{
  "abstract": "We measured the proper motion dipole of quasars observed by \\textit{Gaia} to determine the acceleration of the Solar System with respect to the quasar rest frame. We characterised the full angular power spectrum of the proper motion field using the pseudo-$C_\\ell$ formalism and employed simulation-based inference to jointly constrain the dipole and higher multipole power. Cross-correlation with the \\textit{Gaia} scanning strategy, stellar density and stellar proper motion maps was used to diagnose the origin of systematic power beyond the dipole. We applied this framework to both the \\textit{Gaia} EDR3 quasar catalogue and the Quaia catalogue. The inferred acceleration is consistent with the previous determination, but the credible intervals widen by factors of 1.5 to 5 when higher-multipole degeneracies are properly marginalised, indicating that previous uncertainty estimates were optimistic. Our best estimate, based on the Quaia catalogue, is ($g_x,\\,g_y,\\,g_z$) = $\\left(1.01^{+0.72}_{-0.72}, \\,-4.94^{+0.54}_{-0.55},\\,-2.13^{+0.58}_{-0.58}\\right) \\;\\rm μas \\,yr^{-1}$. This corresponds to an amplitude of $5.55_{-0.53}^{+0.54}\\,\\rm \\;μas\\,yr^{-1}$, where $\\mathbf{g} = \\mathbf{a}/c$ is the Solar System acceleration expressed as a proper motion drift in equatorial coordinates. The inferred acceleration is directed towards $(l,\\, b) = \\left(11.71^{+7.0}_{-6.8},\\, -9.01^{+7.0}_{-6.9}\\right)^\\circ$, equivalently $(α,\\, δ) = \\left(281.39^{+7.8}_{-8.0},\\, -22.93^{+6.5}_{-6.2}\\right)^\\circ$. This is in good agreement with a Galactic centre--dominated acceleration. The acceleration components show no significant dependence on source redshift, providing further evidence of the acceleration's kinematic origin.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2605.30367",
  "author_total": 2,
  "authors": [
    {
      "name": "Phu Huy Nguyen"
    },
    {
      "name": "Calum Murray"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/8e5qyh2qnmzsr.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2605.30367",
  "fulltext_url": null,
  "id": "8e5qyh2qnmzsr",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2605.30367",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.CO"
    ],
    [
      "arxiv",
      "astro-ph.GA"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2605.30367",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-09",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/8e5qyh2qnmzsr.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:28:36Z",
      "native_id": "2605.30367",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2605.30367"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "Observing the Peculiar Acceleration of our Solar System with Quasar Proper Motions",
  "title_text": "Observing the Peculiar Acceleration of our Solar System with Quasar Proper Motions",
  "type": "preprint",
  "updated_at": "2026-10-30T12:28:36Z",
  "url": "https://research.draconitic.com/paper/8e5qyh2qnmzsr",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.1051/0004-6361/202660989",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}