Axion minicluster streams in the solar neighbourhood

Abstract

A consequence of QCD axion dark matter being born after inflation is the emergence of small-scale substructures known as miniclusters. Although miniclusters merge to form minihalos, this intrinsic granularity is expected to remain imprinted on small scales in our galaxy, leading to potentially damaging consequences for the campaign to detect axions directly on Earth. This picture, however, is modified when one takes into account the fact that encounters with stars will tidally strip mass from the miniclusters, creating pc-long tidal streams that act to refill the dark matter distribution. Here we ask whether or not this stripping rescues experimental prospects from the worst-case scenario in which the majority of axions remain bound up in unobservably small miniclusters. We find that the density sampled by terrestrial experiment on mpc-scales will be, on average, around 70--90\% of the average local DM density, and at a typical point in the solar neighbourhood, we expect most of the dark matter to be comprised of debris from $\mathcal{O}(10^2$--$10^3)$ overlapping streams. If haloscopes can measure the axion signal with high-enough frequency resolution, then these streams are revealed in the form of an intrinsically spiky lineshape, in stark contrast with the standard assumption of a smooth, featureless Maxwellian distribution -- a unique prediction that constitutes a way for experiments to distinguish between pre and post-inflationary axion cosmologies.

5 + 9 pages, matches journal version

References in corpus (26)

• galpy: A Python Library for Galactic Dynamics
• Understanding the Core-Halo Relation of Quantum Wave Dark Matter, $\psi$DM, from 3D Simulations
• Dilute and dense axion stars
• Constraining the Galaxy's dark halo with RAVE stars
• The dark-matter axion mass
• A High Resolution Search for Dark-Matter Axions
• Dark matter local density determination: recent observations and future prospects
• Astrophysical Effects of Scalar Dark Matter Miniclusters
• Cosmology of axion dark matter
• Simulations of Axion Minihalos
• Axion minicluster power spectrum and mass function
• Axion astronomy with microwave cavity experiments
• On mini-halo encounters with stars
• Miniclusters in the Axiverse
• Transient Radio Signatures from Neutron Star Encounters with QCD Axion Miniclusters
• Imprints of the Early Universe on Axion Dark Matter Substructure
• Stellar Disruption of Axion Miniclusters in the Milky Way
• Simulations of axion-like particles in the post-inflationary scenario
• Structure of Axion Miniclusters
• Directional detection of dark matter streams
• Destruction of axion miniclusters in the Galaxy
• Soliton Formation and the Core-Halo Mass Relation: An Eigenstate Perspective
• Axion minivoids and implications for direct detection
• Soliton Merger Rates and Enhanced Axion Dark Matter Decay
• The Disruption of Dark Matter Minihalos by Successive Stellar Encounters
• Non-Virialized Axion Search Sensitive to Doppler Effects in the Milky Way Halo

Cited by in corpus (7)

• Near-quantum-limited axion dark matter search with the ORGAN experiment around 26 $\mu$eV
• Axion star condensation around primordial black holes and microlensing limits
• Searching for dark matter with a 1000 km baseline interferometer
• Axions in Andromeda: Searching for Minicluster -- Neutron Star Encounters with the Green Bank Telescope
• Ultimate light-shining-through-a-wall experiments to establish QCD axions as the dominant form of dark matter
• Search for Axionlike Dark Matter Using Liquid-State Nuclear Magnetic Resonance
• ADAMOS: Axion Daily Modulation Searches for Dark Matter at 20 GHz