Response to Comment on "Long-Lived Giant Number Fluctuations in a Swarming Granular Nematic"

doi:10.1126/science.1154685

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Response to Comment on "Long-Lived Giant Number Fluctuations in a Swarming Granular Nematic"

V. Narayan¹, S. Ramaswamy¹ and N. Menon²^*

¹ Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India.
² Department of Physics, University of Massachusetts, Amherst, MA 01003, USA.

Fig. 1. Coarse-grained density maps in active granular rods. (A) Red and blue symbols indicate the location of maximum and minimum time-averaged density, respectively, in 12 different realizations of the experiment at varying densities and excitation strengths. In each case, the duration of the experiment was 45 min and the vibration frequency was 200 Hz. (B) For each realization of the experiment (rows correspond to N = 1500, 2000, 2520, and 2800, and columns to dimensionless acceleration of ${Gamma}$ = 5, 6, 7), we show in each coarse-grained element the highest density achieved at that location during the run. There are multiple local maxima and minima distributed around the cell, showing that the density fluctuations are very mobile. [View Larger Version of this Image (70K GIF file)]

Fig. 2. Density autocorrelations showing clear logarithmic behavior in the giant number fluctuation regime (N = 2820) but not at lower particle density (N = 800, 1500). [View Larger Version of this Image (19K GIF file)]