{
  "abstract": "We propose time-domain astrometric weak lensing of multiply imaged quasars as a probe of substellar dark matter (DM) halos. In $Λ$CDM, each macro-image's light traverses many microhalos, producing a stochastic centroid motion with a calculable red power spectrum. Halos with crossing times longer than the survey impart a relative angular acceleration between image pairs. The response peaks at subhalo scale radii 0.005-2 pc and masses $3\\times10^{-6}$-$10^2\\,M_\\odot$, 12-14 orders of magnitude below the smallest detected DM structures, down to the damping cutoffs of a 100 GeV thermal relic. We forecast the sensitivity of ten-year campaigns with 300 epochs for two benchmark systems: the galaxy-lensed quadruple B1422+231 at a 0.1 $μ$as per-epoch precision forecast for extended-path intensity correlation, and the cluster-lensed triple SDSS J1029+2623 at 1 $μ$as. The angular-acceleration channel reaches the standard $Λ$CDM microhalo population with a variance signal-to-noise ratio of order ten for the galaxy lens (order unity after stellar microlensing subtraction) and 0.35 for the cluster under the optimistic assumption that 10% of the projected mass density at the image positions resides in surviving microhalos. A positive detection would: raise universal lower bounds on the DM particle mass to $\\gtrsim400$ keV for fermions and $\\gtrsim10^{-12}$ eV for bosons; constrain the DM kinetic decoupling temperature to $\\gtrsim 10$ MeV; and be sensitive to the running of the spectral tilt at the 0.01 level over 15-20 e-folds of the primordial curvature power spectrum. A robust null result across well-characterized lenses would constrain microhalo survival and/or imply violations of the above inequalities. These signatures motivate differential astrometric observations with extreme 0.1-1 $μ$as light-centroiding precision on multiply imaged quasars. [Abridged]",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2608.27557",
  "author_total": 2,
  "authors": [
    {
      "name": "Ken Van Tilburg"
    },
    {
      "name": "David E. Kaplan"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/fv315q8ydpgbv.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.27557",
  "fulltext_url": null,
  "id": "fv315q8ydpgbv",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.27557",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.CO"
    ],
    [
      "arxiv",
      "astro-ph.GA"
    ],
    [
      "arxiv",
      "hep-ph"
    ],
    [
      "openalex",
      "3106|Dark Matter and Cosmic Phenomena"
    ]
  ],
  "openalex": "W7204844064",
  "pdf_url": "https://arxiv.org/pdf/2608.27557",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-02",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/fv315q8ydpgbv.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:26:45Z",
      "native_id": "2608.27557",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.27557"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "physics",
      "origin": "arxiv:hep-ph",
      "subfield": "high-energy"
    }
  ],
  "title": "Discovering Substellar Dark Matter Halos with Astrometric Weak Lensing of Multiply Imaged Quasars",
  "title_text": "Discovering Substellar Dark Matter Halos with Astrometric Weak Lensing of Multiply Imaged Quasars",
  "type": "preprint",
  "updated_at": "2026-10-30T12:26:45Z",
  "url": "https://research.draconitic.com/paper/fv315q8ydpgbv",
  "venue": "arXiv",
  "versions": []
}