{
  "abstract": "Ultra-compact AM CVn binaries in the high-state of stable mass transfer ($\\dot{M}\\gtrsim10^{-9}M_\\odot/\\rm{yr}$) are expected to be among the loudest persistent sources for upcoming space-based GW observatories. These systems typically have orbital periods $P_{\\rm{orb}}\\lesssim30$ minutes. We present a systematic search for high-state AM CVn binaries in the Milky Way by targeting a region within the Gaia color-magnitude diagram, combined with ZTF time-domain photometry. We focus on variable targets within that sample with 5-30 minute periods. Our survey discovered three new high-state AM CVn binaries (ZTF J1840-1742, ZTF J2007-0527 and ZTF J2111+3158) with orbital periods of 16.86, 18.63, and 16.71 minutes, and recovered three known systems. We obtain high-speed photometry and phase-resolved spectroscopy to confirm their nature. Their spectra show helium emission lines with no detectable hydrogen. In two targets, the lines are double-peaked, and Doppler tomograms confirm an accretion disk. We estimate mass accretion rates of $\\sim10^{-9}M_\\odot/\\rm{yr}$, and $3σ$ X-ray luminosity upper limits of $\\sim10^{33}\\rm{erg/s}$. Based on this sample, we infer a local space density of high-state AM CVn population in the Milky Way of $\\sim(1.0-2.7)\\times10^{-8}\\rm{pc}^{-3}$ (for disk scale heights $h_z=300-200$ pc), representing 2-5% of the total Galactic AM CVn density. Their birth rate, $\\sim(2.4-4.3)\\times10^{-4}\\rm{yr}^{-1}$ (for $h_z=300-200$ pc), is consistent with the total AM CVn birth rate, implying most systems entering the high-state phase survive and evolve to longer orbital periods. This local space density suggests LISA and TianQin will detect about 36% and 19% of the total Galactic population, respectively, during their nominal 4-yr missions ($S/N\\ge5$). The Vera C. Rubin Observatory's LSST will detect about 34-44% of these systems over its 10-yr survey ($m_r\\lesssim26.9$ mag).",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2608.04179",
  "author_total": 12,
  "authors": [
    {
      "name": "Ilkham Galiullin"
    },
    {
      "name": "Antonio C. Rodriguez"
    },
    {
      "name": "Kareem El-Badry"
    },
    {
      "name": "Valery Suleimanov"
    },
    {
      "name": "Vladislav Dodon"
    },
    {
      "name": "Askar Sibgatullin"
    },
    {
      "name": "Warren R. Brown"
    },
    {
      "name": "Kevin Burdge"
    },
    {
      "name": "Jan van Roestel"
    },
    {
      "name": "Edo Berger"
    },
    {
      "name": "V. Ashley Villar"
    },
    {
      "name": "Ilaria Caiazzo"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/3bmh27dg2hnnx.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.04179",
  "fulltext_url": null,
  "id": "3bmh27dg2hnnx",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.04179",
  "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.GA"
    ],
    [
      "arxiv",
      "astro-ph.HE"
    ],
    [
      "arxiv",
      "astro-ph.SR"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2608.04179",
  "pmcid": null,
  "pmid": null,
  "published": "2026-08-04",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/3bmh27dg2hnnx.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:25:12Z",
      "native_id": "2608.04179",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.04179"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.SR",
      "subfield": "stellar"
    }
  ],
  "title": "A survey of ultra-compact high-state AM CVn binaries with ZTF and Gaia: New discoveries and observational constraints on Galactic space density",
  "title_text": "A survey of ultra-compact high-state AM CVn binaries with ZTF and Gaia: New discoveries and observational constraints on Galactic space density",
  "type": "preprint",
  "updated_at": "2026-10-30T12:25:12Z",
  "url": "https://research.draconitic.com/paper/3bmh27dg2hnnx",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.1051/0004-6361/202660872",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}