Galaxy distribution and extreme-value statisticsT. Antal1, F. Sylos Labini2, 3, N. L. Vasilyev4 and Y. V. Baryshev4
1 Program for Evolutionary Dynamics, Harvard University - Cambridge, MA 02138, USA
2 Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi - Piazzale del Viminale 1, 00184 Rome, Italy, EU
3 Istituto dei Sistemi Complessi CNR - Via dei Taurini 19, 00185 Rome, Italy, EU
4 Institute of Astronomy, St. Petersburg State University - Staryj Peterhoff, 198504, St. Petersburg, Russia
received 23 August 2009; accepted in final form 12 November 2009; published December 2009
published online 11 December 2009
We consider the conditional galaxy density around each galaxy, and study its fluctuations in the newest samples of the Sloan Digital Sky Survey Data Release 7. Over a large range of scales, both the average conditional density and its variance show a non-trivial scaling behavior, which resembles criticality. The density depends, for 10 r 80 Mpc/h, only weakly (logarithmically) on the system size. Correspondingly, we find that the density fluctuations follow the Gumbel distribution of extreme-value statistics. This distribution is clearly distinguishable from a Gaussian distribution, which would arise for a homogeneous spatial galaxy configuration. We also point out similarities between the galaxy distribution and critical systems of statistical physics.
98.80.-k - Cosmology.
05.40.-a - Fluctuations phenomena, random processes, noise, and Brownian motion.
02.50.-r - Probability theory, stochastic processes, and statistics.
© EPLA 2009