Massive "Dark Halo" Discovered Beyond Edge of the Milky Way

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PostWed Dec 02, 2009 8:05 pm » by Savwafair2012

The biggest things in the universe just got bigger - or rather, they've always been bigger and we somehow missed it up to now. Supercomputer simulations of galactic core black holes indicate that instead of being a mere two billion times the mass of the sun, so insignificant you'd surely lose them if you sneezed, some could be as large as six billion suns -not including the "dark halo" that surrounds the Milky Way, which is more than ten times as much mass as all of the visible stars, gas, and dust in the rest of the galaxy.


The study by scientists at the Max Planck Institute for Extraterrestrial Studies (which couldn't sound smarter if it was Lex Luthor's university degree) focused on Messier 87, a particularly bright active galaxy in the Virgo cluster whose size, strong signals and proximity to Earth make it a common astronomical experimentation subject. Dr Karl Gebhart and colleagues ran a supercomputer simulation to calculate the mass of the monster at M87's core.

You need to simulate a black hole's size because there's no way to observe its mass directly - you can only infer its immensity by studying the effects on the mass around it (little things like entire galaxies). Where the new model differs from past efforts is its inclusion of the "dark halo", an unobservable ring of dark matter which astrophysicists now believe surround galaxies. Including something you can't see might sound like a great way to get any answer you like, but the simulation worked it out by observing the effects of this halo on the visible stars, then accounting for those calculated effects when simulating the black hole - which is why the program took several days to run on a computer that could probably calculate you to ten decimal places in one minute.

The dark matter halo is the single largest part of the Milky Way, covering the space between 100,000 light-years to 300,000 light-years from the galactic center. It is now believed that about 95% of the Galaxy is composed of dark matter, which does not seem to interact with the rest of the Galaxy's matter and energy in any way except through gravity. The dark matter halo is more than ten times as much mass as all of the visible stars, gas, and dust in the rest of the galaxy. While the luminous matter we see in the night skymakes up approximately 90,000,000,000 solar masses, he dark matter halo is believed to include around 600,000,000,000 to 3,000,000,000,000 solar masses of dark matter.

Don't worry, the results aren't entirely dependent on the dark matter magic-factor which affects so much of current cosmology - the results seem to explain observations which previously puzzled many scientists (always a good sign for a new result). Recordings of distant quasars show evidence of black holes far larger than anything we've ever seen closer to home. Now it seems that they were here all along, we just weren't looking at them right.

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PostWed Dec 02, 2009 9:07 pm » by Dirttyrabbit


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