1. Visualisations of 6dF data by A.P. Fairall Using ‘Labyrinth’ software developed by Carl Hultquist and Samesham Perumal Departments of Astronomy and Computer Science University of Cape Town

2. An introduction to Labyrinth This software allows one to visualise a galaxy database from any chosen position, looking in any chosen direction. One can also interactively fly around the database (although the presentation here uses still frames).

3. Lets start by looking at some (non-6dF) data with the galaxies Represented as white points

4. The readouts in the lower left corner give direction of view and position in Cartesian Supergalactic coordinates

5. Labels can be turned on to identify features

6. Colour coding can be introduced to represent distance. Nearest galaxies red, distant galaxies blue

7. This enables a steroscopic view of the distribution using ChromoDepth™ spectacles

8. But instead of this distracting false colour…

9. ..we change the coding to white (near) to blue (far), which works with or without spectacles

10. Labyrinth also lets us fade background structures…

15. Now we see only the nearest galaxies, which can also be shown..

16. ..as billboards, with images to scale, so giving a realistic visualisation of extragalactic space.

24. But the main purpose of Labyrinth is to grow “Tully bubbles” around groups and clusters of galaxies

25. This is 6dF data!

29. The bubbles can be made completely opaque

30. The individual galaxies need not be shown

31. The Software identifies Minimal Spanning Trees (MSTs) and wraps a surface around them. A minimum number of galaxies per MST can be specified

32. The MSTs are specified by a percolation radius (r) At cz = 0 To compensate for the diminishing density of data with increasing redshift, the percolation radius is increased with incresing cz. In this way the average density of bubbles stays more or less constant with increasing distance

33. As the bubbles grow, they interconnect to reveal the web of large-scale structures

34. Now to 6dF! We begin by taking 6dF data with cz < 7500 km/s so to examine very nearby large-scale structures.

35. The view is looking back from a point at cz = 20000 km/s in the direction of the North Celestial Pole

36. Northern Galactic Hemisphere at top Southern Galactic Hemisphere at bottom

37. Now to switch on the colour coding

38. True stereoscopy can be obtained by viewing these images With ChromoDepth spectacles

39. Individual galaxies

40. Mimimal spanning trees show the densest regions in the data

41. The percolation distance r is set at 5 km/s

42. The minimum number of galaxies per MST is set at 10

43. As we increase the percolation distance, so the structures grow. Here it is r = 10 km/s

44. r = 20 km/s

45. r = 30 km/s

46. r = 40 km/s

47. r = 50 km/s

48. r = 60 km/s

49. r = 70 km/s

50. r = 80 km/s Much more Detail can be Seen than was Previously possible

51. r = 90 km/s

52. r = 100 km/s

53. r = 120 km/s

54. r = 140 km/s

55. r = 160 km/s

56. r = 180 km/s

57. r = 200 km/s

58. But let’s go back..

63. .. to r = 100 km/s

64. Various features can be identified

65. We can also blur the large-scale structures

66. And gradually bring back the individual galaxies

71. Galaxies and Large-scale structures

72. Now let’s bring in the complete 6dF data

78. r = 5 km/s Once again MSTs show the densest regions

79. r = 10 km/s

80. r = 20 km/s

81. r = 30 km/s

82. r = 40 km/s

83. r = 50 km/s

84. r = 60 km/s

85. r = 70 km/s

86. r = 80 km/s

87. r = 90 km/s

88. r = 100 km/s 6dF reveals texture more detailed than ever before seen

89. r = 110 km/s

90. r = 120 km/s

91. r = 130 km/s

92. r = 140 km/s

93. r = 150 km/s

94. r = 175 km/s

95. r = 200 km/s

96. r = 300 km/s

97. r = 400 km/s

98. r = 500 km/s

99. r = 600 km/s

100. We can also constrain how the percolation radius varies with redshift

101. 100 k/s And thereby find groups and clusters (rather than large-scale structures)

102. 75 km/s Decreasing the percolation finds the denser clusters

103. 50 km/s

104. 40 km/s For example, Labyrinth finds and list just over 100 clusters here. About two-thirds of them are Abell clusters

105. But work is still in progress! Thanks to Matthew Colless, Heath Jones and Lachlan Campbell for access to the 6dF data