Local Universe (APOD 11 Dec 2007)

[notaclone]

It kinda needs a "you are here ->" (or more eloquently "The Sun ->")

[Case]

It's a 2D map of a 3D sphere of the things around us in the sky. There is no "you are here" point on this map. Just like any star chart, just like any photo.

[BMAONE23]

the YOU ARE HERE point is the vantage point of the image.

[FreebirdsWB]

Still amazed at the "filaments" and other structures.

[iamlucky13]

Still amazed at the "filaments" and other structures.

I'm a little curious why most of the clusters form filaments instead of blobs. Does anyone know if this is a perspective issue, either from the sky survey or the projection, or if their actual structure tends to be filamentary? If the latter, why?

[BMAONE23]

It always reminds me of the structure of Brain Cells (Neurons)

[FreebirdsWB]

I saw something once that made the structures look like the walls of a pile of soap bubbles. Neurons is another good picture.

Think this was the site:
http://csep10.phys.utk.edu/astr162/lect ... /soap.html

[Nereid]

Still amazed at the "filaments" and other structures.

I'm a little curious why most of the clusters form filaments instead of blobs. Does anyone know if this is a perspective issue, either from the sky survey or the projection, or if their actual structure tends to be filamentary? If the latter, why?

It's an epiphenomenon of a 'General Relativity' universe in which cold dark matter dominates ordinary ('baryonic') matter by a factor of five or so - a conclusion from the Millennium Simulation (for example).

[starnut]

What are the dipoles in the upper right quandrant? I know CMB is cosmic microwave background and IRAS is Infra Red Astronomy Satellite.

[Nereid]

What are the dipoles in the upper right quandrant? I know CMB is cosmic microwave background and IRAS is Infra Red Astronomy Satellite.

An APOD on the CMB dipole.

IRAS dipole: when the sources detected by IRAS are analysed, many are found to be galaxies. If you select the sources which are galaxies carefully, to control for various statistical and observational effects, you find they are not distributed across the sky uniformly. From this distribution, you can estimate the 'local' gravitational field (out to a few hundred Mpc), which turns out to have a dipole component. The poles of this 'IRAS dipole' are close to the CMB dipole, but are not the same.

Here is the first paper on this (that I could find), dated 1986; and here is a 2000 one which reports "that the question of the origin of the CMB dipole is essentially resolved".

[kfsone]

Funny how the eye plays tricks. I was looking at the image for ages and suddenly George Washington's face popped out: The virgo cluster arrow pointing at top of his forehead, hercules supercluster pointing at the back of his hair, his neck stops at the milkyway; he's facing to the right side of the image. If you follow the line of the Coma Cluster arrow you'll run into a little filament of red dots, which forms his eyebrow.

What I was actually looking at when I saw it is the sort of "stripe" down the center of the image (coma and virgo cluster arrows end at the edges of it). Is that an artefact of how the data is collected?

One thing that's really puzzling me - as it has done in other images - is the prevalance of arched, almost eliptical or round, filaments: just left of the hercules supercluster arrows head, just past the centuarus arrow head, lots running along the opiuchus arrow line, and others big and small all over the image.

Are these artefacts of lensing?