1. IRAC 8 micro K-band 0.5-2 keV X-ray Emission Line Spectroscopy of Diffuse Hot Plasma XMM-Newton RGS Liu, Wang, Li, & Peterson 2010 Li & Wan 2007 T ~ 3 x 10 6 K Lx~2x10 38 erg/s Chandra ACIS-I

2. X-ray spectroscopy: He-like ions R ( or W) : Resonance line (allowed) 1s2p 1 P 1  1s 2 1 S 0 electronic dipole transition I (or x+y): Intercombination line 1s2p 3 P 1  1s 2 1 S 0 (y) 1s2p 3 P 2  1s 2 1 S 0 (x) Triple or quadruplet F (or z): Forbidden line 1s2s 3 S 1  1s 2 1 S 0 relativistic magnetic dipole transition (A ji very low) Simplified Grotrian diagram Porquet & Dubau (2000) R I F Photo-ionized plasma as seen in an AGN can have stronger forbidden lines.

3. Solar Wind Charge Exchange From Dennerl 2010

4. Solar Wind Charge Exchange Charge exchange (CX) nature of comet X-ray emission is confirmed, spectroscopically and temporally. CX has a cross-section of ~10 -15 cm -2 P CX /P th propto 1/n e 2 on scales of mean free path Peter Beiersdorfer CX is also expected at the heliosphere

5. Much of the diffuse soft X-ray background may arise from the CX! ROSAT all-sky survey in the ¾-keV band X-ray binary AGN Futamoto et al. 2004, Wang et al. 05, Yao & Wang 05/06, Yao et al. 06/07/08 4U1957+11

6. X-ray absorption line spectroscopy of diffuse hot plasma Fe XVII K  Tracing all K transitions of metals  all three phases of the ISM. Not affected by photo- electric absorption  unbiased measurements of the global ISM. Yao & Wang 2006, Yao et al. 2006, Futamoto et al 2004 LETG+HETG spectrum of LMXB 1820-303

7. Chandra ACIS observations of nearby galaxies Soria & Wu (2002) (Credit: NASA/CXC/SAO/R.DiStefano et al.)

8. XMM-Newton RGS spectrum of the nuclear starburst region of M51 Charge exchange may be responsible for much of diffuse soft X-ray emission in both normal and starburst galaxies.

9. Similar CX signatures are also observed in starburst galaxies Soft X-ray arises primarily from the interplay between a superwind and entrained cool gas clouds. Composite of optical (HST), infrared (Spitzer), and X-ray (Chandra) images Li, Mao, Wang 2011

10. XMM-Newton Reflection Grating Spectrometers

11. Spatially-resolved X-ray spectroscopy OVIII contours on HST image OVIII contours on OVII image

12. NGC 4438 in the Virgo Cluster Ha+[NII] image (Kenney et al. 1995).Chandra 0.3-2 keV image, Machacek et al. 2004

14. Operating X-ray Telescopes SWIFT Chandra Suzaku XMM-Newton

15. Future X-ray telescopes Astro-H, planned for launch in 2013 eROSITA 2012 Athena???

16. Summary X-ray spectroscopy is the future of the X- ray astronomy  X-ray astrophysics, providing key diagnostics of plasma in the Universe. Much of the diffuse X-ray emission from galaxies may arise from the charge exchange. A lot can already be done to understand the process, which traces the galactic feedback and the presence of cool gas, especially in low density environments.