TWO IMAGES OF ABELL 1689 TAKEN. TINT BLUE COLOR IN THE BOTTOM IMAGE SHOWS LOCATION OF DARK MATTER.NASA's Jet Propulsion Laboratory at California released an image taken by Hubble Space Telescope of Galaxy cluster Abell 1689 situated about 2.2 billion light years away showing distorted image of the galaxy cluster along with a tint blue shade at the center of the cluster.
Gravitational Lensing-
As predicted by Einstein's Theory of General Relativity, an object having dense mass will bend the light travelling near it as the Universe consists of fabric of Space and Time which bend due to the presence of mass. In Optical lens, a similar bending can be produced with maximum at lens position away from the center and minimum when lens position is near the center.
For Gravitational lensing, maximum bending will happen at the center of the lens and as the object moves away from the center, bending of light rays will be minimized giving less lensing.
Dark Matter-
Dark matter in typical definitions is a hypothetical (NOW INFERRED) form of matter that contributes to 80% of total matter in Universe ( 20% is visible matter)
Dark matter due to its vast amount in a galaxy cluster has helped the formation of galaxies and the universe assisting the force of gravitation.
Tendency of Dark matter is of not reacting with electromagnetism ( EM radiations) As a result of which they can't be detected by EM waves hence known as DARK.
There are three types of Dark matter
HOT,WARM,COLD dark matter....
Image of Abell 1689.
In the captured image, gravitational lensing is clearly seen as the distorted image has formed near the center of the cluster. This is considered as the actual mass of the entire cluster. Further astronomers count the mass of visible components like stars planets etc.
Subtraction of the mass calculated due to lensing and mass of visible components gives the amount of dark matter. The amount of Dark Matter is several times more than was expected by astronomers and it means galaxies had formed quite before than Dark Energy started expanding space between two galaxy. The image has clarified that more dark matter has been there at the center than expected
~ Akshay Deoras
