GHASP: an Hα kinematic survey of spiral and irregular galaxies – VI. New Hα data cubes for 108 galaxies

Abstract

We present the Fabry–Perot observations obtained for a new set of 108 galaxies in the frame of the Gassendi Hα survey of SPirals (GHASP). The GHASP survey consists of 3D Hα data cubes for 203 spiral and irregular galaxies, covering a large range in morphological types and absolute magnitudes, for kinematics analysis. The new set of data presented here completes the survey. The GHASP sample is by now the largest sample of Fabry–Perot data ever published. The analysis of the whole GHASP sample will be done in forthcoming papers. Using adaptive binning techniques based on Voronoi tessellations, we have derived Hα data cubes from which are computed Hα 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 field rather 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. The 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 disc. The consistency of the velocity amplitude of our rotation curves has 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.

Astrophysical tests of modified gravity: the morphology and kinematics of dwarf galaxies

“…We quantify the asymmetry in rotation curves for each galaxy using the abolute value of the weighted average of difference between approaching and receding sides of the rotation curves (|∆v|) about the stellar centroids (Epinat et al 2008). This asymmetry is better seen near the center of the galaxy and therefore we focus on the inner part of the rotation curves.…”

“…We use Hα rotation curves for nearly 200 disk galaxies from the Gassendi Hα survey of spirals (GHASP) archive (see Epinat et al 2008, and references therein) to search for asymmetry in rotation curves. GHASP is an Hα kinematic survey of spiral and irregular galaxies.…”

Star formation in the intragroup medium and other diagnostics of the evolutionary stages of compact groups of galaxies

“…UGC 12754, UGC 11407 andUGC 1256). Given that the kinematic PA is so perturbed by the bar, it is better to use the morphological PA to draw the RC (see Epinat et al 2008a). The monochromatic map shows several HII regions.…”

“…In most cases there was clearly a decoupling between the morphological and kinematic centers (see Amram et al 2007). Kinematic position angles, inclinations, systemic velocities (see Table 1) and rotation curves were derived from the velocity fields using the procedure developed by Epinat et al (2008a). The position of the morphological center for each galaxy is marked with a plus sign in the velocity fields of Figs.…”

“…No flux calibration was attempted. Data reduction was performed using software developed by Daigle et al (2006; see also Epinat et al 2008a). The data for HCG 100 was taken from Plana et al (2003).…”