CommentsAccepted to ApJ (March 10, 2013, V765-2). Partial correlation analysis and a brief comparison with the model of Bromberg, Nakar, Piran & Sari (2012) (http://arxiv.org/abs/1210.0068) were included upon referee request
Journal refThe Astrophysical Journal, 766:111 (22pp), 2013 April 1
Comments10 pages, 7 figures, improved, extended in sections IV, V, more discussions to clarify some issues, references added, typos corrected. Accepted in GERG
Comments7 pages in LaTeX with the PTP style. No figure. To be published in the proceedings of the workshop "Braneworld -- Dynamics of spacetime with boundary --"