Millennium simulation in Celestia

[Cham]

Here's a cube of 3000 Mpc on each side in Celestia, containing 1.6 millions of particles. Each particle is an entire galaxy cluster. I'm very surprised that it runs extremely smoothly in Celestia, on the crappy computer in my office !

3000Mpc.jpg

Moving inside is simply incridible ! Talk about a thick fog of galaxies !

This is a simulation of the Universe today, from this site :

http://www.mpa-garching.mpg.de/Virgo/

[ElChristou]

How much? 500 Mo?

[Cham]

How much? 500 Mo?

Nope. 41.2 MB, in ASCII format, unzipped.

[ElChristou]

Grrr... still haven't find any server?

[Cham]

Grrr... still haven't find any server?

Not yet. Don't have much time...

[Vincent]

Here's a cube of 3000 Mpc on each side in Celestia, containing 1.6 millions of particles. Each particle is an entire galaxy cluster. I'm very surprised that it runs extremely smoothly in Celestia, on the crappy computer in my office !

Martin,

That's fabulous !

Nope. 41.2 MB, in ASCII format, unzipped.

Would it be possible for you to split it into smaller files ?
I'm really looking forward to test this on my machine.

[Cham]

Would it be possible for you to split it into smaller files ?
I'm really looking forward to test this on my machine.

Since the whole cube is too foggy, I intend to make some thin blades from it. Maybe a pie shaped version, as a SLOAN like model. I need to experiment a lot with the data, since it isn't obvious how to manipulate the huge data files from the source. The last cube I presented above is just experimental. Expect more models during the following weeks.

EDIT : The cubical shape isn't ideal at this scale, since we see some edges effects from inside the cube. A slice would be much preferable. This would also reduce the file size alot!

[Cham]

A blade like this one is much more interesting :

blade.jpg

It's fun to see how much we could fill Celestia's space (longest size of this rectangle is 3000 Mpc !)

[Cham]

This morning, I made a nice "thin" blade. The square has a lenght of 13.4 GLY (almost the max allowed in Celestia!). Each dot is a galactic CLUSTER (not a galaxy). There's a total of about 50000 dots in this model and the ASCII CMOD file is just 1.2 MB.

Some views :

blade1.jpg

The small cube visible in the middle is my previous (final) addon from the Millenium database :

blade3.jpg

A view with my cosmological grid activated :

blade2.jpg

[ElChristou]

...and the ASCII CMOD file is just 1.2 MB.

Mail?

[Cham]

Here's a sprites version of my previous model. It's nice in Celestia, on my machine, but apparently sprites aren't working the same on other machines (buggy)... DARN%$#*& !

test.jpg

sprites.jpg

[Cham]

To Chris, Fridger and Andrew :

The source I'm using is giving the number of particles (galaxies) in each group (cluster). So each dot in my model should have a sprite size proportional to this number. Ideally, how should I define the sprite size with this number of members in a given group ?

The sprite size is currently constant on the previous pictures, and gives a nice rendering in Celestia. But I can easily modulate that size, using the MIN and MAX values of the number of members in the groups.

[t00fri]

Here's a sprites version of my previous model. It's nice in Celestia, on my machine, but apparently sprites aren't working the same on other machines (buggy)... DARN%$#*& !

test.jpg

sprites.jpg

I have a problem here: I don't see much of the famous large scale filiaments, that are so conspicuous in the original simulation and in "everybody's" mind

http://www.mpa-garching.mpg.de/galform/ ... u_fast.avi

You sprite patterns look more like a uniform random distribution...

Fridger

[Cham]

Fridger,

the scale on your video and the model I've shown isn't the same. My previous model is at the 3000Mpc scale, so yes, matter is almost homogeneous. However, moving around it do shows many bubbles and structures.

Your video is also showing individual galaxies, which isn't the case of my previous model (clusters only, or else the model would be huge on disk and slow in Celestia).

[t00fri]

Fridger,

the scale on your video and the model I've shown isn't the same. My previous model is at the 3000Mpc scale, so yes, matter is almost homogeneous. However, moving around it do shows many bubbles and structures.

Your video is also showing individual galaxies, which isn't the case of my previous model (clusters only, or else the model would be huge on disk and slow in Celestia).

But whatever the add-on, if the large scale filiaments cannot be conspicuously seen, the add-on's purpose is rather obsolete. The filiaments are the most exciting feature! Their Fourier transform encodes the precise value of the spectral index that in turn determines the underlying cosmology (ns<1?, ns=1?, ns>1?) !

Fridger

[Cham]

Fridger, we DO see bubbles, voids and filaments in my model. The sprites are making them more obvious, while the observer is moving around.

The MIN number of galaxies in each group is 30. The MAX number is 1564, and the average is 71.72, on a total number of 50849 clusters in the blade model. The VARIANCE is 39.32. Now, I need to define the sprite sizes according to this statistic. What would be the best formula ? If N is the number of galaxies in a given groupe, then :

SpriteSize(N) = ??

[Cham]

I've build another version of the previous model, with sprites of variable size. The size is defined by a constant volumic density of galaxies inside the clusters. The rendering is more satisfying in Celestia :

sprites.jpg

[Cham]

Here's a complete cube from the VIRGO simulation. Too heavy for Celestia (ASCII CMOD file of 52.9 MB, and 1.6 millions of sprites of variable size) :

cube1.jpg

cube2.jpg

There are some edges effects which are annoying.

View from the inside, close to the Milky Way :

interieur.jpg

[ElChristou]

What if you reduce the sprites size? actually the view is too cluttered...

[Cham]

What if you reduce the sprites size? actually the view is too cluttered...

Well, even with dots only (no sprites), it's too cluttered. And the CMOD file is too large anyway. Only a smaller cube or some blades are acceptable. A smaller cube will lose too much of the large scale structures, so only the blades are interesting. I'm building a thick blade right now.