In the year 2001 Davis Disnes and his colligues detected VIRG0H121 in the virgo culster about 5 million light years away - an invisible galaxy made almost entirely of dark matter - the first ever detected. A dark galaxy is an area in the universe containing a large amount of mass that rotates like a galaxy, but contains no stars. Without any stars to give light, it could only be found using radio telescopes. The big Question is does a Dark Galaxy really exist? Devoid of light and gas? The question is associated with understanding how the universe bloosomed from the big bang as we consider. According to increasingly refined story 85% of the matter in the universe is not ordinary baryonic matter-that makes up galaxies and stars and planets. Rather it is dark matter. As the universe grew from its infancy, the dark matter condensed in to enormous filaments like tubes, clumps and haloes. These weighty objects pooled in hydrogen gas which formed the galaxies and stars. Simulations show that dark matter should have myriad clumps between 1/1000 and 1/1000,000 as massive as our milky way galaxy. At first these small haloes should have accumulated gas and lit up as small dwarf galaxies thousands of which should whiz around Milky Way. So far astronomy could have few near by. Various factors kept the small halos dark. So space should have many dark galaxies.
Astronomers using the Hubble Space Telescope are examining one of the largest structures in the universe as part of a quest to understand the violent lives of galaxies. Hubble is providing evidence of unseen dark matter tugging on galaxies in the crowded, rough-and-tumble environment of a massive supercluster of hundreds of galaxies. Dark matter is an invisible form of matter that accounts for most of the universe’s mass. Hubble’s Advanced Camera for Surveys has mapped the invisible dark matter scaffolding superclusters as well as the detailed structure of individual galaxies embedded in it.
The dark matter map was constructed by measuring the distorted shapes of over 60,000 faraway galaxies. To reach Earth, the galaxies’ light traveled through the dark matter that surrounds the supercluster galaxies and was bent by the massive gravitational field. Heymans used the observed, subtle distortion of the galaxies’ shapes to reconstruct the dark matter distribution in the supercluster using a method called weak gravitational lensing. The dark matter map is 2.5 times sharper than a previous ground-based survey of the supercluster.