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Galaxy clusters are the most massive (M~10 14 -10 15 M SUN ) objects in the Universe

The astrophysics of galaxy clusters: from X- rays to SZ effect (Part I) Mariachiara Rossetti Milano, 04 /04/ 2012. GALAXY CLUSTERS:WHAT?. Intra-cluster medium (ICM) X-rays (10-30%). Galaxies (5%). Dark Matter Gravitational potential. 1E 0657-156 THE BULLET CLUSTER.

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Galaxy clusters are the most massive (M~10 14 -10 15 M SUN ) objects in the Universe

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  1. The astrophysics of galaxy clusters: from X-rays to SZ effect (Part I)Mariachiara RossettiMilano, 04/04/2012

  2. GALAXY CLUSTERS:WHAT? Intra-cluster medium (ICM) X-rays (10-30%) Galaxies (5%) Dark Matter Gravitational potential 1E 0657-156 THE BULLET CLUSTER Galaxy clusters are the most massive (M~1014-1015 MSUN) objects in the Universe

  3. Rosati et al. (2002) Galaxyclusters: why? Galaxyclustersascosmologicaltools Vikhlinin et al. (2009)

  4. Galaxyclusters: why? • Galaxyclustersasastrophysicalobjects

  5. Galaxyclusters: how? The ICM is the dominantbaryoniccomponentof GC. Hot (107-108 K) and low density (10-2-10-4 cm-3) plasma, ionized H, enrichedwithmetals Thermalbremsstrahlungemission in X-rays Galaxyclusters are extended (˜Mpc) and bright (1043-1045 erg/s) sources in X-rays The Coma Cluster asseenby ROSAT PSPC

  6. Galaxyclusters: how? The ICM is the dominantbaryoniccomponentof GC. Hot (107-108 K) and low density (10-2-10-4 cm-3) plasma, ionized H, enrichedwithmetals SunyaevZel’dovicheffect in mm/submm Galaxyclusters are “extended” (˜Mpc) and prominentsecondaryanisotropiesof the CMB, with a uniquespectralsignature The Coma Cluster asseenbyPlanck

  7. X-rayemissionofgalaxyclusters X-rayspectralanalysisallowsustomeasure the temperature and the density of the ICM. Spatiallyresolvedanalysis: 1D and 2D distributionof the thermodynamicquantitiesof the ICM

  8. b r OSSERVATORE X-ray emission of galaxy clusters X-ray surface brightnessat distance b Isothermal beta model ß=0.67 X-raysurfacebrightnessdropsquickly!

  9. Notation: R marks the radius within which the mass density is  times the critical density c(z) R180=virial radius (m=1) Most of the info from center regions ~0.25 r180 r180 = 12.3’  2.5 Mpc Abell 963 z = 0.206 kT = 7.4 keV r180 rmax • rmax = 6’ •  1.2 Mpc • 50% r180 • ≈R500 Abell 963 EPIC XMM-Newton 0.4-2.0 keV

  10. Outer regions sou  bkg OUTER REGIONS Inner regions sou >> bkg

  11. Background + Source model (XMM-Newton) NXB=instrumental background (particles + fluorescentlines ) QSP=variableinstrumentalcomponent (solar soft protons) CXB=CosmicX-ray background (unresolvedpointsources) Halo =galacticforegroundemission X-raymeasurements in clustersoutskirtsrequire a detailed background modeling and a careful treatment ofsystematics (Leccardi & Molendi, 2008)

  12. Existing and future(?) X-rayobservatories are notsuitedforstudyingextendedfaintemission. Requirements: Low equatorialorbitto reduce particle background and goodangularresolutiontoresolve CXB. Possiblydedicatedobservationalstrategy

  13. The Sunyaev-Zel’dovich (SZ) effect Distorsion in the CMB spectrum due to Inverse Compton scatteringof CMB photonswithelectronsof the ICM • Thermal SZ • Kinetic SZ • Relativistic SZ

  14. The Sunyaev-Zel’dovich (SZ) effect The thermal SZ has a uniquespectralsignature (independent on the cluster properties)

  15. The Sunyaev-Zel’dovich (SZ) effect The thermal SZ has a uniquespectralsignature (independent on the cluster properties) ICM thermalpressure

  16. The Sunyaev-Zel’dovich (SZ) effect • The integrated SZ signalisproportionalto the total mass (cosmology!) • The spectraldistortioncaused by SZ isredshiftindependent (an efficient way to find clusters)

  17. The SZ effect with Planck • Unique band coverage (on bothsidesof the spectrum ) • Allskysurvey (allows detection of the rarestobjects) • Moderate spatialresolution • 5 Earlypapers (earlycatalogue and properties) • 2 published Intermediate papers (validation and high z massive cluster) • 7 Intermediate papers on astrophysicsofgalaxyclusters(stay tuned) • Cosmologypapers and finalcatalogue

  18. The SZ effect with Planck A2256 (S/N = 28) Rawmaps Planck Collaboration 2011 • Typical SZ sources are barelyvisible in rawfrequencymaps: needadaptedtechnique to find clusters. • Matched Multi FilterAlgorithm MMF3 (Melin et al 2006) • enhances SZ signal over othercomponents: • knownspectralsignature • knownspatialshape Universal pressure profile: predicted dark matterdistribution from simulations (Navarro,Frenk & White 95, Nagai et al 07) Parametersestimated from a X-ray sample (Arnaud et al 2010) Thisis for blind SZ detection (YSZ), for known cluster (or with follow-up X-rayobservations) we can estimate the SZ signalusing X-raypriors, e.g. position, size (Y500)

  19. The SZ effect with Planck A2256 (S/N = 28) Raw and CLEAN maps Planck Collaboration 2011 Use component separationtechnique to clean the maps. Severalmethodsbased on Internal Linear Combination (MILCA, Hurier et al 2010): removal of thermaldust, radio and IR sources, and of the CMB. Reconstruction of SZ y-maps: 2D distribution of the SZ signal and of the thermodynamic properties of the ICM As with X-rays? Yes, butaftersmoothing with a 10 arcminbeam

  20. SZ effect vs X-rays? r180 rmax Planckallows to map the ICM up to the virialradius and beyond! At least for nearby massive objects “Where no man hasgonebefore” (P. Mazzotta, Planck Conference 2012) Clusters outskirts

  21. The Coma Cluster ROSAT PSPC MOSAIC The Coma Cluster is the closest (z=0.022) massive hot (kT=8 keV) cluster: ideal for SZ studies Itisspatiallyresolved by Planck (10 arcmin=260 kpc) PLANCK Y-MAP 5 degrees ButPlanck can alsoseefinerdetails on Coma (P.Mazzotta, Planck Conference 2012) “Shocking News” comingsoon!

  22. SZ effect vs X-rays? Cluster Cosmology: need an unbiased way to find clusters and measuretheirmasses Planck Collaboration (2011): Planck Collaboration (2011): Discovery of a massive luminous cluster at z≈1 BUT relies on follow-up observation for measuringredshift and size

  23. SZ effect vs X-rays? Cluster Cosmology: need an unbiased way to find clusters and measuretheirmasses Planck Collaboration (2011): Goodlow-scattercorrelationbetweenintegrated SZ signal and total mass BUT relies on follow-up observation for measuringredshift and size

  24. SZ effect vs X-rays? SZ effect can be measuredalso from earth. Alreadymanyexistinginstruments: SPT, ACT, APEX SZ, Bolocam, AMI, Mustang… Technology quicklyimproving: SPTpol, ACTpol, CCAT… Veryactivefield!

  25. SZ effect vs X-rays? X-rayastronomyisaccessible and “easy” (first approximation): public data after 1 yrproprietaryperiod, public data analysis software, standard procedures SZ observations are not: proprietary data and software. Youhave to be in collaborations. SZ effect with X-rays! X-rays and SZ are complementary. 6 PIP on galaxy clusters are obtainedcombining X-rays and SZ

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