The name dark matter given to them as these matter neither absorb or emit light .Then you have a doubt ? when and how did scientist discover dark matter
It all started with a astronomer Rickey in 1939 . He observe a strange thing happening when he observe coma cluster(cluster means group of thousands of galaxies together),that is the revolution of the galaxy in that cluster have much 400 times higher than the theoretical revolution calculated from the normal matter in that galaxy.
Another scientist Vera ruby experience a strange behavior when observing a galaxy that is the as per the gravitation the outer planet of that galaxy should revolve slower than the original speed.
So this is the history of discovering dark matter.so you ask is there is any evidence for this .
For this scientist use a technique called gravitational lensing . this is basically when a bigger galaxy over lapses are smaller galaxy.The bigger galaxy bends the space time around it so the the light from the smaller galaxy need to travel that path to reach us .so we get a image where the smaller galaxy which is behind the galaxy to be located in the edges of the bigger galaxy.
So if instead of a bigger galaxy .Let us consider a dark matter is present. then we get a image where the behind galaxy at the edges of the image and center will be black region.
Here are they
When scientist view Pandora cluster this cluster is located 3.8 billion light years from us.
when viewing through Hubble telescope we get a image like this
In this the pink regions are regions where hot glass are present.
When two galaxy in that cluster hit each other we see that in blue regions there are gravitational lensing happen and we can't see any galaxy causing it this is because these lensing is cause by dark matter and as we can't see them so the center of the blue region appears to be black.
Has laoreet percipitur ad. Vide interesset in mei, no his legimus verterem. Et nostrum imperdiet appellantur usu, mnesarchum referrentur id vim.
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