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The Effect of Sloshing Gas on Hydrostatic Mass Profiles
SNOWCLUSTER Workshopby Ryan E. Johnson
CfA, Dartmouth College
with
Christine Jones, Maxim Markevitch, Bill Forman, John Zuhone & Gary Wegner
Outline
Hydrostatic Mass Estimates Sloshing (observations & simulations) Analysis of Simulated Sloshing
− HE mass profiles Conclusions
Hydrostatic Equilibrium
− Radial derivatives of T and problems with discontinuities and flat profiles
− Non-thermal pressure support
Hydrostatic Mass Estimates
RXJ1720.1+2638 (Mazzotta et al. 2001) Abell 1795 (Markevitch et al. 2001)
− Keshet et al. (2010)
Gas Sloshing
Sloshing occurs when a cluster is gravitationally perturbed
Hydro simulations (R=20, b=1 Mpc, with gas)
Gas Sloshing
Sloshing occurs when a cluster is gravitationally perturbed
Hydro simulations (R=20, b=1 Mpc, with gas)
Zuhone et al. (2010)
Sloshing Type Cold Fronts Characteristics
− Contact discontinuities: T and are discontinuous, P is continuous
− Appear as spiral shape (Lagana et al. 2010) or concentric edges in Sx
− Simulations show weak interactions may induce sloshing (Ascasibar & Markevitch, 2006)
Simulations
Ascasibar & Markevitch (2006)
− GADGET 2 SPH code
− T=10 keV, MT=1.7e15 M⊙,
Hernquist DM profile− R=5, b=500 kpc− 10 kpc resolution
Projected temperature and density images
Simulations
Ascasibar & Markevitch (2006)
− GADGET 2 SPH code
− T=10 keV, MT=1.7e15 M⊙,
Hernquist DM profile− R=5, b=500 kpc− 10 kpc resolution
Projected temperature and density images
Fitting Simulations
Fitting with flexible analytic functions− Vikhlinin et al. (2006, V06)
Parameters were varied, the minimization was done to match projected functions to the images
Fitting Simulations
Sanity Check
Fitting Simulations
Fitting azimuthally averaged with V06
Fitting Across Sx Edges
Fitting Simulations
Fitting azimuthally averaged with V06
Fitting Across Sx Edges
Fitting Simulations
Fitting azimuthally averaged with V06
Fitting Across Sx Edges
Perfect Data - Perfect Functions
Differentiating the true azimuthally averaged T and
HE underestimates the true mass by 10-20% measured at outer edge and differs by 20-40% at the inner sloshing edge
Outer sloshing edge
Inner sloshing edge
Summary
Majority of our HE mass errors come from systematic effects:
− sparse sampling/inability to fit data
− choice of centers
Azimuthally averaging can compensate for some edges
Intrinsic deviation from HE mass estimates due to sloshing is relatively small and primarily at cold fronts
Thanks
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