Dynamics of blue compact galaxies, as revealed by their H-alpha velocity fields I. The data, velocity fields and rotation curves

TL;DR

This study presents detailed H-alpha velocity fields and rotation curves for six blue compact galaxies and their companions, revealing complex kinematics in BCGs and providing estimates of their dynamical and gas masses.

Contribution

First extensive analysis of optical velocity fields in BCGs using Fabry-Perot interferometry, highlighting complex dynamics and mass estimates.

Findings

BCGs exhibit perturbed and complex velocity fields.

Companion galaxies show regular velocity fields.

Rotation is present in all studied galaxies.

Abstract

Observations of six luminous blue compact galaxies (BCGs) and two star forming companion galaxies were carried out with the CIGALE scanning Fabry-Perot interferometer attached to the ESO 3.6m telescope on La Silla. The observations were made in the H-alpha emission line which is prominent in BCGs. A velocity sampling of 5 km/s and a pixel size of 0.9 arcseconds were used. In this paper we present the observations and the data together with the velocity fields and the derived rotation curves. In addition we provide rough estimates of the total dynamical mass and of the ionised gas mass for each galaxy. All galaxies display rotation, but while the companion galaxies have regular velocity fields, those of the BCGs are complex and appear perturbed. This is the most extensive study to date of the optical velocity fields of BCGs. The interpretation of these results will be presented in a forthcoming paper (Paper II).