Detection from an astronomical survey

The CfA redshift catalogue contains the coordinates of 18,000 galaxies covering a part of the Universe. From this catalogue a thin slice of the universe of about 1000 galaxies was extracted, with a right ascension between 8 and 17 hours, a declination between 26.5 and 32.5 degrees and a recession velocity lower than 15000 km.s. The spatial distribution of this subset of galaxies is plotted in Figure 6. The result of the extraction with the ``Quality Candy'' model shows a very interesting filament network. One can recognize the famous ``Great Wall'' filament crossing the whole catalogue as well as the circular filaments surrounding void regions.

Figure 6: Extracted filament network from a galaxy map of the CfA catalogue.