Astronomers possibly find dark matter galaxy
Posted: Wed Feb 23, 2005 4:02 pm
http://news.bbc.co.uk/2/hi/uk_news/wales/s...ast/4288633.stm
Astronomers say they have discovered an object that appears to be an invisible galaxy made almost entirely of dark matter. The team, led by Cardiff University, claimed it is the first to be 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. It was found 50 million light years away using radio telescopes in Cheshire and Puerto Rico.
The unknown material that is thought to hold these dark galaxies together is known as 'dark matter', but scientists still know very little about what that is.
The five-year research has involved studying the distribution of hydrogen atoms throughout the Universe, estimated by looking at the rotation of galaxies and the speed at which their components moved.
Hydrogen gas releases radiation that can be detected at radio wavelengths. In the Virgo cluster of galaxies, they found a mass of hydrogen atoms a hundred million times the mass of the Sun. The mysterious galaxy has been called VIRGOHI21.
Similar objects that have previously been discovered have since turned out to contain stars or be remnants of two galaxies colliding. However, the scientists from the UK, France, Italy and Australia found no visible trace of any stars, and no galaxies nearby that would suggest a collision.
Dr Robert Minchin, of Cardiff University, said: "From its speed, we realised that VIRGOHI21 was a thousand times more massive than could be accounted for by the observed hydrogen atoms alone. "If it were an ordinary galaxy, then it should be quite bright and would be visible with a good amateur telescope."
The astronomers say it is hard to study the universe's dark, hidden objects because of the Earth's proximity to the Sun. They liken it to looking out at the darkest night from a well-lit room - it is easy to make out street lights but not trees, hedges and mountains.
Astronomers say it marks an important breakthrough because, according to cosmological models, dark matter is five times more abundant than the ordinary (baryonic) matter that makes up everything we can see and touch.
Another of the Cardiff team, Dr Jon Davies, added: "The Universe has all sorts of secrets still to reveal to us, but this shows that we are beginning to understand how to look at it in the right way. It's a really exciting discovery."
Archived topic from Anythingforums, old topic ID:1778, old post ID:24366
Astronomers say they have discovered an object that appears to be an invisible galaxy made almost entirely of dark matter. The team, led by Cardiff University, claimed it is the first to be 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. It was found 50 million light years away using radio telescopes in Cheshire and Puerto Rico.
The unknown material that is thought to hold these dark galaxies together is known as 'dark matter', but scientists still know very little about what that is.
The five-year research has involved studying the distribution of hydrogen atoms throughout the Universe, estimated by looking at the rotation of galaxies and the speed at which their components moved.
Hydrogen gas releases radiation that can be detected at radio wavelengths. In the Virgo cluster of galaxies, they found a mass of hydrogen atoms a hundred million times the mass of the Sun. The mysterious galaxy has been called VIRGOHI21.
Similar objects that have previously been discovered have since turned out to contain stars or be remnants of two galaxies colliding. However, the scientists from the UK, France, Italy and Australia found no visible trace of any stars, and no galaxies nearby that would suggest a collision.
Dr Robert Minchin, of Cardiff University, said: "From its speed, we realised that VIRGOHI21 was a thousand times more massive than could be accounted for by the observed hydrogen atoms alone. "If it were an ordinary galaxy, then it should be quite bright and would be visible with a good amateur telescope."
The astronomers say it is hard to study the universe's dark, hidden objects because of the Earth's proximity to the Sun. They liken it to looking out at the darkest night from a well-lit room - it is easy to make out street lights but not trees, hedges and mountains.
Astronomers say it marks an important breakthrough because, according to cosmological models, dark matter is five times more abundant than the ordinary (baryonic) matter that makes up everything we can see and touch.
Another of the Cardiff team, Dr Jon Davies, added: "The Universe has all sorts of secrets still to reveal to us, but this shows that we are beginning to understand how to look at it in the right way. It's a really exciting discovery."
Archived topic from Anythingforums, old topic ID:1778, old post ID:24366
One theory is that when the universe expands to the point where matter is spread out thin enough that dark matter is a greater force in the universe, the universe will start to implode in reverse fashion of the expansion until we end up at a singularity and the big bang happens again. We really have no way of knowing what happened before the big bang, it could be a cycle that has happened many times.