Galactic Cluster Suggests Hidden Superstructure

joncrie writes "The nearby galaxy cluster Fornax is facing an intergalactic headwind as it is pulled by an underlying superstructure of dark matter, according to new evidence from NASA's Chandra X-ray Observatory. Astronomers think most of the matter in the universe is concentrated in long large filaments of dark matter and that galaxy clusters are formed where these filaments intersect."

Comments

Filament = lensing?

[Fallen Andy]

Hmm. An on topic post at last (grins).
Dark matter in filaments implies gravitional lensing
Any news on that?

Re:Filament = lensing?

[rwllama]

No, dark matter in filaments does not have to imply lensing.

To get gravitational lensing, one has to have a sufficient integrated density along the line of sight. It is fair to surmise that looking "down the pipe" of a filament might produce enough integrated density to produce lensing, but it is not a necessary consequence.

I haven't heard of any lensing based on filament structures, but the folks who do what is called "weak lensing" might have some statistical arguments that can correlate their results with the likely (or unlikely) presence of filaments.

The main result I remember associated with filaments is the apparent clumpiness of the galaxy distribution on small scales. If you've got a lot of linear structures where galaxies form, then you get more super-positions of galaxies than would occur in a random distribution. Such arguments can explain the over-numerous of Hickson Compact Groups of Galaxies.

For those who would like to know what a "filament" might look like, you can see my visualization of large scale structure in the universe called "Cosmic Cruising 2" at http://terpsichore.stsci.edu/~summers/viz/cosmic_c ruising_2/. Please note that this visualization is not from observed galaxy data, but rather from a supercomputer simulation that has roughly the same statistical properties as the real universe.

Matrioshka Brains?

[mkcmkc]

Here's an obligatory link to Matrioshka Brains (a conceivable explanation for dark matter). If you haven't already seen this, you'll probably find it interesting.

Mike