Saturday, July 28, 2007

Another Dark ... Matter

Addendum 2/16/2010:

Well again I am looking at Dark Matter. Well not exactly looking at it.

Here is a picture of NGC 4254. It is a beautiful spiral galaxy in the Virgo cluster. Notice its arm is pulled away from the galaxy. This is a question that has perplexed astronomers for years. Now it is understood.

The radio telescope of Arecibo Observatory, Cardiff University, Isaac Newton Telescope, and Westerbork Synthesis Radio Telescope have found a gas cloud of neutral Hydrogen and dark matter nearby. The finding of this cloud goes along way to understanding NGC 4254's outstretched arm.

Here is a picture of the area in the Virgo Cluster called VIRGOHI 21. Notice that the area is not visible. This is a Dark Matter Galaxy.

When we look at the area in the 21cm wavelength we see hydrogen gas jetting from NGC 4254 to VIRGOHI 21. In the third picture the Neutral hydrogen gas streams between NGC 4254 (top left) and the Dark Galaxy VIRGOHI 21 (center right) in this image made from radio telescope observations at a wavelength of 21 centimetres. This interaction could explain the mystery of NGC 4254's peculiar lopsided shape. To the bottom left, a ring of gas can be seen around the galaxy NGC 4262. This material was presented to the American Astronomical Society meeting in Washington, D. C. on January 12, 2006.

Even though Neutral Hydrogen is detected streaming into VIRGOHI 21, there is not enough hydrogen to cause the extension of the arm in NGC 4254. Something dense but dark is necessary to explain this. This is an example of Dark Matter.


CREDIT: Arecibo Observatory / Cardiff University / Westerbork Synthesis Radio Telescope.

Dark Matter - the other matter

We have known for some time that we were missing something. Every time we tried to model galaxy formation the stars would just fly apart. Then there was the problem that stars on the outer rims of galaxies moved at the same speed as those in denser regions.

For years now I have been contemplating the n-body problem. This problem is the model of Gravity. I noticed in my tea every morning that when I put the sugar in my tea and gave it a stir it would form the shape of a galaxy. The only way it could do this is if our models were missing the tea. Physicist also saw this problem, their galaxies were spinning out of control. Everything was in chaos. They were missing the tea too.

This picture is of the galactic cluster CL0024+17. Each point of light is a galaxy. Notice the dark ring. The amount of energy in the initial explosions caused a ripple in the dark matter. Visible matter is just a small part of the universe. Present estimates show the universe is made up of 22% Dark Matter, 74% Dark Energy, leaving only 4% of the universe made of light and normal matter.

What does this mean. We only understand ~4% of the universe. But with pictures like this we can start to understand the remaining 96%.

Picture, thanks to Hubble Space Telescope and to all the people who made this possible.
Addendum 5/16/2010