Ram pressure stripping of the large magellanic cloud's disk as a probe of the milky way's circumgalactic medium

Munier Salem, Gurtina Besla, Greg Bryan, Mary Putman, Roeland P. Van Der Marel, Stephanie Tonnesen

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112 Scopus citations


Recent observations have constrained the orbit and structure of the Large Magellanic Cloud (LMC), implying a well-constrained pericentric passage about the Milky Way (MW) ∼50 Myr ago. In this scenario, the LMC's gaseous disk has recently experienced stripping, suggesting the extent of its HI disk directly probes the medium in which it is moving. From the observed stellar and HI distributions of the system we find evidence of a truncated gas profile along the windward "leading edge" of the LMC disk, despite a far more extended stellar component. We explore the implications of this ram pressure stripping signature, using both analytic prescriptions and full three-dimensional hydrodynamic simulations of the LMC. Our simulations can match the radial extent of the LMC's leading (windward) edge only in scenarios where the MW CGM density at pericentric passage is np (R = 48.2 ± 5 kpc) = 1.1-.45+.44 × 10-4 cm-3. The implied pericentric density proves to be insensitive to both the broader CGM and temperature profiles, thus providing a model-independent constraint on the local gas density. This result imposes an important constraint on the density profile of the MW's CGM at 50 kpc, and thus also on the total baryon content of the MW. From our work, assuming a β-profile valid to ∼rvir, we infer a total diffuse CGM mass M (300 kpc) = 2.7 ± 1.4 × 1010M or approximately 15% of a 1012M MW's baryonic mass budget.

Original languageEnglish (US)
Article number77
JournalAstrophysical Journal
Issue number1
StatePublished - Dec 10 2015


  • Galaxy: structure
  • Magellanic Clouds
  • hydrodynamics
  • intergalactic medium

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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