Detection of non-ordered central gas motions in a sample of four low surface brightness galaxies

Abstract

We present integral-field spectroscopy of the ionized gas in the central regions of four galaxies with a low surface brightness disk taken with the Visible Multi Object Spectrograph at the Very Large Telescope and aimed at testing the accuracy in the determination of the central logarithmic slope $\alpha$ of the mass density radial profile $\rho (r)\propto r^{\alpha }$ in this class of objects. For all the sample galaxies we subtracted from the observed velocity field the best-fit model of gas in circular motions and derived the residuals. Only ESO-LV 5340200 is characterized by a regular velocity field. We extracted the velocity curves of this galaxy along several position angles, in order to estimate the uncertainty in deriving the central gradient of the total mass density from long-slit spectroscopy. We report the detection of strong non-ordered motions of the ionized gas in three out of four sample galaxies. The deviations have velocity amplitudes and spatial scales that make not possible to disentangle between cuspy and core density radial profiles.

arXiv comment7 pages, 4 figures, accepted for publication in A&A

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• Origin and Dynamical Support of Ionized Gas in Galaxy Bulges
• VIMOS-VLT Integral Field Kinematics of the Giant Low Surface Brightness Galaxy ESO 323-G064
• Low surface brightness galaxies mass profiles as a consequence of galactic evolution