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We present the HI data for 5 spiral galaxies that, along with their Halpha rotation curves, are used to derive the distribution of dark matter within these objects. A new method for extracting rotation curves from HI data cubes is presented; this takes into account the existence of a warp and minimises projection effects. The rotation curves obtained are tested by taking them as input to construct model data cubes that are compared to the observed ones: the agreement is excellent. On the contrary, the model data cubes built using rotation curves obtained with standard methods, such as the first-moment analysis, fail the test. The HI rotation curves agree well with the Halpha data, where they coexist. Moreover, the combined Halpha + HI rotation curves are smooth, symmetric and extended to large radii. The rotation curves are decomposed into stellar, gaseous and dark matter contributions and the inferred density distribution is compared to various mass distributions: dark haloes with a central density core, $Lambda$ Cold Dark Matter ($Lambda$CDM) haloes (NFW, Moore profiles), HI scaling and MOND. The observations point to haloes with constant density cores of size $r_{core} sim r_{opt}$ and central densities scaling approximately as $rho_0 propto r_{core}^{-2/3}$. $Lambda$CDM models (which predict a central cusp in the density profile) are in clear conflict with the data. HI scaling and MOND cannot account for the observed kinematics: we find some counter-examples.
We present a model for the dark matter in spiral galaxies, which is a result of a static and axial symmetric exact solution of the Einstein-Dilaton theory. We suposse that dark matter is a scalar field endowed with a scalar potential. We obtain that
In the absence of the physical understanding of the phenomenon, different empirical laws have been used as approximation for distribution of dark matter in galaxies and clusters of galaxies. We suggest a new profile which is not empirical in nature,
`Conspiracy between the dark and the baryonic mater prohibits an unambiguous decomposition of disc galaxy rotation curves into the corresponding components. Several methods have been proposed to counter this difficulty, but their results are widely d
We construct mass models of 28 S0-Sb galaxies. The models have an axisymmetric stellar component and a NFW dark halo and are constrained by observed Ks-band photometry and stellar kinematics. The median dark halo virial mass is 10^12.8 Msun, and the
We analyse a high-resolution, fully cosmological, hydrodynamical disc galaxy simulation, to study the source of the double-exponential light profiles seen in many stellar discs, and the effects of stellar radial migration upon the spatio-temporal evo