Density profiles of dark matter haloes on galactic and cluster scales

¹ Dipartimento di Fisica e Astronomia, Universitá di Catania, Viale Andrea Doria 6, 95125 Catania, Italy e-mail: antonino.delpopolo@oact.inaf.it
² Argelander-Institut für Astronomie, Auf dem Hügel 71, 53121 Bonn, Germany
³ Istanbul Technical University, Ayazaga Campus, Faculty of Science and Letters, 34469 Maslak/ISTANBUL, Turkey

Received: 24 November 2008
Accepted: 7 May 2009

Abstract

Aims. In the present paper, we improve the “extended secondary infall model” (ESIM) of Williams and collaborators to obtain further insights into the cusp/core problem.

Methods. A secondary infall model close to the collapse reality is obtained by simultaneously taking into account effects that till now have been studied separately, namely ordered and random angular momentum, dynamical friction, and baryon adiabatic contraction. The model is applied to structures on galactic scales (normal and dwarf spiral galaxies) and on galaxy cluster scales.

Results. Our results imply that angular momentum and dynamical friction are able, on galactic scales, of overcoming the competing effect of adiabatic contraction and eliminating the Cusp. The NFW profile is not the standard outcome of the model, and it can be recovered in our model only if the system consists entirely of dark matter and the magnitude of angular momentum and dynamical friction are lower than the values predicted by the model itself. Comparison of the rotation curves of LSB galaxies with the results of our model are in good agreement. On scales smaller than 10¹¹ h^-1 , the slope is , and on cluster scales we observe a similar evolution in the dark matter density profile but in this case the density profile slope flattens to for a cluster of 10¹⁴ h^-1 . The total mass profile differs from that of dark matter showing a central cusp that is reproduced by a NFW model.