GHASP : An Halpha kinematic survey of spiral and irregular galaxies - VI. New Halpha data cubes for 108 galaxies

TL;DR

This paper presents new Halpha data cubes for 108 galaxies, completing the GHASP survey, and introduces improved methods for deriving galaxy kinematics, resulting in more accurate rotation curves and kinematic parameters.

Contribution

It provides the largest Fabry-Perot Halpha survey dataset with novel analysis techniques based on the entire 2D velocity field and residuals.

Findings

Kinematic and morphological position angles differ, especially in low-inclination galaxies.

High-inclination galaxies show good agreement between kinematic and morphological inclinations.

Rotation curves are consistent with the Tully-Fisher relation, with some deviations for low-inclination and fast-rotating galaxies.

Abstract

We present the Fabry-Perot observations obtained for a new set of 108 galaxies that completes the GHASP survey (Gassendi HAlpha survey of SPirals). The GHASP survey consists of 3D Ha data cubes for 203 spiral and irregular galaxies, covering a large range in morphological types and absolute magnitudes, for kinematics analysis. The GHASP sample is by now the largest sample of Fabry-Perot data ever published. We have derived Ha data cubes from which are computed Ha maps, radial velocity fields as well as residual velocity fields, position-velocity diagrams, rotation curves and the kinematical parameters for almost all galaxies. Original improvements in the determination of the kinematical parameters, rotation curves and their uncertainties have been implemented in the reduction procedure. This new method is based on the whole 2D velocity field and on the power spectrum of the residual velocity fieldrather than the classical method using successive crowns in the velocity field. Among the results, we point out that morphological position angles have systematically higher uncertainties than kinematical ones, especially for galaxies with low inclination. Morphological inclination of galaxies having no robust determination of their morphological position angle cannot be constrained correctly. Galaxies with high inclination show a better agreement between their kinematical inclination and their morphological inclination computed assuming a thin disk. The consistency of the velocity amplitude of our rotation curves have been checked using the Tully-Fisher relationship. Our data are in good agreement with previous determinations found in the literature. Nevertheless, galaxies with low inclination have statistically higher velocities than expected and fast rotators are less luminous than expected.