A Study of Environmental Effects on Galaxy Spin Using MaNGA Data

TL;DR

This study analyzes how small-scale galaxy interactions, rather than large-scale environment, influence galaxy spin using MaNGA survey data of nearly 2800 galaxies.

Contribution

It provides new insights into the environmental dependence of galaxy spin, emphasizing the role of small-scale interactions over large-scale density effects.

Findings

Galaxy spin decreases with stellar mass in early-type galaxies.

Large-scale environment has little effect on galaxy spin.

Small-scale interactions significantly influence galaxy spin, especially for late-type galaxies.

Abstract

We investigate environmental effects on galaxy spin using the recent public data of MaNGA integral field spectroscopic survey containing ~2800 galaxies. We measure the spin parameter of 1830 galaxies through the analysis of two-dimensional stellar kinematic maps within the effective radii, and obtain their large- (background mass density from 20 nearby galaxies) and small-scale (distance to and morphology of the nearest neighbour galaxy) environmental parameters for 1529 and 1767 galaxies, respectively. We first examine the mass dependence of galaxy spin, and find that the spin parameter of early-type galaxies decreases with stellar mass at log (M$_*/$M$_{\odot}$) $\gtrsim$ 10, consistent with the results from previous studies. We then divide the galaxies into three subsamples using their stellar masses to minimize the mass effects on galaxy spin. The spin parameters of galaxies in each subsample do not change with background mass density, but do change with distance to and morphology of the nearest neighbour. In particular, the spin parameter of late-type galaxies decreases as early-type neighbours approach within the virial radius. These results suggest that the large-scale environments hardly affect the galaxy spin, but the small-scale environments such as hydrodynamic galaxy-galaxy interactions can play a substantial role in determining galaxy spin.