Comment on the paper by L. Guzzo "Is the Universe homogeneous ?"

Abstract

This comment is in response to the paper by L. Guzzo recently appeared in ``New Astronomy'' related to our work. The subject of the discussion concerns the correlation properties of galaxy distribution in the available 3-d samples. There is a general agreement that galaxy structures exhibit fractal properties, at least up to some scale. However the presence of an eventual crossover towards homogenization, as well as the exact value of the fractal dimension, are still matter of debate. Here we briefly summarize our point of view by discussing three main topics. The first one is methodological, i.e. we clarify which are the correct methods to detect the real correlations properties of the 3-d galaxy distribution. Then we discuss the results of the analysis of several samples in two ranges of scales. In the first range of scale, below $100 \div 200 \hmp$, the statistical quality of the data is rather good, and we find that galaxy distribution has fractal properties with $D \approx2$. At larger distances the statistical robustness of the present data is weaker, but, we show that there is evidence for a continuation of the fractal behavior, without any tendency towards homogenization.