{
  "abstract": "The puzzling bimodality displayed by blazars on the broad-band spectral indices ($α_{\\rm ro}-α_{\\rm ox}$) plane is still an open question. To investigate its physical origin, we compiled a sample comprising 136 flat-spectrum radio quasars (FSRQs), 64 low-synchrotron-peaked BL Lac objects (LBLs), 39 intermediate-synchrotron-peaked BL Lac objects (IBLs), and 105 high-synchrotron-peaked BL Lac objects (HBLs). Our results show that (FSRQs+LBLs)$\\rightarrow$IBLs$\\rightarrow$HBLs follow a \\reflectbox{$\\angle$}-shaped evolutionary sequence on the $α_{\\rm ro}-α_{\\rm ox}$ plane, with the average 5\\,GHz radio Doppler factor, jet power, and accretion Eddington ratio decreasing along this \\reflectbox{$\\angle$}-shaped track. Additionally, the distributions of $α_{\\rm ox}$ exhibit only slight differences among blazar subclasses, whereas those of $α_{\\rm ro}$ and $α_{\\rm rx}$ differ significantly. Our results can be naturally explained if the distribution of blazars on the $α_{\\rm ro}-α_{\\rm ox}$ plane is regulated by the accretion rates and the Doppler beaming effect across different bands ($δ_i^{q_i}/δ_j^{q_j}$). However, $δ_i/δ_j$ plays a pivotal role in the distribution, while jet shape ($q=2(3)+α_ν$) and spectral indices ($α_ν$) play a minor role. Our results suggest that FSRQs+LBLs are strong-jet sources coupled with radiatively efficient accretion, and their jets are accelerated to a larger distance from the core and still maintain relativistic speeds down to the radio region; HBLs are weak-jet sources coupled with radiatively inefficient accretion, and their jets may begin to decelerate in the optical region and exhibit sub-relativistic speeds as they propagate to the radio region. IBLs are regarded as transitional objects between FSRQs+LBLs and HBLs.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.03435",
  "author_total": 1,
  "authors": [
    {
      "name": "Qingchen Long"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/fhk29jrdd02tk.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.03435",
  "fulltext_url": null,
  "id": "fhk29jrdd02tk",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.03435",
  "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.HE"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2609.03435",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-03",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/fhk29jrdd02tk.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:31Z",
      "native_id": "2609.03435",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.03435"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    }
  ],
  "title": "The Jet Properties and Accretion Regime for the Blazar Sequence",
  "title_text": "The Jet Properties and Accretion Regime for the Blazar Sequence",
  "type": "preprint",
  "updated_at": "2026-10-30T12:18:31Z",
  "url": "https://research.draconitic.com/paper/fhk29jrdd02tk",
  "venue": "arXiv",
  "versions": []
}