{
  "$schema": "./item.schema.json",
  "id": "potamides-apj",
  "type": "publication",
  "cvs": [
    "np",
    "2page",
    "1page"
  ],
  "date": {
    "start": "2026-05"
  },
  "title": "Potamides: Mapping Dark Matter Halo Shapes from Stellar Stream Tracks in the Local Universe",
  "shortTitle": "Potamides: Halo Shapes from Stream Curvature",
  "nickTitle": "Potamides",
  "status": "accepted",
  "entryType": "article",
  "authors": [
    {
      "family": "Wu",
      "given": "Sirui",
      "student": "graduate",
      "orcid": "0009-0003-4675-3622"
    },
    {
      "family": "Starkman",
      "given": "Nathaniel",
      "me": true,
      "orcid": "0000-0003-3954-3291"
    },
    {
      "family": "Pearson",
      "given": "Sarah",
      "orcid": "0000-0003-0256-5446"
    },
    {
      "family": "Nibauer",
      "given": "Jacob",
      "orcid": "0000-0001-8042-5794"
    },
    {
      "family": "Miro-Carretero",
      "given": "Juan",
      "orcid": "0000-0003-1808-1753"
    },
    {
      "family": "Martinez-Delgado",
      "given": "David",
      "orcid": "0009-0004-1061-7802"
    }
  ],
  "venue": {
    "journal": "The Astrophysical Journal"
  },
  "arxiv": "2605.07809",
  "bibcode": "2026arXiv260507809W",
  "tags": [
    "extragalactic",
    "streams",
    "dark-matter",
    "dynamics"
  ],
  "citekey": "Wu+:2026:potamides-halo-shapes",
  "abstract": "Stellar streams trace the gravitational potential of their host galaxies and offer a direct probe of dark matter halo geometry. Cosmological simulations predict that halo shapes depend on both baryonic physics and the nature of dark matter, yet observational constraints on halo flattening and orientation remain limited, especially for individual galaxies. We present Potamides, which utilizes the curvature of extragalactic stellar streams to derive constraints on halo shapes. We apply Potamides to 15 stellar streams from the Stellar Stream Legacy Survey to infer the projected axis ratios and orientation of their host halos. We find that some streams in our sample exclude large regions of halo flattenings and halo orientations. Systems with edge-on wrapping loops or sharp turning points yield the strongest constraints, whereas great circle-like streams remain largely uninformative. All streams in our sample support a spherical halo for a given flattening direction. These results demonstrate that stream morphology can provide halo shape constraints for individual external galaxies. With upcoming surveys (such as Euclid, Rubin, Roman, and ARRAKIHS) expected to discover large numbers of stellar streams, this curvature-based technique will enable rapid statistical tests of dark matter and baryonic physics through the shapes and alignments of halos and disks across cosmic time.",
  "highlight": {
    "topic": "extragalactic",
    "image": "highlights/potamides-apj.webp",
    "alt": "The galaxy ESO 186-063 seen edge-on, with its faint stellar stream fitted as a curved track. Arrows show the stream’s curvature, and the track is shaded by how often each point rejects a trial halo potential, over that potential’s equipotential contours.",
    "description": "A stellar stream’s curvature traces the pull of its host’s dark matter halo. Applied to 15 streams from the Stellar Stream Legacy Survey, Potamides constrains each halo’s projected flattening and orientation. Streams with edge-on loops or sharp turns constrain it most, great-circle-like ones barely at all, and three hint that the stellar disk shapes the inner gravitational field. Led by Sirui Wu."
  }
}