Baryons in the warm-hot intergalactic medium

Romeel Davé, Renyue Cen, Jeremiah P. Ostriker, Greg L. Bryan, Lars Hernquist, Neal Katz, David H. Weinberg, Michael L. Norman, Brian O'Shea

Research output: Contribution to journalArticlepeer-review

646 Scopus citations


Approximately 30%-40% of all baryons in the present-day universe reside in a warm-hot intergalactic medium (WHIM), with temperatures in the range 105 < T < 107 K. This is a generic prediction from six hydrodynamic simulations of currently favored structure formation models having a wide variety of numerical methods, input physics, volumes, and spatial resolutions. Most of these warm-hot baryons reside in diffuse large-scale structures with a median overdensity around 10-30, not in virialized objects such as galaxy groups or galactic halos. The evolution of the WHIM is primarily driven by shock heating from gravitational perturbations breaking on mildly nonlinear, nonequilibrium structures such as filaments. Supernova feedback energy and radiative cooling play lesser roles in its evolution. WHIM gas may be consistent with observations of the 0.25 keV X-ray background without being significantly heated by nongravitational processes because the emitting gas is very diffuse. Our results confirm and extend previous work by Cen & Ostriker and Davé et al.

Original languageEnglish (US)
Pages (from-to)473-483
Number of pages11
JournalAstrophysical Journal
Issue number2 PART 1
StatePublished - May 10 2001


  • Cosmology: observations
  • Intergalactic medium
  • Large-scale structure of universe
  • Methods: numerical

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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