Visualisations of MSPM Groups, Clusters, Filaments and Voids

Anthony G. Smith, Andrew M. Hopkins, Richard W. Hunstead and Kevin A. Pimbblet

Below are animated spins of 20 groups and clusters, 53 filaments and 47 voids, identified in SDSS DR7 data by MSPM. A box that encompasses the rumoured scale of statistical homogeneity is shown on this page. For each field, three modes of visualisation have been produced: particle plots that show the raw galaxy distribution, isosurfaces based on the smoothed galaxy density field and solid particle renders. Try not to lose sight of how huge these are!**


Three modes of visualisation of MSPM filament 1063, from the same viewing angle. Left: The galaxy distribution, with galaxies as black markers. Centre: The filament as a contiguous structure. The raw galaxy distribution has been smoothed in three dimensions with a Gaussian filter. The surfaces shown follow contours of twice the mean density. Right: A solid particle render with individual galaxies plotted as spoked white dots with radii of 0.125 Mpc/h. MSPM groups and clusters are Gaussian blurs with various properties colour-coded***.

These .gif files are each a few megabytes.

Groups and Clusters
Groups and clusters from Table 1 of our paper. These have transverse side lengths of 8 Mpc/h and contain a redshift interval (shown vertically) of Δz = 0.01 (~ 28 Mpc/h) to contain galaxies displaced by radial motions. Isosurfaces are based on three-dimensional gaussian smoothing with σ = 1 Mpc/h.

ID Particle Isosurface Solid Particle Render
1
2
3
4
5
6
7
8
9
10
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000

Filaments
Filaments from Table 5 of our paper. These cubes have transverse side lengths of 20 Mpc/h and line-of-sight lengths of Δz = 0.01 (~ 28 Mpc/h) to contain galaxies displaced by radial motions. Isosurfaces are based on three-dimensional gaussian smoothing with σ = 1 Mpc/h.

ID Particle Isosurface Solid Particle Render
68
84
299
404
663
1063
1082
1088
1494
1511
1541
1946
2088
2547
2770
2937
3086
3094
3305
3502
3656
3750
3861
4074
4604
4647
4885
4976
5021
5149
5381
5527
5745
5832
5853
5935
5972
5984
6007
6252
6280
6574
6656
6695
6760
6846
6858
6920
7039
7642
8048
8555
9625

Voids
These cubes have side lengths of 80 Mpc/h. ID numbers simply refer to positions in a lattice used to sample the SDSS volume. Isosurfaces are based on three-dimensional gaussian smoothing with σ = 5 Mpc/h. A box that encompasses the rumoured scale of statistical homogeneity is shown on this page.

ID Particle Isosurface Solid Particle Render
16110
22406
26786
30110
33619
33952
35795
36559
38881
39279
40506
40699
42116
42939
43788
44807
45996
46586
46675
46685
47728
47835
48026
48146
48209
48554
48603
48912
49082
49316
49549
49796
50023
50041
51144
51452
52731
53043
53747
53786
53954
54550
55015
55169
55366
55716
55822

The animated gifs were encoded by images2gif from python's visvis library.

***In solid particle renders, MSPM groups and clusters are Gaussian blurs with various properties colour-coded. Overdensity probabilities between 0.5 and 1 are mapped to blue values between 0 and 1, and this is also the intensity of each group. Radius is red such that a ~ 1 Mpc/h structure has a red value of one and a 0.5 Mpc/h structure has a red value of 0.5, etc. The radius (σ) of the Gaussian blur is the radius of the structure. Elongation values used for the green colours are averages of the five values obtained within 10 Mpc/h. The actual elongation probabilities calculated for our paper are maximum values that are the same for many adjacent groups and not as visually interesting to use.

**Somewhat related (from xkcd) -

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