The RINGS Survey: High-Resolution H-alpha Velocity Fields of Nearby Spiral Galaxies with the SALT Fabry-Perot

TL;DR

This paper presents high-resolution H-alpha velocity fields of nearby spiral galaxies obtained with SALT Fabry-Perot, demonstrating their consistency with previous data and exploring localized velocity discrepancies.

Contribution

It introduces high-resolution spectrophotometric data of spiral galaxies using SALT Fabry-Perot and compares these with existing HI data to analyze velocity differences.

Findings

High-resolution H-alpha velocity fields match previous measurements.

Small regions show significant velocity differences between H-alpha and HI.

Possible explanations for velocity discrepancies are discussed.

Abstract

We have obtained high-spatial-resolution spectrophotometric data on several nearby spiral galaxies with the Southern African Large Telescope (SALT) Fabry-P\'erot interferometer on the Robert Stobie Spectrograph (RSS) as a part of the RSS Imaging spectroscopy Nearby Galaxy Survey (RINGS). We have successfully reduced two tracks of Fabry-P\'erot data for the galaxy NGC 2280 to produce a velocity field of the H-alpha line of excited hydrogen. We have modeled these data with the DiskFit modeling software and found these models to be in excellent agreement both with previous measurements in the literature and with our lower-resolution HI velocity field of the same galaxy. Despite this good agreement, small regions exist where the difference between the H-alpha and HI velocities is larger than would be expected from typical dispersions. We investigate these regions of high velocity difference and offer possible explanations for their existence.