{
  "abstract": "The properties of compact stars with a strong first-order phase transition to quark matter and with an additional fluid of self-interacting bosonic dark matter (DM) are studied. We find that the inclusion of DM changes the stability of mass-radius configurations relative to the naive one-fluid criterion. For compact star configurations with similar masses and different radii, so-called twin stars, the presence of DM removes the unstable segment between the hadronic and the hybrid branch, so that the stable mass-radius sequence becomes continuous after the onset of the phase transition to quark matter. We furthermore find stable ultra-compact objects (UCOs), defined by a total compactness $C = M_\\text{tot}/R_\\text{grav} \\ge 1/3$. We observe two distinct classes of UCOs: a DM-halo class with $f_\\text{DM} \\gtrsim 0.9$, and a DM-core class at $f_\\text{DM} \\lesssim 0.02$. The two classes can be separated by the surface redshift of the normal matter, which reaches $z = 0.734 - 0.808$ for the DM-core and extreme values of $z = 2 - 3.468$ for the DM-halo class, allowing us to use their redshift as a way to disentangle the two classes. Furthermore, the high redshift of the DM-halo UCOs could serve as a signal of DM since their redshift exceeds the Buchdahl limit of $z = 2$. Finally, we find hybrid star solutions of ``ultimate twins\" with similar masses and visible radii, but different dark matter content, leading to different tidal deformabilities and surface redshifts. Future X-ray and gravitational measurements of ultra-compact neutron stars with radii and masses outside the allowed neutron star range can thereby probe the presence and the properties of DM in addition to a first-order phase transition to quark matter.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.03964",
  "author_total": 3,
  "authors": [
    {
      "name": "Ishfaq Ahmad Rather"
    },
    {
      "name": "Sarah Louisa Pitz"
    },
    {
      "name": "Jürgen Schaffner-Bielich"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/aqntm4cf8wrax.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.03964",
  "fulltext_url": null,
  "id": "aqntm4cf8wrax",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.03964",
  "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.HE"
    ],
    [
      "arxiv",
      "hep-ph"
    ],
    [
      "arxiv",
      "nucl-th"
    ],
    [
      "openalex",
      "3103|Pulsars and Gravitational Waves Research"
    ]
  ],
  "openalex": "W7208761377",
  "pdf_url": "https://arxiv.org/pdf/2609.03964",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-26",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/aqntm4cf8wrax.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:35:35Z",
      "native_id": "2609.03964",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.03964"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    },
    {
      "field": "physics",
      "origin": "arxiv:hep-ph",
      "subfield": "high-energy"
    },
    {
      "field": "physics",
      "origin": "arxiv:nucl-th",
      "subfield": "nuclear"
    }
  ],
  "title": "Ultra-compact twin stars with hybrid equations of state from bosonic dark matter",
  "title_text": "Ultra-compact twin stars with hybrid equations of state from bosonic dark matter",
  "type": "preprint",
  "updated_at": "2026-10-30T12:35:35Z",
  "url": "https://research.draconitic.com/paper/aqntm4cf8wrax",
  "venue": "arXiv",
  "versions": []
}