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Structural and scaling properties of galaxy clusters Probing the physics of structure formation

Structural and scaling properties of galaxy clusters Probing the physics of structure formation. M.Arnaud, G.Pratt, E.Pointecouteau (CEA-Sap Saclay). • Dark matter distribution in clusters with XMM E.Pointecouteau • Some insights into cluster gas physics with XMM G.Pratt

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Structural and scaling properties of galaxy clusters Probing the physics of structure formation

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  1. Structural and scaling properties of galaxy clusters Probing the physics of structure formation M.Arnaud, G.Pratt, E.Pointecouteau (CEA-Sap Saclay) • Dark matter distribution in clusters with XMM E.Pointecouteau • Some insights into cluster gas physics with XMM G.Pratt • Cluster evolution M.Arnaud

  2. Coma z =0.02 A1795 z=0.06 XMM XMM RXJ1053 z =1.26 RXJ0848 z=1.27 XMM Chandra The cluster population: A large variety of objects • • Physical parameters • Lbol ~1041 - a few 1046 ergs/s • Mtot ~1013 - a few 1015 Mo • T ~ 0.3 - 15 keV • • Present at least since z ~ 1.5 • • Morphology: • regular (~50%) but some not • ≠ dynamical state at all z

  3. A2319 T= 9.1 keV A 2657 T=3.7 keV RI Sx profile kT [Neumann & Arnaud 1999] [Mohr & Evrard 1997] But all possible clusters do NOT exist  Correlations  Some regularity in shape

  4. Z=0 Z=0.5 Z=1 Canonical model of cluster formation (anal. spherical collapse; num simul) • ICM: evolving in the gravitational potential of the DM: fgas = cst • Clusters collapsed at z correspond to a fixed density contrast: GM/R3 = <r> =d rc (z) ; d~200 • Are close to virial/hydrostatic equilibrium (between big mergers) kT a GM/R • Have same internal DM (and thus gas) structure Self Similarity of the cluster population expected Universal profiles  Simple scaling laws: Q  Ta M  T3/2 Rv T1/2 LX T2 [Bryan & Norman 1998] log(r/ rc) [NFW 1995] Comparison with observations  test of formation physics

  5. 2 - Spectroscopy  temperature profile Spherical symmetry + Hydrostatic Equilibrium Total mass profile From XMM observations to DM profiles • 1 – Imaging •  surface brightness profile • density profile Chandra match XMM!

  6. - down to 0.01 virial radius - up to 0.7 virial radius Mass profile derived from the HE equation • A1413 [Pratt & Arnaud 02] • z=0.143 ; kTX=6.49 keV • A1983 [Pratt & Arnaud 03] • z=0.044 ; kTX=2.3 keV • A478 [Pointecouteau et al. 03] • z=0.088 ; kTX=6.73 keV • deprojection • PSF correction • Cusped profile as expected from num. Simu. (NFW profile preferred) •  Similarity observed in the shape of M(r)

  7. XMM on 3 relaxed cooling flow clusters :M  T1.49±0.2  Normalisation offset at d = 2500 (0.3 r200 )… and at all radii (d) At a given R corresponding to a density constrast d : Md = ad T3/2 ad depends on the (universal) gas and DM distribution, via HE The M-T relation from XMM/chandra d = 2500 (0.3 r200 ) Chandra on 5 relaxed hot/lensing clusters :M  T1.52±0. 36 Modelling of DM collapse OK; Pb in gas modelling (distribution shape)

  8. Conclusion XMM-Newton  Unpreecedent accuracy on kT(r)  First detailed DM profiles for clusters (up to Rv) Similarity in the dark matter shape of cluster  Dark matter collapse seems to be well understood  Better constraints needed to characterize the central region:  NFW preferred  ideal world: XMM+Chandra Departure from predicted M-T relation normalisation  Modelling of the gas still not reproducing real clusters  Physics of the gas not well understood (G.Pratt)  Evolution of scaling properties with z (M.Arnaud)

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