The origin of polar ring galaxies: Evidence for galaxy formation by cold accretion

Andrea V. Macciò, Ben Moore, Joachim Stadel

Research output: Contribution to journalArticlepeer-review


Polar ring galaxies are flattened stellar systems with an extended ring of gas and stars rotating in a plane almost perpendicular to the central galaxy. We show that their formation can occur naturally in a hierarchical universe where most low-mass galaxies are assembled through the accretion of cold gas infalling along megaparsecscale filamentary structures. Within a large cosmological hydrodynamical simulation, we find a system that closely resembles the classic polar ring galaxy NGC 4650A. How galaxies acquire their gas is a major uncertainty in models of galaxy formation, and recent theoretical work has argued that cold accretion plays a major role. This idea is supported by our numerical simulations and the fact that polar ring galaxies are typically low-mass systems.

Original languageEnglish (US)
Pages (from-to)L25-L28
JournalAstrophysical Journal
Issue number1 II
StatePublished - Jan 1 2006


  • Cosmology: theory
  • Galaxies: formation
  • Methods: numerical

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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