CHILES VI: HI and H${\alpha}$ Observations for z < 0.1 Galaxies; Probing HI Spin Alignment with Filaments in the Cosmic Web

TL;DR

This study combines HI and Hα observations of nearby galaxies to analyze their kinematics, morphology, and alignment with cosmic web filaments, revealing a tendency for galaxy spins to align with large-scale structures.

Contribution

It provides new observational evidence linking galaxy spin orientations to the cosmic web filaments at low redshift, using combined HI and Hα data.

Findings

Most galaxies follow known scaling relations despite irregularities.

HI and Hα velocities reach the flat rotation curve.

Galaxy spins tend to align with cosmic web filaments.

Abstract

We present neutral hydrogen (HI) and ionized hydrogen (H${\alpha}$) observations of ten galaxies out to a redshift of 0.1. The HI observations are from the first epoch (178 hours) of the COSMOS HI Large Extragalactic Survey (CHILES). Our sample is HI biased and consists of ten late-type galaxies with HI masses that range from $1.8\times10^{7}$ M$_{\odot}$ to $1.1\times10^{10}$ M$_{\odot}$. We find that although the majority of galaxies show irregularities in the morphology and kinematics, they generally follow the scaling relations found in larger samples. We find that the HI and H${\alpha}$ velocities reach the flat part of the rotation curve. We identify the large-scale structure in the nearby CHILES volume using DisPerSE with the spectroscopic catalog from SDSS. We explore the gaseous properties of the galaxies as a function of location in the cosmic web. We also compare the angular momentum vector (spin) of the galaxies to the orientation of the nearest cosmic web filament. Our results show that galaxy spins tend to be aligned with cosmic web filaments and show a hint of a transition mass associated with the spin angle alignment.