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Amas de galaxies Emission non thermique comme traceur de la formation et de l’évolution

Amas de galaxies Emission non thermique comme traceur de la formation et de l’évolution. M. Arnaud CEA - Service d’astrophysique Saclay. A 1914. relic. LOFAR. SKA. halo. LS X-ray/radio emission: thermal and non-thermal components. Chandra Sun et al, 02.

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Amas de galaxies Emission non thermique comme traceur de la formation et de l’évolution

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  1. Amas de galaxies Emission non thermique comme traceur de la formation et de l’évolution M. Arnaud CEA - Service d’astrophysique Saclay

  2. A 1914 relic LOFAR SKA halo LS X-ray/radio emission: thermal and non-thermal components Chandra Sun et al, 02 VLA 1.4GHzClarke & Ensslin, 01 Bacchi et al 03 X-ray thermal - diffuse Radio synchrotron - diffuse - steep ( >1) Hot plasma(T~2-10 keV) Relativistic electrons(~1-100 Gev) Magnetic Field(0.1 - 1G) IC e- on CMB ⇒NT X-ray

  3. Origin and acceleration of the relativistic electrons? Jones et al, 03 • Ritchie & Thomas, 02 Cluster hierarchical formation => Shocks (heat the gas at Tvirial) • Radio halos/relics detected in un-relaxed (merger) clusters only • Problem: ~Mpc size but tlife ~107 - 108 years << tdiffusion ⇒Recent creation or (re) acceleration by a mechanism at cluster scale Several Models - Thermal electrons accelerated by shocks /turbulence - Non thermal electrons (from above or from AGN/Winds) re-accelerated - Secondary electrons from inelastic collisions of NT protons with ICM

  4. Why study the NT cluster component ? • Non thermal e- creation and acceleration mechanismnot understood! • Diagnostic information on the hierarchical formation process ⇒ probe the physics of merger events (shocks, turbulence, redistribution of energy …) ⇒ probe the ICM magnetic field ⇒ tracer of merger/formation history • Possible impact on cosmological parameters estimate(from N(M) or fgas ) ⇒May contribute to the overall pressure ⇒Mass higher than estimated from the HE equation and Ptherm only Need (new) radio observations combined with X-ray information

  5. Govoni et al, 04 Radio- X-ray comparison for individual clusters (I) Constraints on models density (radio maps) and energy (radio spectra) distribution of NT electrons compared to that of thermal electrons (X-ray) A 520 A 773 Probably mostly acceleration by turbulence Radio versus kT map

  6. -2-1.5-1 Markevitch & Vikhlinin, 01  from 330 MHz/1.4 GHz Feretti et al, 04 Radio- X-ray comparison for individual clusters (II) A665 Strong(er) constraints given by spectral index maps Flattening in region affected by merger ⇒ mergers do supply energy to radio halo No connection to the (weak M ~2)shock⇒re-acceleration by turbulence Extend to much larger cluster samples Radio map (/ Srad) versus X-ray map (ne/kT/P/S) sensitive multi  imagingXMM/Chandra

  7. A2256/Beppo-Sax relic Clarke &Ensslin, 01 halo Fusco-Femiano et al, 00 Global spectrum => ambigous Spatially resolved spectroscopy Radio- NT X-ray comparison for individual clusters SIMBOL-X (~2012) • Radio:degenerate information on B, NT e- • + Faraday Rotation (B, Te-) ⇒ B in few directions • + Hard X-ray : IC (NT e-) ⇒break the degeneracy • e.g. LOFAR + SIMBOL-X(luminous clusters) • LOFAR + XMM?(low mass systems where IC/thermal higher)

  8. Statistical studies (I): correlations with global properties Feretti , 05 and ref therein; Bacchi et al, 03 Giovannini et al, 06 Govoni et al, 01 • Open questions: • Do all clusters with a recent merger have halos/relic? • Do ALL clusters have a radio halo ? • What is the most relevant X-ray quantity and what is the slope/dispersion/evolution of the correlations => quantitative test of models • We need: • X-ray data: exist (XMM/chandra follow-up of ROSAT samples; XMM serendipitous surveys) • Much higher sensitivity radio survey/ follow-up

  9. Chandra Jeltema et al 05 Statistical studies (II): correlations with dynamical state Buote 01 Correlation with departure from relaxation High z clusters are dynamically younger (as expected in hierarchical scenario) The frequency/properties of radio halos is expected to evolve with z … a test of structure formation and merger physics…. also combination with SZ (Planck) data ….

  10. A 1914 LOFAR SKA CONCLUSION • • Detailed combined X-ray/radio spectro imagery ⇒ Physics of hierarchical cluster formation (shocks, turbulence, particles acceleration, B amplification etc…) LOFAR: adapted to steep spectrum well matched spatial resolution SKA: more sensitive higher v capability: aging of e- NB: combining with hard X-ray (e.g. SIMBOL-X) part. interesting.. • Discovery of new relics/halos and statistical properties (correlation with X-ray/SZ) and evolution with z ⇒ again constraints on model PLUS tracer of cluster formation LOFAR (and SKA?): ‘survey’ capability ! Bacchi et al 03 Komissarov & Gubanov 94

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