{
  "abstract": "The radio/X-ray/black-hole-mass Fundamental Plane (FP) is widely used to estimate masses of accreting intermediate-mass black hole (IMBH) candidates. Its inverse use is justified only when radio luminosity traces a compact jet core and X-rays arise from the same sub-Eddington hard-state accretion flow. We formulate an accretion-state validity criterion for inverse-FP masses using verified BH X-ray binary radio/X-ray tracks as the empirical reference. Using 424 detections from 21 BHXBs and candidates, we find that both standard and curved tracks are present and the luminosity at which radio/X-ray behavior changes is source dependent. A low X-ray Eddington ratio is therefore not, by itself, sufficient to establish inverse-FP validity. Within a scale-invariant jet/hot-flow framework, track steepening reduces the effective mass leverage of the inversion, while at much lower accretion rates uncertainties in the dominant emission mechanism and compact-core production can invalidate the underlying FP assumptions altogether. We apply the criterion to representative IMBH-relevant systems without fitting a new plane. NGC 4395 is low-Eddington but compact-radio deficient: its VLA-scale and VLBI jet-base luminosities imply formal inverse-FP mass underestimates of about 1.0 and more than 2.8 dex if the deficit is misread as a mass signal. Globular-cluster X-ray populations in NGC 1399 and NGC 4472 are source-identity limited: 71% and 67% lie below $L_{\\rm Edd}(10\\,M_\\odot)$, and the high-luminosity tail alone does not identify an IMBH accretor. The radio non-detection of the $ω$ Centauri IMBH candidate constrains gas supply, accretion efficiency, and compact-core production rather than excluding the black hole. The resulting test defines which SKA/ngVLA-era radio cores can be converted into FP masses, and which instead constrain gas supply, source identity, or compact-core production.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.15960",
  "author_total": 3,
  "authors": [
    {
      "name": "Shahram Abbassi"
    },
    {
      "name": "Samik Mitra"
    },
    {
      "name": "Ramananda Santra"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/c4mwsda07vv7x.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.15960",
  "fulltext_url": null,
  "id": "c4mwsda07vv7x",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.15960",
  "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"
    ],
    [
      "openalex",
      "3103|Astrophysical Phenomena and Observations"
    ]
  ],
  "openalex": "W7213252726",
  "pdf_url": "https://arxiv.org/pdf/2609.15960",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-14",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/c4mwsda07vv7x.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:21:25Z",
      "native_id": "2609.15960",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.15960"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    }
  ],
  "title": "Validating Inverse Fundamental-Plane IMBH Mass Estimates in the SKA/ngVLA Era",
  "title_text": "Validating Inverse Fundamental-Plane IMBH Mass Estimates in the SKA/ngVLA Era",
  "type": "preprint",
  "updated_at": "2026-10-30T12:21:25Z",
  "url": "https://research.draconitic.com/paper/c4mwsda07vv7x",
  "venue": "arXiv",
  "versions": []
}