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Viewing densities of galaxy positions
http://forum.celestialmatters.org/viewtopic.php?f=4&t=906
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Author:  Selden [ Tue, 30-05-17, 11:50 GMT ]
Post subject:  Viewing densities of galaxy positions

Here's my most recent attempt to reproduce the SDSS image Orange Pie, using Celestia to view the results. (I did something similar a long time ago using DR2.) The range in Z values is somewhat larger than the SDSS image, although the outermost whole green circle corresponds to the outer limit of theirs. Coloration is strictly by density, going from red for the least dense through yellow to white at the most dense.

I used http://skyserver.sdss.org/Casjobs to select galaxies in the appropriate RA and Dec ranges from the most recent SDSS data release, DR13, although I think they've only improved the processing of the data provided in DR7, not added anything new. The lower fan in the picture is "Stripe 82", the one which is used by the "Galaxy Zoo" project.

A Celestia "Addon" can be made available in a few days which includes this and some additional "fans" if anyone is interested.

Attachments:
File comment: entire dataset
sdss_pie2_entire.jpg
sdss_pie2_entire.jpg [ 198.97 KiB | Viewed 414 times ]
File comment: "orange pie" in celestia
sdss_pie2.jpg
sdss_pie2.jpg [ 228.43 KiB | Viewed 414 times ]

Author:  t00fri [ Tue, 30-05-17, 13:19 GMT ]
Post subject:  Re: Viewing densities of galaxy positions

Nice, Selden.

Notably in your lower plot the large-scale galactic filiaments are nicely visible. They are objects of major interest in cosmological research.
Here is a selection of fliament plots from Google.
https://www.google.de/search?q=galactic ... 2&bih=1131
Most data in these images are actually from the gigantic "Millenium" simulation by means of SuperComputers.
See also our discussions at CM:
viewtopic.php?f=7&t=258
Around 2008 and again in 2015 (with SDSS_Dr6 data) I did a lot of respective galaxy plots/scripts in the context of implementing a "cosmological workflow" in celestia.Sci. Unfortunately, we are massively behind schedule, here. But I will certainly return to these fascinating and very fundamental large-scale structures in the Universe...

Cheers,
Fridger

Author:  Selden [ Tue, 30-05-17, 13:55 GMT ]
Post subject:  Re: Viewing densities of galaxy positions

Thanks for the link!

My selection criteria were much more simplistic and need to be improved.

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