ANGULAR MOMENTUM ACQUISITION IN GALAXY HALOS
- Department of Natural and Mathematical Sciences, California Baptist University, 8432 Magnolia Ave., Riverside, CA 92504 (United States)
- Department of Astronomy, University of Wisconsin-Madison, 475 N. Charter St., Madison, WI 53706 (United States)
- Center for Cosmology, Department of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697 (United States)
- Department of Physics, New York City College of Technology, 300 Jay St., Brooklyn, NY 11201 (United States)
- Institute for Theoretical Physics, University of Zurich, 8057, Zurich (Switzerland)
- Department of Physics and Astronomy, McMaster University, Main Street West, Hamilton L85 4M1 (Canada)
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
We use high-resolution cosmological hydrodynamic simulations to study the angular momentum acquisition of gaseous halos around Milky-Way-sized galaxies. We find that cold mode accreted gas enters a galaxy halo with {approx}70% more specific angular momentum than dark matter averaged over cosmic time (though with a very large dispersion). In fact, we find that all matter has a higher spin parameter when measured at accretion than when averaged over the entire halo lifetime, and is well characterized by {lambda} {approx} 0.1, at accretion. Combined with the fact that cold flow gas spends a relatively short time (1-2 dynamical times) in the halo before sinking to the center, this naturally explains why cold flow halo gas has a specific angular momentum much higher than that of the halo and often forms ''cold flow disks.'' We demonstrate that the higher angular momentum of cold flow gas is related to the fact that it tends to be accreted along filaments.
- OSTI ID:
- 22126609
- Journal Information:
- Astrophysical Journal, Vol. 769, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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