Bremsstrahlung from CLUSTERS OF GALAXIES

1. Bremsstrahlung fromCLUSTERS OF GALAXIES

2. Clusters of Galaxies:a short overview

3. Clusters of GalaxiesX-ray Band Galaxies Gas DarkMatter 1000x1010 Mo 1014 Mo 1015 Mo

4. X-Ray Imaging X-rays and optical light show us a different picture

5. X-Ray Imaging X-rays and optical light show us a different picture

6. Structure Formation

7. Structure Formation 1000 galaxies within 1Mpc

8. Cluster Gas Density

9. Virial Equilibrium Kinetic Energy for the gas Thermodynamic T-M relation Observables RelationsT-M

10. Status of The IGM Age of Clusters ~ few Gyr; R ~ 1-2 Mpc T ~ 1-10 keV; Gas highly ionized Electrons free mean path Gas may be treated as a fluid Timescale for Coulomb Collisions Electrons are in kinetic equilibrium Maxwellian velocity distribution Timescale for soundwave propagation Gas is in hydrostatic equilibrium

11. Hydrostatic equilibrium (spherical symmetry) We can measure the Cluster mass Dynamical Properties of the Galaxies King profile Beta Profile Isothermal Cluster Intracluster Medium

12. Emission Processes of Clusters of Galaxies in the X-ray Band • The IGM is a Plasma • Electrons are accelerated by the ions • They emit for Bremsstrahlung • Electrons are in kinetic equilibrium (Maxwellian V distr. ) • Cluster emission is mainly thermal Bremsstrahlung

13. Emission Processes of Clusters of Galaxies in the X-ray Band Beside IGM contains some metals (0.3 Solar) They produce line emission

14. X-ray Observations • Gas density • Gas Temperature • Gas chemical composition • If assume hydrostatic equilibrium • Cluster Mass

15. Cooling Flows • Observational evidences • The homogeneous model: one ρ and T at each radius • Observational evidence against homogeneous gas • The inhomogeneous model: Δρ and ΔT at each radius • The role of the magnetic fields in Cooling Flows • Estimates of dM/dt from imaging & spectral data • The fate of the cooling gas

16. Cooling in Clusters LX ngas2 Tg1/2Volume E ngasKTgVolume tcool  E/LXTg1/2 n-1

17. Cooling Flowstcool ≈Tg1/2np-1 • For large radii np is small tcool »tHubble • In the core np is large tcool ~ tHubble The gas within rcool will cool

18. Cooling Flows When the gas cools The pressure becomes lower The gas flows inwards, The density increases in the center The gas cools even faster

19. Observational Evidences for Cooling Flows • X-Ray Imaging • Surface brightness strongly peaked at the center

20. X-ray Observatories • After the rocket experiments during the 1960s, the first X-ray Earth-orbiting explorers were launched in the 1970s: Uhuru, SAS 3, Ariel5 • followed in late 1970s early 1980s by larger missions: HEAO-1, Einstein, EXOSAT, and Ginga.

21. X-ray Observatories • In the 1990s the ROSAT survey detected more than 100,000 X-ray objects • the ASCA mission made the first sensitive measurements of the X-ray spectra from these objects • BEPPOSAX contributed along this line

22. Current X-Ray Missions Chandra XMM-Newton

23. The X-ray Telescope Chandra

24. Chandra detectors

25. PSF

26.  DISPERSIVE SPECTROMETERS • All convert  into dispersion angle and hence into focal plane position in an X-ray imaging detector • BRAGG CRYSTAL SECTROMETERS (EINSTEIN, SPECTRUM X-GAMMA): Resolving power up to 2700 but disadvantages of multiplicity of cristals, low throughput, no spatially resolved spectroscopy • n x  = 2d x sin • TRANSMISSION GRATINGS (EINSTEIN, EXOSAT, CHANDRA) • m x  = p x sin • where m is the order of diffraction and p the grating period • REFLECTION GRATINGS (XMM) • m x  = p (cos - cos) • The resolving power for gratings is given by , assuming a focal lenght f and a position X relative to the optical axis in the focal plane • X = f tan  fsin X = f  so •  is constant

27. Rosat Good Spatial resolution Low or no Spectral resolution ASCA Low Spatial resolution Good Spectral resolution Chandra Versus Previous Generation X-ray Satellites Previous X-ray telescopes had either good spatial resolution or spectral resolution Chandra got both

28. Chandra view of “the Creation” of Michelangelo Rosat view of “the creation” of Michelangelo ASCA view of “the creation” of Michelangelo Chandra Versus Previous Generation X-ray Satellites An Imaginary Test

29. The RGS Result A1795 Tamura et al. (2001a); A1835 Peterson et al. (2001); AS1101 Kaastra et al. (2001); A496 Tamura et al. (2001b); sample of 14 objects Peterson et al. (2003) There is a remarkable lack of emission lines expected from gas cooling below 1-2 keV. The most straightforward interpretation is that gas is cooling down to 2-3 keV but not further. Peterson et al. (2001) Standard CF model predicts gas with T down to at least 0.1 keV!

30. AGN in the central galaxy

31. Radio X Ray Chandra X-ray Observatory Hydra A - X-ray

32. Interaction between radio sources and X-ray gas Chandra Observation of A2052; Blanton et al. 2001 ApJ, 558, L15 Hydra A; McNamara et al 2000; David et al. 2001 Perseus; Fabian et al. 2000 Virgo; Young et al. 2002

33. Chandra Observations of Clusters A 133 Fujita et al. 2002 1E0657 Markevitch et al 2001 A 1795 Fabian et al 2001

34. Chandra OBSERVATION OF 2A0335 P. Mazzotta., A. Edge, Markevitch 2002, submitted

35. The Chandra View Abell 2052 Blanton et al. (2001) Radio lobes fill X-ray cavities Cavities are surrounded by denser & cooler gas

36. The Chandra View Centaurus, Sanders et al. (2001), Taylor et al. (2001) Radio X-ray interaction produces an unusual radio source with small bent lobes

37. The Chandra View Perseus, Fabian et al. (2000) Radio lobes fill X-ray cavities. Inner cavities surrounded by denser & cooler gas. Holes appear to be devoid of ICM, Schmidt et al. (2002) If we assume that the radio lobes are in pressure equilibrium with the surrounding ICM, this is reasonable as no shocks are observed, then it is easy to show that the lobes filled with B field and relativistc particles have a smaller specific weight than surrounding ICM and should therefore detach and rise buoyantly.

38. The Chandra View Abell 2597, McNamara et al. (2001) Expanded viewof the central regionof Abell 2597 after subtracting a smooth backgroundcluster model. The 8.44GHz radio contours are superposed VLA1.4 GHz image ofAbell 2597 at 11’’×6’’ resolution Cavities in Abell 2597are not coincident with bright radio lobes. Instead, they are associated withfaint extended radio emissionseen in a deepVery Large Array radiomap. Ghost cavities are likely buoyantlyrising relics of aradio outburst that occurredbetween 50 and 100Myr ago.

39. Cluster Merger Entropy Density

40. 1E0657 Markevitch et al 2001.