Cosmological tension of ultralight axion dark matter and its solutions

We investigate the production of photons from coherently oscillating, spatially localized clumps of axionic fields (oscillons and axion stars) in the presence of external electromagnetic fields. We delineate different qualitative behaviour of the photon luminosity in terms of an effective dimensionless coupling parameter constructed out of the axion-photon coupling, and field amplitude, oscillation frequency and radius of the axion star. For small values of this dimensionless coupling, we provide a general analytic formula for the dipole radiation field and the photon luminosity per solid angle, including a strong dependence on the radius of the configuration. For moderate to large coupling, we report on a non-monotonic behavior of the luminosity with the coupling strength in the presence of external magnetic fields. After an initial rise in luminosity with the coupling strength, we see a suppression (by an order of magnitude or more compared to the dipole radiation approximation) at moderately large coupling. At sufficiently large coupling, we find a transition to a regime of exponential growth of the luminosity due to parametric resonance. We carry out 3+1 dimensional lattice simulations of axion electrodynamics, at small and large coupling, including non-perturbative effects of parametric resonance as well as backreaction effects when necessary. We also discuss medium (plasma) effects that lead to resonant axion to photon conversion, relevance of the coherence of the soliton, and implications of our results in astrophysical and cosmological settings.

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“…c sub 1. For some theoretical work on models with a large axion-photon coupling, see [115][116][117][118][119][120][121].…”

Section: Jhep06(2021)182mentioning

confidence: 99%

Dipole radiation and beyond from axion stars in electromagnetic fields

Amin

Long

Mou

et al. 2021

J. High Energ. Phys.

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“…It has been noted in [79] that for ultralight axions, cosmological considerations requiring axions to have a matter-power spectrum that matches that of cold dark matter constrains the magnitude of the axion couplings to the visible sector. As a result, at least part of the parameter space the cosmic distance measurements could probe is associated with non-trivial axion models, in which axions have an abnormally large coupling to photons, as constructed in [79][80][81][82].…”

Section: Jhep02(2022)103mentioning

confidence: 99%

Constraints on axions from cosmic distance measurements

Buen-Abad

Fan

Sun

2022

J. High Energ. Phys.

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Axion couplings to photons could induce photon-axion conversion in the presence of magnetic fields in the Universe. This conversion could impact various cosmic distance measurements, such as luminosity distances to type Ia supernovae and angular distances to galaxy clusters, in different ways. In this paper we consider different combinations of the most up-to-date distance measurements to constrain the axion-photon coupling. Employing the conservative cell magnetic field model for the magnetic fields in the intergalactic medium (IGM) and ignoring the conversion in the intracluster medium (ICM), we find the upper bounds on axion-photon couplings to be around 5×10−12 (nG/B) $$ \sqrt{\mathrm{Mpc}/s} $$ Mpc / s GeV–1 for axion masses ma below 10−13 eV, where B is the strength of the IGM magnetic field, and s is the comoving size of the magnetic domains. When including the conversion in the ICM, the upper bound is lowered and could reach 5 × 10−13 GeV−1 for ma< 5 × 10−12 eV. While this stronger bound depends on the ICM modeling, it is independent of the strength of the IGM magnetic field, for which there is no direct evidence yet. These constraints could be placed on firmer footing with an enhanced understanding and control of the astrophysical uncertainties associated with the IGM and ICM. All the bounds are determined by the shape of the Hubble rate as a function of redshift reconstructable from various distance measurements, and insensitive to today’s Hubble rate, of which there is a tension between early and late cosmological measurements. As an appendix, we discuss the model building challenges of the use of photon-axion conversion to make type Ia supernovae brighter to alleviate the Hubble problem/crisis.

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“…For ALP DM, ρ a = ρ DM and in = 1 are also assumed. Another interesting possibility is that one of g aX (X = γ , N, e) is much stronger than the others, e.g., (a) the photophilic limit with c B, W â c G, q (37,38,(119)(120)(121), (b) the nucleophilic limit with c q â c G, W, B (120)(121)(122), and (c) the leptophilic limit with c e â c G, q (121,123). Since most axion search experiments are designed to be sensitive to one specific coupling, these limits may also be more easily probed by ongoing or planned experiments.…”

Section: Coupling Hierarchies For Laboratory Searches For Axionsmentioning

confidence: 99%

Recent Progress in the Physics of Axions and Axion-Like Particles

Choi

Shin

2021

Annu. Rev. Nucl. Part. Sci.

125

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The axion is a light pseudoscalar particle postulated to solve issues with the Standard Model, including the strong CP problem and the origin of dark matter. In recent years, there has been remarkable progress in the physics of axions in several directions. An unusual type of axion-like particle termed the relaxion was proposed as a new solution to the weak scale hierarchy problem. There are also new ideas for laboratory, astrophysical, or cosmological searches for axions; such searches can probe a wide range of model parameters that were previously inaccessible. On the formal theory side, the weak gravity conjecture indicates a tension between quantum gravity and a trans-Planckian axion field excursion. Many of these developments involve axions with hierarchical couplings. In this article, we review recent progress in axion physics, with particular attention paid to hierarchies between axion couplings. We emphasize that the parameter regions of hierarchical axion couplings are the most accessible experimentally. Moreover, such regions are often where important theoretical questions in the field are addressed, and they can result from simple model-building mechanisms. Expected final online publication date for the Annual Review of Nutrition, Volume 41 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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Cosmological tension of ultralight axion dark matter and its solutions

Cited by 25 publications

References 84 publications

Dipole radiation and beyond from axion stars in electromagnetic fields

Dipole radiation and beyond from axion stars in electromagnetic fields

Constraints on axions from cosmic distance measurements

Recent Progress in the Physics of Axions and Axion-Like Particles

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