1. Atomic Physics Explains the Universe Randall Smith Smithsonian Astrophysical Observatory

2. Building Structure

3. Relaxing Structure Fabian et al., Nature, 1984 Most of the mass is in-between the clusters, with kT ~ 1-10 keV. Hydrostatic equilibrium plus radiative cooling implies that at some point the temperature at the core must collapse (to ~10 4 K, whereupon the gas forms stars). This is inevitable unless the gas is heated. However, “No stable heating process yet devised is able to counteract the effects of radiative cooling and account for the observed X-ray images and spectra.” (Fabian, ARA&A, 1994)

4. Spectra from Real Structure Peterson et al. 2003: Cluster cooling flows don’t cool. 36 ksec 20 ksec 40 ksec 38 ksec 26 ksec 54 ksec 29 ksec 39 ksec 33 ksec 36 ksec 50 ksec

5. Heating Structure

6. Turbulent Structure? Doesn’t seem like it – in some cases, line width limits show that the turbulent support for clusters is < 13% of that needed (Sanders et al. 2010). So any heat input is relatively ‘gentle.’

7. Lesson: We Need a Diagnostic for the Heat Source Any heat source will leave a spectral imprint on the gas – a doppler shift, line broadening, ion balance. High resolution spectra combined with accurate plasma models are absolutely necessary if we are to find this source.

8. Enriching Structure? After de Plaa et al 2007 We cannot match the observed abundances in clusters to any linear combination of the two sources. Possibly due to inadequate atomic models? Argon line data from mid-80’s (but so is Sulfur and Calcium data)…

9. Lesson: All X-ray Bright Lines are Important AtomDB update (thanks to Adam!) – All H-like, He-like collisional data now ‘modern’ – DR, RR level-separated rates updated for H-like, He-like, Li-like and Fe L-shell ions – Ionization/recombination rates from Bryans et al. compilation – CHIANTI v6.0 used for non-X-ray emitting ions

10. New Instruments/Missions Astro-H: Planned launch in 2014 with 32 pixel silicon microcalorimeter

11. Astro-H Effective Area & Resolving Power

12. Sample Science: A2029 Using redshifted Fe XXV lines, measure the amount of turbulence in the cluster – something currently only possible with a particular type of cluster.

13. Expelling Elements in M82

14. High Spectral Resolution, High Cadence, Imaging X-ray Microcalorimeter Arrays for Solar Physics Simon Bandler, Catherine Bailey, Jay Chervenak, Megan Eckart, Fred Finkbeiner, Caroline Kilbourne, Daniel Kelly, Richard Kelley, F. Scott Porter, Jack Sadleir, Stephen Smith - X-ray Astrophysics Laboratory at GSFC Jay Bookbinder, Ed DeLuca, Randall Smith - SAO Supported by NASA ROSES: Solar & Heliospheric Physics Original motivation: RAM - Microcalorimeters to study dynamics & energetics of solar corona Simultaneous imaging, spectroscopy & high cadence Pixels need to be small and fast

15. How small are the pixels ? 42  m 9.1  m

16. What energy resolution is achievable ? Mn K  1 & K  2 x-rays at 6 keV from an 55 Fe internal conversion source Instrumental broadening consistent with a gaussian response with 2.13 eV resolution FWHM

17. Solar X-Ray Spectroscopy Excellent selection of lines with formation temperatures between 2-30MK. Density sensitive lines covering temperatures from 2- 10MK. Strong lines from Fe, O, N, Na, Ne, Ni, Ca, Cr, Ar, Mg, Si, S Strong iron emission lines, Fe XVII – XXIV Continuum emission between 1.5-10A Detection of non-thermal electrons from small flares Modeling of X-ray Spectra is well developed and allow scientists to compare detailed forward models with state-of-the-art observations.

18. Hot component has 1% EM of AR component

20. The Decadal recognized "IXO’s high scientific importance" as a "powerful X-ray telescope that will transform our understanding of hot gas associated with stars and galaxies in all evolutionary stages" and also states that IXO is "central to many of the science questions identified by this survey." The report summarizes that NASA should "determine an appropriate path forward to realize IXO as soon as possible" if IXO is selected by ESA as an L-class mission, and that IXO has been recommended for approximately $200M in technology development funding for this decade. IXO: From The Decadal to Cosmic Visions