Project

General

Profile

SG-G6, SG-G7

Check for significant spatial inhomogeneities in the galaxy density distribution of the flux-limited sample (SG-G6) and in photo-z bins (SG-G7). Note that this can incorporate tests GAL-G9 and GAL-G10.

Prerequisites

At least one field with 4 deg on a side to full depth in each band (as required by R-30). Comparison to combination of COSMOS field to reach the faint end, southern VVDS fields, and Guide Star Catalog II to reach requested area (but only at J < 21.5)

Procedure

For each scale s (0.05 sq.deg to 4 sq.deg.), producing N_s subareas, each of which will have N_s_i true galaxies and DeltaN_s_i objects classified as galaxies which have no correspondence in the external data set (artifacts, badly classified stars or quasars) :

1. Calculate mean density rho_s = sum(N_s_i)/N_s. We are factoring out the area because we will finally measure fluctuations. We are assuming that the contamination levels fluctuate randomly with ~0 bias (so rho_true_galaxies ~= rho_measured_galaxies, TBC).

2. Calculate Delta = 2/N * sqrt(sum((N_s_i-rho_s)*DeltaN_s_i))

3. Calculate PFC = |Delta-rho|/rho

In test SG-G7: divide area into redshift bins.

Verdict

SG-G6: PFC < 0.02 (for the flux limited sample)
SG-G7: PFC < 0.05 (in photo-z slices)

Tools: python script. Already exists for DC testing but will require revision and adaptation.

Consequences

Check inhomogeneities of only stars or other identified objects, to check whether the problem is from image artifacts, trails; compare with DC6B analysis