1,406 research outputs found
On the core-halo distribution of dark matter in galaxies
We investigate the distribution of dark matter in galaxies by solving the
equations of equilibrium of a self-gravitating system of massive fermions
(`inos') at selected temperatures and degeneracy parameters within general
relativity. Our most general solutions show, as a function of the radius, a
segregation of three physical regimes: 1) an inner core of almost constant
density governed by degenerate quantum statistics; 2) an intermediate region
with a sharply decreasing density distribution followed by an extended plateau,
implying quantum corrections; 3) an asymptotic, classical
Boltzmann regime fulfilling, as an eigenvalue problem, a fixed value of the
flat rotation curves. This eigenvalue problem determines, for each value of the
central degeneracy parameter, the mass of the ino as well as the radius and
mass of the inner quantum core. Consequences of this alternative approach to
the central and halo regions of galaxies, ranging from dwarf to big spirals,
for SgrA*, as well as for the existing estimates of the ino mass, are outlined.Comment: 8 pages, 5 figures. Accepted for publication by MNRA
Novel constraints on fermionic dark matter from galactic observables I: The Milky Way
We have recently introduced a new model for the distribution of dark matter
(DM) in galaxies based on a self-gravitating system of massive fermions at
finite temperatures, the Ruffini-Arg\"uelles-Rueda (RAR) model. We show that
this model, for fermion masses in the keV range, explains the DM halo of the
Galaxy and predicts the existence of a denser quantum core at the center. We
demonstrate here that the introduction of a cutoff in the fermion phase-space
distribution, necessary to account for the finite Galaxy size, defines a new
solution with a central core which represents an alternative to the black hole
(BH) scenario for SgrA*. For a fermion mass in the range --
~keV, the DM halo distribution is in agreement with the Milky Way rotation
curve data, while harbors a dense quantum core of about
within the S2-star pericenter.Comment: 11 pages, 5 figures. Published in Physics of the Dark Univers
Exploring a Non-Minimal Sterile Neutrino Model Involving Decay at IceCube and Beyond
We study the phenomenology of neutrino decay together with neutrino
oscillations in the context of eV-scale sterile neutrinos. We review the
formalism of visible neutrino decay in which one of the decay products is a
neutrino that potentially can be observed. We apply the formalism developed for
decay to the recent sterile neutrino search performed by IceCube with TeV
neutrinos. We show that for lifetime , the interpretation of the high-energy IceCube analysis can be
significantly changed.Comment: 12 pages, 7 figures. Find code at:
https://github.com/arguelles/nuSQUIDSDeca
The role of self-interacting right-handed neutrinos in galactic structure
It has been shown previously that the DM in galactic halos can be explained
by a self-gravitating system of massive keV fermions (`inos') in thermodynamic
equilibrium, and predicted the existence of a denser quantum core of inos
towards the center of galaxies. In this article we show that the inclusion of
self-interactions among the inos, modeled within a relativistic
mean-field-theory approach, allows the quantum core to become massive and
compact enough to explain the dynamics of the S-cluster stars closest to the
Milky Way's galactic center. The application of this model to other galaxies
such as large elliptical harboring massive central dark objects of is also investigated. We identify these interacting inos with sterile
right-handed neutrinos pertaining to minimal extensions of the Standard Model,
and calculate the corresponding total cross-section within an
electroweak-like formalism to be compared with other observationally inferred
cross-section estimates. The coincidence of an ino mass range of few tens of
keV derived here only from the galactic structure, with the range obtained
independently from other astrophysical and cosmological constraints, points
towards an important role of the right-handed neutrinos in the cosmic
structure.Comment: 33 pages, 9 figures, version to appear in JCA
Field-induced phase transitions of repulsive spin-1 bosons in optical lattices
We study the phase diagram of repulsively interacting spin-1 bosons in
optical lattices at unit filling, showing that an externally induced quadratic
Zeeman effect may lead to a rich physics characterized by various phases and
phase transitions. We find that the main properties of the system may be
described by an effective field model, which provides the precise location of
the phase boundaries for any dimension, being in excellent agreement with our
numerical calculations for one-dimensional systems. Our work provides a
quantitative guide for the experimental analysis of various types of
field-induced quantum phase transitions in spin-1 lattice bosons. These
transitions, which are precluded in spin-1/2 systems, may be realized using an
externally modified quadratic Zeeman coupling, similar to recent experiments
with spinor condensates in the continuum.Comment: 4 pages, 2 figure
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