NASA peers into the purview of space using its proverbial telescopic eye. The Hubble Space Telescope, one of the few satellites that needs no introduction, examined four of the oldest galaxies known to populate the universe. The galaxies are tangled in a cluster known as Abell 2774, and they stretch 13.2 billion years in time. They are perhaps the earliest vestiges to seed the universe with stars – just five-hundred million years after the initial big bang.
The insights provided by the Hubble Space Telescope was not a lone exercise, however. NASA fused data provided by the Hubble Space Telescope and the Spitzer Space Telescope together. Both telescopes are capable of looking into the far reaches of space by peering past a dense degree of intergalactic material. The telescopes paint a picture of Abell 2774 that radiates a blue tint. The blue tint is an indication of rapid star formation. Astronomers long discovered galaxies consisting largely of nebulous gas in the early universe; yet none have been found teeming with the amount of stars as Abell 2774.
The galaxies embedded in Abell 2774 range in size and luminosity. The brightest galaxy is roughly one-hundred times larger than our own galaxy, whereas others dwarf one-thousandth the size of the Milky Way. When NASA peers into the purview of space, the blue light that Abell 2774 emits excites astronomers. Yet the light only constitutes five-percent of the galaxy cluster’s mass. Roughly twenty-five percent of the rest of the mass is attributed to gas and seventy-five percent is attributed to dark matter. By mapping the respective masses of Abell 2774, NASA is even more excited to potentially shed light on the substance that refuses to reflect light itself – dark matter.
Dark matter, or perhaps a more appropriate term is dark gravity, is an unaccounted force (particle, field, thing; no one knows what.) that prevents galaxies from falling a part. Gravity is the glue that holds the cosmos together. Yet when physicists calculate all the gravity attributed to stars, gas and nebulae in a single galaxy, it is not enough to actually cement the stars into an ill-defined, celestial sphere. Therefore, physicists reason their must be an alternative source of gravity that is not accounted by the observed matter alone.
Discovering the source of dark matter is a shoe-in for the Nobel Prize. It is therefore unsurprising that every physicists wants a piece of the pie. Particles physicists hold dark matter is an unaccounted particle, and general relativists (physicists who specialize in Einstein’s Theory of General Relativity) latch to the idea that dark matter is an imprecise calculation that will vanish when a more approximate theory of gravity is developed. Then there are string theorists who speculate dark matter is the manifestation of a parallel universe that permeates through a membrane connected to our own universe. The possibilities are endless. In short: Given the nature of dark matter, physicists are quite literally shooting in the dark.
Astronomers hope they can narrow there search for the source of dark matter by gravitational lensing. Gravitational lensing is a phenomena that occurs when light is bent by the gravitational field of an object. Galaxy clusters are an excellent source to observe this phenomena due to the massive gravitational fields they emit. NASA wishes to use Abell 2774 to observe this phenomena.
By mapping the distortion of light bent around Abell 2774, scientists can identify where exactly the nugget of dark matter lies. Pinpointing the exact source of dark matter would be a major breakthrough in astronomy. Yet, as is always the case when NASA peers into the purview of space, the resolution to one cosmic mystery simply unravels a new one.
By Nathan Cranford