Dark matter axions revisited (original) (raw)
Related papers
Axion cold dark matter revisited
Journal of Physics: Conference Series, 2010
We study for what specific values of the theoretical parameters the axion can form the totality of cold dark matter. We examine the allowed axion parameter region in the light of recent data collected by the WMAP5 mission plus baryon acoustic oscillations and supernovae [1], and assume an inflationary scenario and standard cosmology. We also upgrade the treatment of anharmonicities in the axion potential, which we find important in certain cases. If the Peccei-Quinn symmetry is restored after inflation, we recover the usual relation between axion mass and density, so that an axion mass ma = (85 ± 3) µeV makes the axion 100% of the cold dark matter. If the Peccei-Quinn symmetry is broken during inflation, the axion can instead be 100% of the cold dark matter for ma < 15 meV provided a specific value of the initial misalignment angle θi is chosen in correspondence to a given value of its mass ma. Large values of the Peccei-Quinn symmetry breaking scale correspond to small, perhaps uncomfortably small, values of the initial misalignment angle θi.
Axion cold dark matter in view of BICEP2 results
Phys. Rev. Lett. 113, 011802 (2014)
The properties of axions that constitute 100% of cold dark matter (CDM) depend on the tensor- to-scalar ratio r at the end of inflation. If r = 0.20+0.07 as reported by the BICEP2 collaboration, −0.05 then “half” of the CDM axion parameter space is ruled out. Namely, the Peccei-Quinn symmetry must be broken after the end of inflation, and axions do not generate non-adiabatic primordial fluctuations. The cosmic axion density is then independent of the tensor-to-scalar ratio r, and the axion mass is expected to be in a narrow range that however depends on the cosmological model before primordial nucleosynthesis. In the standard ΛCDM cosmology, the CDM axion mass range is ma = (71 ± 2) μeV (αdec + 1)6/7 , where αdec is the fractional contribution to the cosmic axion density from decays of axionic strings and walls.
Axion dark matter in the post-inflationary Peccei-Quinn symmetry breaking scenario
Physical review, 2016
We consider extensions of the Standard Model in which a spontaneously broken global chiral Peccei-Quinn (PQ) symmetry arises as an accidental symmetry of an exact ZN symmetry. For N = 9 or 10, this symmetry can protect the accion-the Nambu-Goldstone boson arising from the spontaneous breaking of the accidental PQ symmetry-against semi-classical gravity effects, thus suppressing gravitational corrections to the effective potential, while it can at the same time provide for the small explicit symmetry breaking term needed to make models with domain wall number NDW > 1, such as the popular Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) model (NDW = 6), cosmologically viable even in the case where spontaneous PQ symmetry breaking occurred after inflation. We find that N = 10 DFSZ accions with mass mA ≈ 3.5-4.2 meV can account for cold dark matter and simultaneously explain the hints for anomalous cooling of white dwarfs. The proposed helioscope International Axion Observatory-being sensitive to solar DFSZ accions with mass above a few meV-will decisively test this scenario.
Cold Dark Matter Axion - A New Mass Window from Cosmological Bounds
ArXiv, 2024
Based upon a previous axion mass proposal and detection scheme, as well as considering the axion mass ranges suggested by cogent simulations in recent years, we present a revised axion/ALP search strategy and our calculations, concentrating on a narrow axion mass (and corresponding Compton frequency) window in this report. The window comprises the spectral region of 18.99 to 19.01GHz (that falls within the Ku microwave band), with a center frequency of 19.00GHz (+0.1GHz), with equivalence to am axion mass range of 78.6 to 79.6 eV, with the center mass at the value of 78.582 (+5.0) eV, our suggested most likely value for an axionic/ALP field mass, if these fields exist. Our search strategy, as summarized herewith, is based upon the assumption that the dark matter that exists in the current epoch of our physical universe is dominated by axions and thus the local observable axion density is the density of the light cold dark matter, permeating our local neighborhood (mainly in the Milky Way galactic halo). Some ideas and the design of an experiment, built around a Josephson Parametric Amplifier and Resonant Tunneling Diode combo installed in a resonant RF cavity, are also introduced in this report.
Axion cold dark matter: Status after Planck and BICEP2
Physical Review D, 2014
We investigate the axion dark matter scenario (ADM), in which axions account for all of the dark matter in the Universe, in light of the most recent cosmological data. In particular, we use the Planck temperature data, complemented by WMAP E-polarization measurements, as well as the recent BICEP2 observations of B-modes. Baryon Acoustic Oscillation data, including those from the Baryon Oscillation Spectroscopic Survey, are also considered in the numerical analyses.
Physical Review D
We study the future prospects of the 21 cm forest observations on the axionlike dark matter when the spontaneous breaking of global Peccei-Quinn (PQ) symmetry occurs after the inflation. The large isocurvature perturbations of order unity sourced from axionlike particles can result in the enhancement of minihalo formation, and the subsequent hierarchical structure formation can affect the minihalo abundance whose masses can exceed Oð10 4 Þ M ⊙ relevant for the 21 cm forest observations. We show that the 21 cm forest observations are capable of probing the axionlike particle mass in the range 10 −18 ≲ m a ≲ 10 −12 eV for the temperature independent axion mass. For the temperature dependent axion mass, the zero temperature axion mass scale for which the 21 cm forest measurements can be affected is extended further to as big as of order 10 −6 eV.
Light axion-like dark matter must be present during inflation
Physical Review D, 2017
Axion-like particles (ALPs) might constitute the totality of the cold dark matter (CDM) observed. The parameter space of ALPs depends on the mass of the particle m and on the energy scale of inflation H I , the latter being bound by the non-detection of primordial gravitational waves. We show that the bound on H I implies the existence of a mass scale ¯ m = 10 neV ÷ 0.5 peV, depending on the ALP susceptibility , such that the energy density of ALPs of mass smaller than ¯ m is too low to explain the present CDM budget, if the ALP field has originated after the end of inflation. This bound a↵ects Ultra-Light Axions (ULAs), which have recently regained popularity as CDM candidates. Light (m < m) ALPs can then be CDM candidates only if the ALP field has already originated during the inflationary period, in which case the parameter space is constrained by the non-detection of axion isocurvature fluctuations. We comment on the e↵ects on these bounds from additional physics beyond the Standard Model, besides ALPs.
Axion cold dark matter in nonstandard cosmologies
Physical Review D, 2010
We study the parameter space of cold dark matter axions in two cosmological scenarios with non-standard thermal histories before Big Bang nucleosynthesis: the Low Temperature Reheating (LTR) cosmology and the kination cosmology. If the Peccei-Quinn symmetry breaks during inflation, we find more allowed parameter space in the LTR cosmology than in the standard cosmology and less in the kination cosmology. On the contrary, if the Peccei-Quinn symmetry breaks after inflation, the Peccei-Quinn scale is orders of magnitude higher than standard in the LTR cosmology and lower in the kination cosmology. We show that the axion velocity dispersion may be used to distinguish some of these non-standard cosmologies. Thus, axion cold dark matter may be a good probe of the history of the Universe before Big Bang nucleosynthesis. PACS numbers: 14.80.Va, 95.35.+d, 98.80.Cq The standard cosmological model has been tested up to a temperature T ∼ 1 MeV, or down to times as short as ∼ 1 s, when Big Bang nucleosynthesis (BBN) occurred. The success of the BBN theory is due to its great precision in predicting the primordial abundance of light elements D, 4 He and 7 Li. For the success of BBN, the Universe must be radiationdominated at temperatures T > ∼ 4 MeV [1]. However, due to lack of data prior to BBN, the history of the Universe in the pre-BBN epoch T > ∼ 4 MeV is only indirectly inferred.
Axions as a model of Dark Matter
Journal of Student Research
The true nature of dark matter is an extremely important and fundamental problem in the study of astrophysics, particle physics, cosmology and many other areas within the study of physics. This paper presents experimental evidence for the existence of dark matter through discussing the experimental results of mass profiling a galaxy and gravitational lensing. The fundamental properties of dark matter are then discussed, and evidence for these properties is presented. This allows further discussion of one of the most promising models of dark matter - the axion. The purpose of this paper is to present the evidence for the axion model, describe the nature of the theoretical axion particle, and to highlight the effects this model would have on other theories in physics such as solving the Strong CP Problem in the theory of quantum chromodynamics.