailed look at distant galaxies than is normally possible.

In the captured image, the formation of the lens is extremely rare as the alignment has a one millimeter separation at a distance of 20 kilometers - a near perfect alignment.