New Delhi: The 8.1 metre Gemini North Telescope in Hawaii has peered into the Perseus Cluster, with the elliptical galaxy NGC 1270 taking centre stage. There are thousands of galaxies within the Perseus Cluster, that is about 240 million lightyears from Earth. NGC 1270 was first discovered in 1863, before astronomers had developed the idea of galaxies, that were initially described as nebulae because of their cloudy appearance. Astronomers have previously detected strong electromagnetic energy radiating from the heart of NGC 1270, that harbours a supermassive black hole that is voraciously feeding on the surrounding gas and dust. About 10 percent of all galaxies have such actively feeding, or bright black holes.
Galaxy clusters also contain tremendous quantities of dark matter, a mysterious substance that does not interact with light, but interacts with regular or baryonic matter through gravity. Once astronomers were convinced of the existence of galaxies other than the Milky Way in 1924, after Edwin Hubble discovered stars within what were believed to be nebulae, they measured the masses of galaxies using the visible stars. It is then that astronomers discovered that galaxies, including the Milky Way, could not possibly maintain their shapes just by the mass of all the visible stars they contain. This invisible mass was dubbed dark matter.
Dark Matter and Galaxy Cli\usters
If there was no dark matter, then galaxies would be spread out evenly across space, rather than clumping up together in galaxy clusters. Scientists suspect that an invisible web of dark matter draws galaxies together where tendrils of the mysterious substance cross, and consequently have the strongest gravitational influence. Despite decades of searching, scientists do not understand the nature of dark matter. Galaxy clusters, with their strong gravitational lensing, allows astronomers to probe the mysteries of dark matter. There are thousands of background galaxies of all shapes and sizes visible in the image.
