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This paper has been withdrawn owing a re-arrangement of two previously submitted papers. The new version of the theoretical work on the triaxial shape of dark matter haloes can be found at the ArXiv astro-ph list (CO) as article 1104.2905, Comment: This paper has been withdrawn owing a re-arrangement of two previously submitted papers. The new version of the theoretical work on the triaxial shape of dark matter haloes can be found at the ArXiv astro-ph list (CO) as article 1104.2905

In a recent paper, Salvador-Sol\'e et al. (2012) have derived the typical inner structure of dark matter haloes from that of peaks in the initial random Gaussian density field, determined by the power-spectrum of density perturbations characterising the hierarchical cosmology under consideration. In the present paper, we extend this formalism to the typical kinematics and triaxial shape of haloes. Specifically, we establish the link between such halo properties and the power-spectrum of density perturbations through the typical shape of peaks. The trends of the predicted typical halo shape, pseudo phase-space density and anisotropy profiles are in good agreement with the results of numerical simulations. Our model sheds light on the origin of the power-law-like pseudo phase-space density profile for virialised haloes., Comment: 18 pages, 6 figures. Published in MNRAS

In two previous papers (Salvador-Sol\'e 2012a,b), it was shown that: i) the typical structural and kinematic properties of haloes in (bottom-up) hierarchical cosmologies endowed with random Gaussian density perturbations of dissipationless collisionless dark matter emerge naturally from the typical properties of peaks in the primordial density field and ii) halo statistics are well described by the peak formalism. In the present paper, we use these results to model halo substructure. Specifically, making use of the peak formalism and the fact that accreting haloes evolve from the inside-out, we derive the subhalo mass abundance and number density profile per infinitesimal mass for subhaloes of different masses, as a function of the subhalo maximum circular velocity or mass, before and after the tidal truncation of subhaloes by the host potential well. The subhalo properties obtained by assuming that subhaloes are mainly made of diffuse particles are in very good agreement with those found in current high-resolution N-body simulations. We also predict the subhalo properties in the opposite extreme case, likely better suited for the real universe in CDM cosmologies, that haloes are made of subhaloes within subhaloes at all scales., Comment: 15 pages, 7 figures. Submitted to MNRAS

We derive the density profile for collisionless dissipationless dark matter haloes in hierarchical cosmologies making use of the Secondary Infall (SI) model. The novelties are: i) we deal with triaxial virialised objects; ii) their seeds in the linear regime are peaks endowed with {\it unconvolved} spherically averaged density profiles according to the peak formalism; iii) the initial peculiar velocities are taken into account; and iv) accreting haloes are assumed to develop from the inside out, keeping the instantaneous inner system unaltered. The validity of this latter assumption is accurately checked by comparing analytical predictions on such a growth with the results of numerical simulation. We show that the spherically averaged density profile of virialised objects can be inferred with no need to specify their shape. The {\it typical} spherically averaged halo density profile is inferred, down to arbitrarily small radii, from the power-spectrum of density perturbations. The predicted profile in the $\Lambda$CDM cosmology is approximately described by an Einasto profile, meaning that it does not have a cusp but rather a core, where the inner slope slowly converges to zero. Down to one hundredth the total radius, the profile has the right NFW and Einasto forms, being close to the latter down to a radius of about four orders of magnitude less. The inner consistency of the model implies that the density profiles of haloes harbour no information on their past aggregation history. This would explain why major mergers do not alter the typical density profile of virialised objects formed by SI and do not invalidate the peak formalism based on such a formation., Comment: 14 pages, 7 figures. Published in MNRAS

In a series of recent papers, a new formalism has been developed that explains the inner structure of dark matter halos as collisionless, dissipationless systems assembled through mergers and accretion at the typical cosmological rate. Nearby ellipticals are also collisionless, dissipationless systems assembling their mass through mergers, but contrarily to the former structures they do not continuously accrete external matter because they are shielded by their host halos. Here we explore the idea that the infall of their own matter ejected within the halo on the occasion of a violent merger can play a role similar to external accretion in halos. The predicted stellar mass density profile fits the observed one, and the empirical total mass density profile is also recovered., Comment: 4 pages, 2 figures