30 research outputs found
An ecological approach to problems of Dark Energy, Dark Matter, MOND and Neutrinos
Modern astronomical data on galaxy and cosmological scales have revealed
powerfully the existence of certain dark sectors of fundamental physics, i.e.,
existence of particles and fields outside the standard models and inaccessible
by current experiments. Various approaches are taken to modify/extend the
standard models. Generic theories introduce multiple de-coupled fields A, B, C,
each responsible for the effects of DM (cold supersymmetric particles), DE
(Dark Energy) effect, and MG (Modified Gravity) effect respectively. Some
theories use adopt vanilla combinations like AB, BC, or CA, and assume A, B, C
belong to decoupled sectors of physics. MOND-like MG and Cold DM are often
taken as opposite frameworks, e.g. in the debate around the Bullet Cluster.
Here we argue that these ad hoc divisions of sectors miss important clues from
the data. The data actually suggest that the physics of all dark sectors is
likely linked together by a self-interacting oscillating field, which governs a
chameleon-like dark fluid, appearing as DM, DE and MG in different settings. It
is timely to consider an interdisciplinary approach across all semantic
boundaries of dark sectors, treating the dark stress as one identity, hence
accounts for several "coincidences" naturally.Comment: 12p, Proceedings to the 6-th Int. Conf. of Gravitation and Cosmology.
Neutrino section expande
The Cosmic Microwave Background and Particle Physics
In forthcoming years, connections between cosmology and particle physics will
be made increasingly important with the advent of a new generation of cosmic
microwave background (CMB) experiments. Here, we review a number of these
links. Our primary focus is on new CMB tests of inflation. We explain how the
inflationary predictions for the geometry of the Universe and primordial
density perturbations will be tested by CMB temperature fluctuations, and how
the gravitational waves predicted by inflation can be pursued with the CMB
polarization. The CMB signatures of topological defects and primordial magnetic
fields from cosmological phase transitions are also discussed. Furthermore, we
review current and future CMB constraints on various types of dark matter (e.g.
massive neutrinos, weakly interacting massive particles, axions, vacuum
energy), decaying particles, the baryon asymmetry of the Universe,
ultra-high-energy cosmic rays, exotic cosmological topologies, and other new
physics.Comment: 43 pages. To appear in Annual Reviews of Nuclear and Particle Scienc
Ruling Out Bosonic Repulsive Dark Matter in Thermal Equilibrium
Self-interacting dark matter (SIDM), especially bosonic, has been considered
a promising candidate to replace cold dark matter (CDM) as it resolves some of
the problems associated with CDM. Here, we rule out the possibility that dark
matter is a repulsive boson in thermal equilibrium. We develop the model first
proposed by Goodman (2000) and derive the equation of state at finite
temperature. Isothermal spherical halo models indicate a Bose-Einstein
condensed core surrounded by a non-degenerate envelope, with an abrupt density
drop marking the boundary between the two phases. Comparing this feature with
observed rotation curves constrains the interaction strength of our model's DM
particle, and Bullet Cluster measurements constrain the scattering cross
section. Both ultimately can be cast as constraints on the particle's mass. We
find these two constraints cannot be satisfied simultaneously in any realistic
halo model---and hence dark matter cannot be a repulsive boson in thermal
equilibrium. It is still left open that DM may be a repulsive boson provided it
is not in thermal equilibrium; this requires that the mass of the particle be
significantly less than a millivolt.Comment: 13 pages, 3 figures, 1 table, accepted MNRAS August 9 201
Dark Energy vs. Modified Gravity
Understanding the reason for the observed accelerated expansion of the
Universe represents one of the fundamental open questions in physics. In
cosmology, a classification has emerged among physical models for the
acceleration, distinguishing between Dark Energy and Modified Gravity. In this
review, we give a brief overview of models in both categories as well as their
phenomenology and characteristic observable signatures in cosmology. We also
introduce a rigorous distinction between Dark Energy and Modified Gravity based
on the strong and weak equivalence principles.Comment: 29 pages, 4 figures; invited review submitted to Annual Reviews of
Nuclear and Particle Science; v2: some pertinent references added; v3: table
with constraints added, reflects published version; v4 [trivial]: fixed
missing references in arxiv versio
Gravity, Curvature and Energy: Gravitational Field Intentionality to the Cohesion and Union of the Universe
We use the quantum operators
O
c
G
,
which are diffeomorphisms of gravity creating the intentionality under the action integrals to prove and determine the gluing intention for adherence of the matter-energy (taking the corresponding mass-energy tensor T ab
) to create complex bodies in the scale of conforming the fragmented Universe such as we know. The reverse is the planting of the energy model of gravity in accordance with the implications in space-time due to the diffeomorphisms of gravity, which were designed to explain the existence of the intention as kernel of the integral operators of the actions with this intention as direction of the energy-matter. The time, in particular, can be shown through instantons of a gauge field (this as electromagnetic field, and in this case appears the torsion) of gravity, which appears in natural way as the same integral operators obtained. Finally, using the complex Riemannian structure of our model of the space-time, and the K-invariant G-structure of the orbits used to obtain curvature, are obtained as consequences of the diffeomorphisms, the field equations to the energy-matter tensor density in each case of the gravitational field