Universal relations with fermionic dark matter

¹ Dip. di Fisica, Sapienza Università di Roma, Piazzale Aldo Moro 5, I-00185 Rome, Italy
² University of Nice-Sophia Antipolis, 28 Av. de Valrose, 06103 Nice Cedex 2, France
³ ICRANet, Piazza della Repubblica 10, I-65122 Pescara, Italy
⁴ ICRANet-Rio, Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, 22290–180 Rio de Janeiro, Brazil
⁵ Grupo de Astrofísica, Relatividad y Cosmología, Facultad de Ciencias Astronómicas y Geofísicas, UNLP and CONICET Paseo del Bosque S/N 1900, La Plata, Buenos Aires, Argentina

^* e-mail: andreas.krut@icranet.org (ICRANet)

Published online: 9 January 2018

Abstract

We have recently introduced a new model for the distribution of dark matter (DM) in galaxies, the Ruffini-Argüelles-Rueda (RAR) model, based on a self-gravitating system of massive fermions at finite temperatures. The RAR model, for fermion masses above keV, successfully describes the DM halos in galaxies, and predicts the existence of a denser quantum core towards the center of each configuration. We demonstrate here, for the first time, that the introduction of a cutoff in the fermion phase-space distribution, necessary to account for galaxies finite size and mass, defines a new solution with a compact quantum core which represents an alternative to the central black hole (BH) scenario for SgrA*. For a fermion mass in the range 48keV ≤ mc² ≤ 345keV, the DM halo distribution fulfills the most recent data of the Milky Way rotation curves while harbors a dense quantum core of 4×10⁶M_⊙ within the S2 star pericenter. In particular, for a fermion mass of mc² ∼ 50keV the model is able to explain the DM halos from typical dwarf spheroidal to normal elliptical galaxies, while harboring dark and massive compact objects from ∼ 10³M_⊙ tp to 10⁸M_⊙ at their respective centers. The model is shown to be in good agreement with different observationally inferred universal relations, such as the ones connecting DM halos with supermassive dark central objects. Finally, the model provides a natural mechanism for the formation of supermassive BHs as heavy as few ∼ 10⁸M_⊙. We argue that larger BH masses (few ∼ 10⁹−¹⁰M_⊙) may be achieved by assuming subsequent accretion processes onto the above heavy seeds, depending on accretion efficiency and environment.