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