Structure Formation and Microlensing with Axion Miniclusters

Abstract

If the symmetry breaking responsible for axion dark matter production occurs during the radiation-dominated epoch in the early Universe, then this produces large amplitude perturbations that collapse into dense objects known as axion miniclusters. The characteristic minicluster mass, $M_0$, is set by the mass inside the horizon when axion oscillations begin. For the QCD axion $M_0\sim 10^{-10}{M}_{\odot }$, however for an axion-like particle $M_0$ can approach $M_{\odot }$ or higher. Using the Press-Schechter formalism we compute the mass function of halos formed by hierarchical structure formation from these seeds. We compute the concentrations and collapse times of these halos and show that they can grow to be as massive as $10^6{M}_0$. Within the halos, miniclusters likely remain tightly bound, and we compute their gravitational microlensing signal taking the fraction of axion dark matter collapsed into miniclusters, $f_{\mathrm{MC}}$, as a free parameter. A large value of $f_{\mathrm{MC}}$ severely weakens constraints on axion scenarios from direct detection experiments. We take into account the non-Gaussian distribution of sizes of miniclusters and determine how this effects the number of microlensing events. We develop the tools to consider microlensing by an extended mass function of non-point-like objects, and use microlensing data to place the first observational constraints on $f_{\mathrm{MC}}$. This opens a new window for the potential discovery of the axion.

27 pages, 23 figures, follow up paper to 1701.04787. v2 matches published version. Appendix added on non-Gaussian effects, discussion extended

References in corpus (29)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• Ultralight scalars as cosmological dark matter
• Cosmic Structure as the Quantum Interference of a Coherent Dark Wave
• Limits on the Macho Content of the Galactic Halo from the EROS-2 Survey of the Magellanic Clouds
• Understanding the Core-Halo Relation of Quantum Wave Dark Matter, $\psi$DM, from 3D Simulations
• A search for ultra-light axions using precision cosmological data
• Dielectric Haloscopes: A New Way to Detect Axion Dark Matter
• Galaxy Formation with BECDM: I. Turbulence and relaxation of idealised haloes
• Axion dark matter, solitons, and the cusp-core problem
• Effects of Scale-Dependent Non-Gaussianity on Cosmological Structures
• Resonant detection of axion mediated forces with Nuclear Magnetic Resonance
• The Excursion Set Theory of Halo Mass Functions, Halo Clustering, and Halo Growth
• Discreteness effects in simulations of Hot/Warm dark matter
• Redefining the Axion Window
• Microlensing and dynamical constraints on primordial black hole dark matter with an extended mass function
• A Clockwork Theory
• Relativistic axions from collapsing Bose stars
• Galaxy UV-luminosity function and reionization constraints on axion dark matter
• The Quest for an Intermediate-Scale Accidental Axion and Further ALPs
• Fast Radio Bursts and Axion Miniclusters
• Astrophysical Effects of Scalar Dark Matter Miniclusters
• Cosmological particle-in-cell simulations with ultralight axion dark matter
• Substructure of fuzzy dark matter haloes
• Axion Stars and Fast Radio Bursts
• Axion astronomy with microwave cavity experiments
• Miniclusters in the Axiverse
• Nonlinear evolution of dark matter subhalos and applications to warm dark matter
• Hydrogen Axion Star: Metallic Hydrogen Bound to a QCD Axion BEC
• Axion Stars and Repeating Fast Radio Bursts with Finite Bandwidths

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• Subaru through a different lens: microlensing by extended dark matter structures
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• Lightish but clumpy: scalar dark matter from inflationary fluctuations
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• Probing axion dark matter with 21cm fluctuations from minihalos
• A forecast of the sensitivity of the DALI Experiment to Galactic axion dark matter
• Cosmic microwave background constraints on extended dark matter objects
• Optical Lensing by Axion Stars: Observational Prospects with Radio Astrometry
• Astrophysical Searches and Constraints on Ultralight Bosonic Dark Matter
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• Can QCD Axion Stars explain Subaru HSC microlensing?
• Gravitational Wave Resonance in Ultra-Light Dark Matter Halos
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• A Faster Growth of Perturbations in an Early Matter Dominated Epoch: Primordial Black Holes and Gravitational Waves
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