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NuSTAR , ITS BACKGROUND AND CLUSTERS OF GALAXIES

NuSTAR , ITS BACKGROUND AND CLUSTERS OF GALAXIES. FABIO GASTALDELLO INAF, IASF-Milano And The Galaxy Clusters NuSTAR Team. The NuSTAR satellite and its focusing capabilities in the hard X-ray band NuSTAR science with galaxy clusters: IC emission and very hot thermal emission

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NuSTAR , ITS BACKGROUND AND CLUSTERS OF GALAXIES

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  1. NuSTAR, ITS BACKGROUND AND CLUSTERS OF GALAXIES FABIO GASTALDELLO INAF, IASF-Milano And The Galaxy Clusters NuSTAR Team

  2. The NuSTAR satellite and its focusing capabilities in the hard X-ray band • NuSTAR science with galaxy clusters: IC emission and very hot thermal emission • The components of the NuSTAR background • First results on galaxy clusters OUTLINE

  3. THE CHALLENGE OF FOCUSING HARD X-RAYS

  4. GRAZING INCIDENCE ANGLE where ρ is density (g/cm3) and E in keV For example even for Pt (ρ=21 g/cm3) at 30 keV is ≈ 0.18 deg, whereas at 5 keV is ≈ 1.1 deg A eff f2 x α2 x R2 Valid for Wolter I optics, where f focal length and R reflectivity (de Korte 1988) THE CHALLENGE OF FOCUSING HARD X-RAYS

  5. Multi-layers: grazing incidence + Bragg reflection N layers of heavy element/ light elements (high/low refractive index as W/Si or Pt/C) with spacing d which is a function of depth (e.g, Christensen et al. 1991) THE CHALLENGE OF FOCUSING HARD X-RAYS

  6. THE NuSTAR SATELLITE HARRISON+13

  7. THE NuSTAR SATELLITE HARRISON+13

  8. CZT detectors with CsI anticoincidence THE NuSTAR SATELLITE HARRISON+13

  9. Intra-cluster medium (ICM) Thermal plasma X-rays (10-30%) Relativistic particles Radio 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

  10. EXTENDED RADIO EMISSION IN CLUSTERS Coma cluster Radio halos fill the volume of the clusters, Mpc extension. Given the short synchrotron lifetime electrons can’t simply diffuse. No detected polarization

  11. EXTENDED RADIO EMISSION IN CLUSTERS A3376 Radio relics linear structures of Mpc size, usually at the outskirts of the diffuse extended emission. 20%-50% detected polarization

  12. CONNECTION WITH CLUSTER MERGERS

  13. CONNECTION WITH CLUSTER MERGERS Radio halo bimodality of clusters: only luminous massive mergers have radio halos (strong support for primary models, i.e. reaccelerated electrons, not electrons produces in p-p collisions, i.e. “secondary models).

  14. CONNECTION WITH CLUSTER MERGERS

  15. IC IN GALAXY CLUSTERS

  16. IC IN GALAXY CLUSTERS

  17. IC IN GALAXY CLUSTERS

  18. VERY HOT GAS IN GALAXY CLUSTERS

  19. Instrumental background due to Compton scattered γ-rays and activation lines (passage trough SAA) • “Aperture” background • Reflection (solar + CXB) • Focused CXB THE COMPONENTS OF THE NuSTAR BKG

  20. CsI Fluorescence INSTRUMENTAL BKG Activation Lines Continuum

  21. APERTURE BKG

  22. APERTURE BKG

  23. REFLECTION BKG

  24. REFLECTION BKG • Dark Earth is not Dark !

  25. REFLECTION BKG Sunshine No sunshine

  26. REFLECTION BKG TI LINE

  27. THE COMPONENTS OF THE NuSTAR BKG

  28. NuSTAR VIEW OF THE BULLET WIK+14

  29. NuSTAR VIEW OF THE BULLET WIK+14

  30. NuSTAR VIEW OF THE BULLET: NO IC DETECTION

  31. 3-10 keV • 10-20 keV COMA CENTER OBSERVATION GASTALDELLO+15

  32. COMA NUSTAR SPECTRAL ANALYSIS

  33. COMA TEMPERATURE MAP GASTALDELLO+15

  34. COMA TEMPERATURE MAP GASTALDELLO+15

  35. COMA THERMODYNAMIC MAPS • “Pressure”=T EM1/2 • “Entropy” = T/EM1/3 GASTALDELLO+15

  36. CONSTRAINTS ON IC • 90% upper limit no more stringent than recent results with non-imaging instruments. Mosaic more useful than central bright pointing

  37. Ratio of fluxes NuSTAR/pn. In black individual points, in red weighted average of sets of 6 region. • A trend with distance from the optical axis is evident GHOST RAYS

  38. Same plot as for NuSTAR/pn but now for NuSTAR/CXO • The same trend is present GHOST RAYS

  39. COMA MOSAIC N.J. Westergaard

  40. COMA MOSAIC Dan WIK

  41. COMA RAY TRACING SIMLATIONS N.J. Westergaard

  42. SOLAR BKG ON COMA 7 • Light curve in the 3-10 keV band

  43. SOLAR BKG ON COMA 7 DETA • Unfiltered • Filtered • No sunshine • Spectral range extended to 2 keV just for plotting

  44. NuSTAR has the capabilities to constrain well hot thermal plasmas (like the 8-9 keV emission in Coma center or 14 keV in the Bullet). Still no luck for IC emission but stringent upper limits. • The established knowledge of the background is ok, effort still needed for a thorough understanding. SUMMARY

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