Have we finally found DARK MATTER? Gamma rays hint at the presence of the mysterious material in nearby dwarf galaxy
comments
Astronomers may have finally found evidence of the elusive dark matter that permeates the universe.
Its presence has potentially been spotted in a dwarf matter orbiting the Milky Way which is radiating gamma rays - the most powerful form of radioactive waves known in the universe.
How these mysterious waves are made, and where exactly they come from have baffled scientists for years, but scientists believe they are a sign for dark matter.
Scientists at Brown, Carnegie Mellon, and Cambridge universities have detected gamma ray emissions from the direction of the galaxy Reticulum 2. Bright areas indicate a strong gamma ray signal coming from the direction of the galaxy, according to the researchers' search algorithm
Dark matter is the missing substance that makes up to 80 per cent of the universe's mass. It has been described as 'the most important unsolved problems in modern physics.'
The galaxy, named Reticulum 2, was discovered within the past few weeks in the data of the Dark Energy Survey.
At 98,000 light-years from Earth, Reticulum 2 is one of the nearest dwarf galaxies yet detected
According to physicists at Carnegie Mellon, Brown and Cambridge universities, gamma rays coming from the direction of the galaxy are in excess of what would be expected from normal background.
'Something in the direction of this dwarf galaxy is emitting gamma rays,' said Alex Geringer-Sameth, a postdoctoral research associate at Carnegie Mellon University.
'There's no conventional reason this galaxy should be giving off gamma rays, so it's potentially a signal for dark matter,' said Alex Geringer-Sameth, a postdoctoral research associate in CMU's Department of Physics and the paper's lead author.
'In the search for dark matter, gamma rays from a dwarf galaxy have long been considered a very strong signature,' added Brown University's Savvas Koushiappas Koushiappas, an assistant professor of physics.
'It seems like we may now be detecting such a thing for the first time.'
The researchers caution that while these preliminary results are exciting, there's more work to be done to confirm a dark matter origin.
Scientists know that dark matter exists because it exerts gravitational effects on visible matter, which explains the observed rotation of galaxies and galaxy clusters as well as the fluctuations in the cosmic microwave background.
Dwarf galaxies are important in the hunt for the dark matter particle. They are thought to lack other gamma-ray-producing sources, so a gamma ray flux from a dwarf galaxy would make a very strong case for dark matter. Pictured is an artist's impression of the jet from a gamma-ray burst emerging at nearly light speed
'The gravitational detection of dark matter tells you very little about the particle behaviour of the dark matter,' said Matthew Walker, assistant professor of physics and a member of CMU's McWilliams Center for Cosmology.
'But now we may have a non-gravitational detection that shows dark matter behaving like a particle, which is a holy grail of sorts.'
A leading theory suggests that dark matter particles are WIMPs, or Weakly Interacting Massive Particles.
When pairs of WIMPs meet, they annihilate one another, giving off high-energy gamma rays.
If that's true, then there should be a lot of gamma rays emanating from places where WIMPs are thought to be plentiful, like the dense centres of galaxies.
The trouble is, the high-energy rays also originate from many other sources, including black holes and pulsars, which makes it difficult to untangle a dark matter signal from the background noise.
That's why dwarf galaxies are important in the hunt for the dark matter particle.
They are thought to lack other gamma-ray-producing sources, so a gamma ray flux from a dwarf galaxy would make a very strong case for dark matter.
'They're basically very clean and quiet systems,' Professor Koushiappas said.
Scientists have been looking at them for signs of gamma rays for the last several years using Nasa's Fermi Gamma-ray Space Telescope.
There's never been a convincing signal, until now.
Further study of this dwarf galaxy's attributes could reveal hidden sources that may be emitting gamma rays, but the researchers are cautiously optimistic.
'The fact that there are gamma rays and also a clump of dark matter in the same direction makes it quite interesting,' Professor Walker said.
Put the internet to work for you.
0 comments:
Post a Comment