Talk detail

Participant	Argüelles, Carlos
Institution	ICRANet - Piazza della Repubblica, 10 - Pescara - Abruzzo - Italy

Session	DM4	Accepted	Yes	Order	3	Time	14:55	15'
Talk	Oral abstract	Title	Dark Matter phase-transition
Coauthors	Ruffini, Remo; Argüelles, Carlos R.; Rueda, Jorge A.
Abstract	Attempts of studying galactic structures in terms of fundamental physical principles such as thermodynamics and statistical physics has long been considered, since galaxies present many quasi-universal self-organized properties such as the constant mean surface density at halo-scale lengths, or the fact that dark matter halos are well fitted by different phenomenological profiles which resemble isothermal spheres. Within this context, the more subtle problem of understanding the relaxation processes which take place before a galactic halo enters in the steady state we observe, is briefly reviewed, with special attention to collisionless relaxation processes leading to quasi-stationary-states (QSS) described by Fermi-Dirac-like distribution functions. In particular, in the case of well mixed fermionic dark matter composite QSS, I present the equilibrium configurations which reproduce galactic data, and analyze the physical conditions under which the system undergoes a gravitational phase transition depending on a critical temperature, and its possible relation with non-linear structure formation.
Pdf file

Session	DM1	Accepted	Yes	Order	5	Time	16:50	15'
Talk	Oral abstract	Title	A novel scenario for self-interacting dark matter
Coauthors	Argüelles, C. R., Mavromatos N. E., Rueda J. A., Ruffini R.
Abstract	A possible self-interacting nature for the dark matter particles on cluster and galaxy scales started to be seriously considered after the discovery of the 'bullet-cluster' as well as upon realizing that an hypothesis of this kind could lead to shallower inner dark matter profiles with respect to numerically inferred ones within the CDM paradigm. If true, this appealing idea should be able to answer the following key questions: are self-interactions among the DM particles really necessary to deal with the overall distribution of DM in galaxies?, if so, which are the effects of the new interactions in the shape of the DM density profiles, and finally, what information can be gained regarding an underlying field microscopic model of the particles? On the basis of a fermionic dark matter model on galaxy scales, I describe a novel astrophysical scenario where the self-interacting behaviour of the particles arise analogously as in ultra-cold atomic collisions in (effective) Fermi gases studied in laboratory, and study its effects on the distribution of dark matter through the center of the Galaxy.
Pdf file