Oral Presentation
A topological approach to galaxy distribution analysis
Presenter: Kai Kono (Nagoya University)
Large scale structure (LSS) of the Universe is the Mpc scale anisotropy in galaxy distribution made of various of topological structures such as clusters, filaments and voids. LSS is the result of evolution of initial fluctuation and as it holds information on initial perturbation field, it is often used for cosmological parameter constraints. Furthermore, since non-linear structure is mainly governed by galaxy physics, it is important to investigate the relation between LSS and galaxy properties.
In this study, we performed topological data analysis (TDA) to extract the topological information of LSS with SDSS DR14 (Ata et al. 2018). We especially evaluated persistent homology (PH). PH constructs filtration in respect to the increase of interest parameter. Then, we applied the PH to a quasar sample at $z<1.0$from extended Baryon Oscillation Spectroscopic Survey in Sloan Digital Sky Survey Data Release 14 (SDSS DR14). We constructed a cubic complete subsample of quasars with a volume of $1\ [{\rm Gpc^3}]$ and performed the PH. We discovered a characteristic hole (a hollow shell) at a scale $\sim150\ [{\rm Mpc}]$. This exactly corresponds to the BAO signature imprinted in the galaxy/quasar distribution. We performed this analysis on a small subsample of 2000 quasars. This clearly demonstrates that the PH analysis is very efficient in finding this type of topological structures even if the sampling is very sparse.
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