The CUSP/CORE problem from a 2D view
Juan C. B. Pineda, C. Mendes de Oliveira, C. E. Barbosa, P. Amram, Valentin Perret · 2013
It has been claimed for a long time that the shapes of galactic dark matter haloes in numerical simulations are not consistent with those of real galaxies, as inferred from observations.While the former may have a steep density profiles in the center, the latter may reveal nearly flat central dark matter distributions, and that is why this controversy is known as the "cusp/core problem".Nevertheless, it is important to highlight that most of the comparisons have been made using results from dark-matter-only simulations, e.g, ignoring the real effects of baryonic feedback at galactic scales.On the other hand, many observational works rely on the assumption that galactic disks are highly symmetric rotating structures, which is rarely the case either for light distributions or for velocity fields.In this work we use high-resolution Hα velocity fields to make a comparison between the results obtained when perfectly rotating disks are assumed, against the results obtained using a harmonic decomposition to effectively separate non-circular motions from the pure circular component, which may be a better tracer of the underlying potential.We have selected a sample of galaxies analyzed and published by different authors.These have been considered good candidates for mass modeling, and have, therefore, played a role into the cusp/core controversy.Following a classical approach to create mass models of rotating galaxies we show that conclusions about the cuspiness of the DM halo could be affected by the way the data are treated, and that there is a general trend towards higher mass-to-light ratios of baryonic components when the "pure rotation" assumption is considered.