Forget dark matter! Scientists capture unprecedented images of DIM MATTER that connects galaxies throughout the universe
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Astronomers have been able to capture unprecedented images of a mysterious gas that connects galaxies throughout the universe.
Known as the intergalactic medium (IGM), this enigmatic substance has, up until now, merely been a matter of theoretical speculation.
But now Caltech scientists have used the Cosmic Web Imager (CWI) to obtain their first three-dimensional images of the IGM.
Astronomers have been able to capture unprecedented images of a mysterious gas that connects galaxies throughout the universe. Pictured is an image of quasar - a nucleus of a young galaxy - showing surrounding gas (in blue) and the direction of filamentary dim matter
WHAT IS DIM MATTER?
Dim matter is the mysterious gas that connects galaxies throughout the universe.
Since the late 1980s and early 1990s, theoreticians have predicted that primordial gas from the Big Bang is not spread uniformly throughout space.
Instead, it distributed in channels that span galaxies and flow between them.
This 'cosmic web'- the IGM - is a network of smaller and larger filaments crisscrossing one another across the vastness of space and back through time to an era when galaxies were first forming.
Of normal matter, only one-quarter is made up of stars and galaxies, the bright objects that light our night sky.
The remainder, which amounts to only about three per cent of everything in the universe, is the IGM.
The images could help astronomers better understand the structure of the cosmic web that flows through the universe to understand how it affects galaxies.
The IGM was imaged near two very bright objects; a quasar – which is the nucleus of a young galaxy - called QSO 1549+19, and something called a Lyman alpha blob – a huge concentration of a gas.
They found a single filament feeding into the quasar which was one million light-years long, and three filaments flowing into the Lyman alpha blob.
These filaments are estimated to have origins from approximately 2 billion years after the Big Bang.
The Cosmic Web Imager, used on the Hale telescope in California, was conceived and developed by Caltech professor of physics Christopher Martin.
'I've been thinking about the intergalactic medium since I was a graduate student,' he said.
'Not only does it comprise most of the normal matter in the universe, it is also the medium in which galaxies form and grow.'
Since the late 1980s and early 1990s, theoreticians have predicted that primordial gas from the Big Bang is not spread uniformly throughout space.
Instead, it distributed in channels that span galaxies and flow between them.
Dim matter was imaged near two very bright objects; a quasar ¿ which is the nucleus of a young galaxy - and something called a Lyman alpha blob ¿ a huge concentration of a gas. Pictured is a comparison of Lyman alpha blob observed with Cosmic Web Imager and a simulation of the cosmic web based on theoretical predictions
This 'cosmic web'- the IGM - is a network of smaller and larger filaments crisscrossing one another across the vastness of space and back through time to an era when galaxies were first forming.
Professor Martin describes the diffuse gas of the IGM as 'dim matter,' to distinguish it from the bright matter of stars and galaxies, as well as dark matter.
He explained that 96 per cent of the mass and energy in the universe is elusive dark energy and dark matter.
Scientists only know of it due to its effects on the remaining four per cent that we can see: normal matter.
Of this four per cent that is normal matter, only one-quarter is made up of stars and galaxies, the bright objects that light our night sky.
COSMIC 'FLASHLIGHT' ILLUMINATES DARK MATTER FOR THE FIRST TIME
Earlier this year, the mysterious strands of dark matter that hide beneath the visible universe were seen for the first time.
Dark matter is considered crucial to theories explaining how the universe is expanding and how galaxies interact, but has so far eluded scientists.
In January, astronomers produced the first direct images of a part of its network using a quasar as a 'flashlight'.
A quasar is a type of active galactic nucleus that emits intense radiation powered by a supermassive black hole at the centre of the galaxy.
This particular quasar, located 10 billion light-years away, illuminated a vast nebula of diffuse gas to reveal the network of filaments that connect galaxies in a cosmic web.
For years, cosmologists have been running computer simulations of the structure of the universe to develop what they refer to as the 'standard model of cosmology'.
Their calculations suggest that as the universe grows, matter becomes clustered like a huge cosmic web, weaving its way into in filaments and nodes under the force of gravity.
The results from the 10-metre Keck telescope in Hawaii, were reported by scientists from the University of California, Santa Cruz and the Max Planck Institute for Astronomy in Heidelberg.
Computer simulations suggest that matter in the universe is distributed in a 'cosmic web' of filaments, as seen in the image above from a large-scale dark-matter simulation. The inset is a zoomed-in, high-resolution image of a smaller part of the cosmic web, 10 million light-years across
The remainder, which amounts to only about three per cent of everything in the universe, is the IGM.
As the name suggests, 'dim matter' is hard to see. Matt Matuszewski, a former graduate student at Caltech likens it to trying to see a complex cityscape through a few narrow slits in a wall.
'All you would know is that there is some concrete, windows, metal, pavement, maybe an occasional flash of colour,' he said.
'Only by opening the slit can you see that there are buildings and skyscrapers and roads and bridges and cars and people walking the streets.
'Only by taking a picture can you understand how all these components fit together, and know that you are looking at a city.'
Professor Martin and his team have now seen the first glimpse of the city of dim matter. It is not full of skyscrapers and bridges, but it is both visually and scientifically exciting.
Dim matter was seen by the Cosmic Web Imager installed at the Palomar Observatory in California
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