科研之友
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摘要
The recent progress in obtaining larger and deeper galaxy catalogues is of fundamental importance for cosmological studies, especially to robustly measure the large-scale density fluctuations in the Universe. The present work uses the Minkowski Functionals (MF) to probe the galaxy density field from the WISExSuperCOSMOS (WSC) all-sky catalogue by performing tomographic local analyses in five redshift shells (of thickness delta z = 0.05) in the total range of 0.10 < z< 0.35. Here, for the first time, the MF are applied to 2D projections of the galaxy number count (GNC) fields with the purpose of looking for regions in the WSC catalogue with unexpected features compared to Lambda CDM mock realizations. Our methodology reveals one to three regions of the GNC maps in each redshift shell with an uncommon behaviour (extreme regions), i.e. p-value < 1.4 per cent. Indeed, the resulting MF curves show signatures that suggest the uncommon behaviour to be associated with the presence of over-or underdensities there, but contamination due to residual foregrounds is not discarded. Additionally, even though our analyses indicate a good agreement among data and simulations, we identify one highly extreme region, seemingly associated with a large clustered distribution of galaxies. Our results confirm the usefulness of the MF to analyse GNC maps from photometric galaxy data sets.
- 出版日期2018-8
