Detecting axion dark matter with radio lines from neutron star populations

Safdi, Benjamin R.; Zhan, Sun; Chen, Alexander Y.

doi:10.1103/physrevd.99.123021

Cited by 125 publications

(139 citation statements)

References 111 publications

(228 reference statements)

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“…Second we estimated σ eff using the star's geometrical cross section, ∼ R 2 , whereas the magnetic field extends far beyond the boundary of the star and scales like B ∼ r −3 for a magnetic dipole. Third, depending on the nature of the observation, it may be necessary to integrate over a finite region of the sky, such as toward the galactic center, which could contain many neutron stars, further increasing the encounter rate [136]. Fourth, the fiducial axion star mass M sol = 10 9 kg is a free parameter, and a smaller value implies a larger encounter rate.…”

Section: Compact Starsmentioning

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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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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Section: Compact Starsmentioning

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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“…Another possibility is that ALPs may be converted into radio photons via the Primakoff effect [128]. This process requires strong magnetic fields, making the magnetospheres of neutrons stars (NSs) a promising environment for this axionphoton conversion [129][130][131]. Around intermediate mass black holes (IMBHs), the DM density is expected to be significantly enhanced (see Sec.…”

Section: Ultralight Bosonsmentioning

confidence: 99%

Gravitational wave probes of dark matter: challenges and opportunities

Bertone

Croon²,

Amin

et al. 2020

SciPost Phys. Core

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In this white paper, we discuss the prospects for characterizing and identifying dark matter using gravitational waves, covering a wide range of dark matter candidate types and signals. We argue that present and upcoming gravitational wave probes offer unprecedented opportunities for unraveling the nature of dark matter and we identify the most urgent challenges and open problems with the aim of encouraging a strong community effort at the interface between these two exciting fields of research.

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“…4 and 5), and also a spike profile ("NSM Spike") which would lead to stronger bounds. We note, however, that the sensitivity of such a search to ALP parameters strongly depends on neutron star modelling and the telescope used [112]. At large ALP masses the intensity line-mapping experiment SPHEREx [113] will be able to probe to the bottom of the kination region.…”

Section: Fig 4 Theoretical Targets (Colored Bands)mentioning

confidence: 99%

Dark matter targets for axionlike particle searches

et al. 2019

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Many existing and proposed experiments targeting QCD axion dark matter (DM) can also search for a broad class of axionlike particles (ALPs). We analyze the experimental sensitivities to electromagnetically coupled ALP DM in different cosmological scenarios with the relic abundance set by the misalignment mechanism. We obtain benchmark DM targets for the standard thermal cosmology, a pre-nucleosynthesis period of early matter domination, and a period of kination. These targets are theoretically simple and assume Oð1Þ misalignment angles, avoiding fine-tuning of the initial conditions. We find that some experiments will have sensitivity to these ALP DM targets before they are sensitive to the QCD axion, and others can potentially reach interesting targets below the QCD band. The ALP DM abundance also depends on the origin of the ALP mass. Temperature-dependent masses that are generated by strong dynamics (as for the QCD axion) correspond to DM candidates with smaller decay constants, resulting in even better detection prospects.

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Detecting axion dark matter with radio lines from neutron star populations

Cited by 125 publications

References 111 publications

Dipole radiation and beyond from axion stars in electromagnetic fields

Dipole radiation and beyond from axion stars in electromagnetic fields

Gravitational wave probes of dark matter: challenges and opportunities

Dark matter targets for axionlike particle searches

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