{
  "abstract": "We study the relative contributions of mergers and accretion to the assembly of dark matter haloes within the framework of Excursion Set Theory (EST). We extend a variance-discretized merger-tree algorithm, which recursively reconstructs all branches of a complete merger tree and introduces a merger-ratio criterion for distinguishing mergers from accretion. The method is validated by comparing the resulting progenitor distributions with the analytical conditional first up-crossing distribution, showing excellent agreement over a wide range of halo masses and redshifts. We find that the accretion contribution depends strongly on the adopted merger-ratio threshold. For large merger ratios ($MR=0.1$--$0.25$), accretion accounts for up to $\\sim70\\%$ of the mass growth of massive haloes, whereas including all resolved mergers ($MR=10^{-6}$) reduces the accretion contribution to $\\sim40\\%$. These values are in good agreement with previous N-body simulation results. The accreted mass exhibits a nearly self-similar distribution in the mass-redshift plane, with the dominant contribution arising from progenitors in the range $10^{-3}M_0 \\lesssim M \\lesssim 10^{-1}M_0$ and predominantly at $0.5 \\lesssim z \\lesssim 2$. Our results demonstrate that EST-based merger trees provide an accurate and computationally efficient framework for investigating halo assembly and quantifying the relative roles of mergers and accretion in hierarchical structure formation.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.19312",
  "author_total": 1,
  "authors": [
    {
      "name": "Hamed Kameli"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/6dj0ys00ycyft.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.19312",
  "fulltext_url": null,
  "id": "6dj0ys00ycyft",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.19312",
  "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",
      "3103|Galaxies: Formation, Evolution, Phenomena"
    ]
  ],
  "openalex": "W7222058165",
  "pdf_url": "https://arxiv.org/pdf/2610.19312",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-13",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/6dj0ys00ycyft.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:29:31Z",
      "native_id": "2610.19312",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.19312"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "The Contribution of Mergers and Accretion to Dark Matter Halo Assembly: An Excursion Set Theory Approach",
  "title_text": "The Contribution of Mergers and Accretion to Dark Matter Halo Assembly: An Excursion Set Theory Approach",
  "type": "preprint",
  "updated_at": "2026-10-30T12:29:31Z",
  "url": "https://research.draconitic.com/paper/6dj0ys00ycyft",
  "venue": "arXiv",
  "versions": []
}