Simulations of axion minihalos

Xiao, Huangyu; Williams, Ian; McQuinn, Matthew

doi:10.1103/physrevd.104.023515

Cited by 60 publications

(48 citation statements)

References 83 publications

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“…14). On large scales, however, different patches of the universe would have been uncorrelated, and thus it is common to assume the statistics to be given by a white-noise power spectrum whose amplitude is set to match QCD axion simulations, and with a cut-off at modes that entered the horizon when the axions were relativistic (Xiao et al 2021).…”

Section: Axionsmentioning

confidence: 99%

Large-scale dark matter simulations

Angulo

Hahn

2022

Living Rev Comput Astrophys

111

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We review the field of collisionless numerical simulations for the large-scale structure of the Universe. We start by providing the main set of equations solved by these simulations and their connection with General Relativity. We then recap the relevant numerical approaches: discretization of the phase-space distribution (focusing on N-body but including alternatives, e.g., Lagrangian submanifold and Schrödinger–Poisson) and the respective techniques for their time evolution and force calculation (direct summation, mesh techniques, and hierarchical tree methods). We pay attention to the creation of initial conditions and the connection with Lagrangian Perturbation Theory. We then discuss the possible alternatives in terms of the micro-physical properties of dark matter (e.g., neutralinos, warm dark matter, QCD axions, Bose–Einstein condensates, and primordial black holes), and extensions to account for multiple fluids (baryons and neutrinos), primordial non-Gaussianity and modified gravity. We continue by discussing challenges involved in achieving highly accurate predictions. A key aspect of cosmological simulations is the connection to cosmological observables, we discuss various techniques in this regard: structure finding, galaxy formation and baryonic modelling, the creation of emulators and light-cones, and the role of machine learning. We finalise with a recount of state-of-the-art large-scale simulations and conclude with an outlook for the next decade.

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Section: Axionsmentioning

confidence: 99%

Large-scale dark matter simulations

Angulo

Hahn

2022

Living Rev Comput Astrophys

111

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“…The HMF at matter-radiation equality (at redshift z eq ) can be assessed by evolving the PQ field from the moment at which the PQ symmetry breaks until z eq [54,57]. The high-end tail of the HMF shows an exponential cutoff which, at recombination, is placed at around the largest mass of the AMCs, M max ðz eq Þ ≈ M 0 [54,78,79]. The characteristic mass M 0 is associated with the axion energy density contained within a Hubble horizon at t osc [80]…”

Section: B Initial Halo Mass Functionmentioning

confidence: 99%

Stellar disruption of axion miniclusters in the Milky Way

et al. 2021

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Axion miniclusters are dense bound structures of dark matter axions that are predicted to form in the postinflationary Peccei-Quinn symmetry breaking scenario. Although dense, miniclusters can easily be perturbed or even become unbound by interactions with baryonic objects such as stars. Here, we characterize the spatial distribution and properties of miniclusters in the Milky Way (MW) today after undergoing these stellar interactions throughout their lifetime. We do this by performing a suite of Monte Carlo simulations which track the miniclusters' structure and, in particular, accounts for partial disruption and mass loss through successive interactions. We consider two density profiles-Navarro-Frenk-White (NFW) and power-law (PL)-for the individual miniclusters in order to bracket the uncertainties on the minicluster population today due to their uncertain formation history. For our fiducial analysis at the solar position, we find a survival probability of 99% for miniclusters with PL profiles and 46% for those with NFW profiles. Our work extends previous estimates of this local survival probability to the entire MW. We find that towards the Galactic Center, the survival probabilities drop drastically. Although we present results for a particular initial halo mass function, our simulations can be easily recast to different models using the provided data and code (github.com/bradkav/axion-miniclusters). Finally, we comment on the impact of our results on lensing, direct, and indirect detection.

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“…If axion DM is bound into com- pact minihalos with M 1 M rather than a smooth distribution (see e.g. [38,39]), our signal is unlikely to be affected as the mass contained within our DM column is significantly greater than the mass of a minihalo and Poisson fluctuations are expected to be negligible in that limit. This is an advantage of this approach over terrestrial searches for local axion DM, since we are sensitive to the DM density over a larger spatial region and are therefore robust to local fluctuations in density.…”

Section: A Gegenschein From a Distant Point Sourcementioning

confidence: 91%

Axion dark matter-induced echo of supernova remnants

Sun,

Schutz,

Nambrath

et al. 2021

Preprint

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Axions are a theoretically promising dark matter (DM) candidate. In the presence of radiation from bright astrophysical sources at radio frequencies, nonrelativistic DM axions can undergo stimulated decay to two nearly back-to-back photons, meaning that bright sources of radio waves will have a counterimage ("gegenschein") in nearly the exact opposite spatial direction. The counterimage will be spectrally distinct from backgrounds, taking the form of a narrow radio line centered at ν = ma/4π with a width determined by Doppler broadening in the DM halo, ∆ν/ν ∼ 10 −3 . In this work, we show that the axion decay-induced echoes of supernova remnants may be bright enough to be detectable. Their non-detection may be able to set the strongest limits to date on axion DM in the ∼ 1 − 10 µeV mass range where there are gaps in coverage from existing experiments.

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Simulations of axion minihalos

Cited by 60 publications

References 83 publications

Large-scale dark matter simulations

Large-scale dark matter simulations

Stellar disruption of axion miniclusters in the Milky Way

Axion dark matter-induced echo of supernova remnants

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