Large-scale Structure in CHILES Using DisPerSE

Abstract

We demonstrate that the Discrete Persistent Source Extractor (DisPerSE) can be used with spectroscopic redshifts to define the cosmic web and its distance to galaxies in small-area deep fields. Here we analyze the use of DisPerSE to identify structure in observational data. We apply DisPerSE to the distribution of galaxies in the Cosmic Evolution Survey (COSMOS) field and find the best parameters to identify filaments. We compile a catalog of 11,500 spectroscopic redshifts from the Galaxy and Mass Assembly (GAMA) G10 data release. We analyze two-dimensional slices, extract filaments, and calculate the distance for each galaxy to its nearest filament. We find that redder and more massive galaxies are closer to filaments. To study the growth of galaxies across cosmic time, and environment, we are carrying out an H i survey covering redshifts of z = 0–0.45, the COSMOS H i Large Extragalactic Survey (CHILES). In addition we present the predicted H i mass fraction as a function of distance to filaments for the spectroscopically known galaxies in CHILES. Lastly we discuss the cold gas morphology of a few individual galaxies and their positions with respect to the cosmic web. The identification of the cosmic web, and the ability of CHILES to study the resolved neutral hydrogen morphologies and kinematics of galaxies, will allow future studies of the properties of neutral hydrogen in different cosmic web environments across the redshift range of z = 0.1–0.45.