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First Invisible Galaxy Discovered in Cosmology Breakthrough
SPACE.com ^ | February 23, 2005 | Robert Roy Britt

Posted on 02/23/2005 4:11:58 PM PST by AntiGuv

Astronomers have discovered an invisible galaxy that could be the first of many that will help unravel one of the universe's greatest mysteries.

The object appears to be made mostly of "dark matter," material of an unknown nature that can't be seen.

   Images

The ellipse shows the region of sky where the dark galaxy was found. Credit: Cardiff University/Isaac Newton Telescope on La Palma

NGC 7479 is the type of galaxy astronomers would have expected to see based on the measurements taken. Credit: Nik Szymanek/Faulkes Telescope North, Maui, copyright FTLLC
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Theorists have long said most of the universe is made of dark matter. Its presence is required to explain the extra gravitational force that is observed to hold regular galaxies together and that also binds large clusters of galaxies.

Theorists also believe knots of dark matter were integral to the formation of the first stars and galaxies. In the early universe, dark matter condensed like water droplets on a spider web, the thinking goes. Regular matter -- mostly hydrogen gas -- was gravitationally attracted to a dark matter knot, and when the density became great enough, a star would form, marking the birth of a galaxy.

The theory suggests that pockets of pure dark matter ought to remain sprinkled across the cosmos. In 2001, a team led by Neil Trentham of the University of Cambridge predicted the presence of entire dark galaxies.

One of perhaps many

The newfound dark galaxy was detected with radio telescopes. Similar objects could be very common or very rare, said Robert Minchin of Cardiff University in the UK.

"If they are the missing dark matter halos predicted by galaxy formation simulations but not found in optical surveys, then there could be more dark galaxies than ordinary ones," Minchin told SPACE.com.

In a cluster of galaxies known as Virgo, some 50 million light-years away, Minchin and colleagues looked for radio-wavelength radiation coming from hydrogen gas. They found a well of it that contains a hundred million times the mass of the Sun. It is now named VIRGOHI21.

The well of material rotates too quickly to be explained by the observed amount of gas. Something else must serve as gravitational glue.

"From the speed it is spinning, we realized that VIRGOHI21 was a thousand times more massive than could be accounted for by the observed hydrogen atoms alone," Minchin said. "If it were an ordinary galaxy, then it should be quite bright and would be visible with a good amateur telescope."

The ratio of dark matter to regular matter is at least 500-to-1, which is higher than I would expect in an ordinary galaxy," Minchin said. "However, it is very hard to know what to expect with such a unique object -- it may be that high ratios like this are necessary to keep the gas from collapsing to form stars."

Long road to discovery

Other potential dark galaxies have been found previously, but closer observations revealed stars in the mix. Intense visible-light observations reveal no stars in VIRGOHI21.

The invisible galaxy is thought to lack stars because its density is not high enough to trigger star birth, the astronomers said.

The discovery was made in 2000 with the University of Manchester's Lovell Telescope, and the astronomers have worked since then to verify the work. It was announced today. "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," said astronomer Jon Davies of Cardiff University in the UK. It's a really exciting discovery."

Additional radio observations were made with the Arecibo Observatory in Puerto Rico. Follow-up optical work was done with the Isaac Newton Telescope in La Palma. Astronomers from the UK, France, Italy and Australia contributed to the research. The project is now searching for other possible dark galaxies.

Dark matter makes up about 23 percent of the universe's mass-energy budget. Normal matter, the stuff of stars, planets and people, contributes just 4 percent. The rest of the universe is driven by an even more mysterious thing called dark energy.


TOPICS: Miscellaneous; News/Current Events
KEYWORDS: astronomy; cosmology; darkmatter; space
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1 posted on 02/23/2005 4:11:59 PM PST by AntiGuv
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To: PatrickHenry

shady ping!


2 posted on 02/23/2005 4:13:10 PM PST by AntiGuv (™)
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To: AntiGuv

A most significant discovery.


3 posted on 02/23/2005 4:17:24 PM PST by facedown (Armed in the Heartland)
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To: AntiGuv

Dark matter, dark energy - stay away from the dark side!


4 posted on 02/23/2005 4:21:17 PM PST by Wneighbor
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To: AntiGuv

What part of "invisible" did I miss?

Are they now visible.


5 posted on 02/23/2005 4:24:01 PM PST by edcoil (Reality doesn't say much - doesn't need too)
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To: lonevoice

Paging Art Bell . . .


6 posted on 02/23/2005 4:27:47 PM PST by Pride in the USA
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To: AntiGuv
I still think the dark matter is 'fudge'. Were there any theories that called for it before cosmologists found out there wasn't enough 'regular' matter to make their then-current theories go?
7 posted on 02/23/2005 4:28:00 PM PST by Grut
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To: facedown

Maybe they discovered Heaven. I just wonder if it is a physical place that can be discovered. Maybe the dark matter is in a different dimension or something. The advances by astronomers in the past 30 years or so is just amazing.


8 posted on 02/23/2005 4:28:21 PM PST by mlc9852
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To: Pride in the USA; Art Bell

Good idea. Ping!


9 posted on 02/23/2005 4:31:11 PM PST by lonevoice (Vast Right Wing Pajama Party)
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To: lonevoice

I knew about thse galaxies long ago, and kept pointing them out to people; but they said I was nuts.


10 posted on 02/23/2005 4:37:10 PM PST by Loud Mime (Silence from the masses satisfies the tyrants....get involved!)
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To: AntiGuv

So if you were on a planet in this dark galaxy, would it suck your tan off of you?


11 posted on 02/23/2005 4:42:00 PM PST by steveo (Member: Fathers Against Rude Television)
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To: AntiGuv
Close up picture of this pheonemenon:


12 posted on 02/23/2005 4:45:27 PM PST by freedumb2003 (If you oppose jihad, you are not a Muslim. If you support jihad, you are my enemy.)
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To: AntiGuv

Duplicate post:

http://www.freerepublic.com/focus/f-news/1349621/posts?page=32#32

My reply on that thread was that they had discovered an invisible galaxy (right!) but couldn't invent calorie free cheesecake? Wassup?


13 posted on 02/23/2005 4:46:31 PM PST by bill1952 ("All that we do is done with an eye towards something else.")
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To: AntiGuv
Astronomers have discovered an invisible galaxy that could be the first of many that will help unravel one of the universe's greatest mysteries. The object appears to be made mostly of "dark matter," material of an unknown nature that can't be seen.

Are they sure? Maybe they just forgot to take the lens cap off of their telescope.

14 posted on 02/23/2005 4:49:03 PM PST by GreenHornet
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To: Grut
Were there any theories that called for it before cosmologists found out there wasn't enough 'regular' matter to make their then-current theories go?

Probably not, but that is an integral part of the definition of a theory. Observations show that objects are behaving differently than, in this case, known (and to a large extent proven) physics can can describe. The result is either the known physics (in this case basic gravity) is wrong, or something else with currently unobservable mass is in play in the observations.

This theory relies on well known laws of gravitational attraction, but observations said there ain't enough mass to do what has been repeatedly observed. So either apples fall up in some places, or there is more mass than what can be observed. The theory is that there is more mass than could be observed.

Now, through new methods, inferences, or whatever (I'm not a cosmologist, astrophysicist, or even very cosmopolitan) researchers think they have "seen" dark matter.

These results support the theory. If they had been different, they could have forced a change in the theory.

And, that's what it's all about..

15 posted on 02/23/2005 4:49:49 PM PST by !1776!
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To: AntiGuv

WOW! They found Hillary's brain!!


16 posted on 02/23/2005 4:50:28 PM PST by Fledermaus (I Googled "Democrat+Sane" and got no hits.)
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To: VadeRetro; Junior; longshadow; RadioAstronomer; Doctor Stochastic; js1138; Shryke; RightWhale; ...
Science Ping! An elite subset of the Evolution list.
See list's description in my freeper homepage. Then FReepmail to be added/dropped.

17 posted on 02/23/2005 4:51:48 PM PST by PatrickHenry (<-- Click on my name. The List-O-Links for evolution threads is at my freeper homepage.)
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To: bill1952

Opps! I searched for it but didn't come up with anything. It's a different version of the news, however, so I guess it's alright.


18 posted on 02/23/2005 4:52:27 PM PST by AntiGuv (™)
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To: AntiGuv
Dark Matter . . pffft yea right.
I'll believe it when I see it.
19 posted on 02/23/2005 4:53:51 PM PST by ChadGore (VISUALIZE 62,041,268 Bush fans.)
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To: AntiGuv

If it's not recorded in the Jedi library catalog, it doesn't exist.


20 posted on 02/23/2005 4:55:43 PM PST by js1138
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