Michael A. Nowak (MIT-CXC) on behalf of Claude Canizares and the Chandra-HETG Group*

1. Recent Highlights from the High Resolution Transmission Grating X-ray Spectrometer on the Chandra X-ray Observatory • Michael A. Nowak (MIT-CXC) • on behalf of • Claude Canizares and the Chandra-HETG Group* (* Anything intelligent that I say, full credit to the group; idiotic statements wholly my own!)

2. The Chandra X-ray Observatory:

3. Chandra History and Specs: • Third of NASA’s “Great Observatories”. Launched July 1999 • High Altitude Orbit (132,000 km); 63.5 hour orbit • Up to 160 ksec viewing windows • Superb Spatial Resolution; 0.5” • ACIS-I (0.8-10 keV), ACIS-S (0.3-10 keV), HRC • Superb Spectral Resolution; E/ΔE = 2300-150 (0.1-6.4 keV) • HETG (HEG, MEG): 3 cm2@23 Å, 40 cm Å; LETG

4. ROSAT Cas A Supernova Remnant Imaging Improvement:

5. 30 ASCA 20 Counts/Bin 10 Protostar, TW Hydrae 2 6 10 14 18 22 26 Wavelength (Å) Wavelength (Å) Spectral Improvement:

6. Chandra HETG: The Most Sensitive 0.9-7 keV Instrument for Line Studies

7. Why We Want High Resolution: • Spectroscopy Tells us the Composition of the Universe • Abundances (see J. Drake’s talk); Phases, e.g., Warm, Hot, Cold, Solid (see J. Lee’s talk) • Spectroscopy is the Best Means to Study the Kinematics of Astrophysical Plasmas • Capella, SS 433, MCG--6-30-15, GRO J1655-40, SN1987A • Line Ratios can yield Temperatures, Densities, & Heating Mechanisms, e.g., Photo- or Collisional Ionization? • M81*, is it Advection Dominated?

8. Stellar Physics: Capella • 42.2 lightyears from Earth, 6th Brightest “Star” in the Sky • Actually, 4 stars, with a Spectroscopic Binary - Capella Aa/Ab • Capella Aa 2.7 Msun, variable, beginning ascent to Red Giant Phase • Capella Ab 2.6 Msun, faster rotating, 104 day orbit • System is used to Study Stellar Physics and Chandra Calibration • Excellent Example of the Accuracy and Power of HETG!

9. MEG -1st Order Stellar Physics: Capella Spectra can be fit with a 3 Temperature Plasma Model

10. Stellar Physics: Capella • Capella Shows 10’s of km/sec velocity residuals • Real Effect! Barycenter & Space-craft Corrections need to be applied! (Ishibashi et al. 2006)

11. Stellar Physics: Capella • Remaining Velocity Shifts Indicate X-ray Dominated by Capella Aa • Orbital Variability Also Seen in Line Fluxes (Ishibashi et al. 2006)

12. Stellar Physics: Capella • Some lines indicate emission from both stars. Mg XII Doublet fitted velocity indicates 2:1 Aa:Ab ratio • Statistics and instrument resolution/stability allow us to carefully model other blends (Ishibashi et al. 2006)

13. MEG 1st MEG 3rd HEG 1st Higher Orders Allow Line Separation: Ne X Lyα Doublet Fe XVII Fe XXIII Ni XX (Huenemoerder et al., in prep.)

14. (Migliari et al., 2002) More Extreme Kinematics - SS 433: • Two sided, relativistic jet with velocity 0.25 c • Orbital period of 13 days • Jet/disk precessing with 162 day period • Baryonic jet, as evidenced by emission (Animation by L. Boroson, MIT)

15. Blue/Redshift Velocities Accurately Measured (Lopez et al. 2006)

16. Recent Observation, Exiting Eclipse, fit with 5 Temperature APED Model

17. Stacking Lines to Perform Detailed Kinematic Modeling Aug. 8 Aug. 12 Aug. 16 Aug. 18 50,000 Velocity (km/s) 0 Time (ks) -30,000 25 ks (Marshall et al., in prep.)

18. The Interstellar Medium: • Just as Quasars + Optical/UV Spectroscopy Probed the Structure of the Intergalactic Medium (IGM), X-ray Spectroscopy + X-ray Binaries Probes the Interstellar Medium (ISM) • Probes the Cold, Warm, and Hot Phases of the ISM • Driving Models of the ISM Distribution • Driving us to Improve Modeling of Edge/Resonance Line Structure • Testing/Calibrating Theoretical Models of Edge & Lines

19. Various Sight Lines Probed

20. The Interstellar Medium: • 4U 1636-53 • Oxygen & Neon Edges Require 20 mÅ Shifts from Theoretical Values • Ne IX is Detection of the Hot Phase of ISM • O/Ne = 5.4 ± 1.6, Fe/Ne = 0.20 ± 0.03, Ne II/Ne I ≈ 0.3, Ne III/Ne I ≈ 0.07 (Juett et al., 2004, 2006)

21. 22 21 20 log(NH sin(b)) 19 18 0.1 1.0 10 100 z (kpc) Model of Disk Distribution: The gas (∼108 Msun) is primarily concentrated around the Galactic disk within several kpc. nH = 5.0 x 10-3 cm-3 exp[-|z|/1.1kpc] Total NH ∼1.6 x1019 cm-2 (Yao & Wang 2005, 2006)

22. Reflection Spectrum: The Active Galactic Nuclei: MCG--6-30-15 • Seyfert 1 Active Galactic Nucleus (AGN), offering an unobscured view of nucleus • Powered by efficient accretion through a “cold”, dense accretion disk • Powerful, compact central source of X-rays ≈100 RG Image: CXO

23. Broad Iron Line: (Young et al., in prep.) Heavily binned 522 ksec Chandra HEG (red) XMM-Newton EPIC-pn (black)

24. (J. Lee et al., in prep.) Galactic O VI O II or FenOm O IV Atomic O I 1s-2p O VII He α O VI O V MCG−6-30-15 O III Inner Shell Resonance Lines: Probing Low Ionization (UV, IR) Processes in the X-rays • MCG-6-30-15 : O I - O VIII (O0+ -O7+), FeI - Fe XXVI (Fe0+ - Fe25+) ! • Potential of tying our X-ray observations to a large body of work in UV, IR ... • Ability to probe sources with high extinction in the X-rays • Kinematic associations between UV and X-ray absorbers • More options for probing the ISM? Both in AGN & our own Galaxy

25. Inner Shell Resonance Lines: Probing Low Ionization (UV, IR) Processes in the X-rays The KLL (1s2s2p) Resonance of Li-like O VI (1s2 2s) O VI in MCG--6-30-15 : NOVI ~ 3 x 1017 cm-2; EW ~ 32 mÅ O VI 2s 1s2 ● Atomic Calculation : Pradhan 2000 ● Discovered in MCG-6-30-15 : J. Lee et al. 2001 O IV O VII He α O VI O V

26. 540 ksec MEG Spectra: Ne IX at High τ (J. Lee et al., in prep.)

27. (Miller et al., 2006) Winds Seen in X-ray Binaries:

28. GRO J1655-40: Binary in Outburst • Typical Blueshifts of 500 km s-1. Modeled as a constant ρ slab, with T=0.2-1 x 106 K, log ξ = 4.2-4.7 • Argued that low velocity, high ionization mean magnetic driving • Note that a fair number of lines remain unidentified (Miller et al., 2006)

29. M81* ULX M81*: Low Luminosity AGN Imaging Allows us to Separate Faint Source from Its Surroundings; Spectra Allows us to Study the Accretion Flow onto the Nucleus

30. M81*: Low Luminosity AGN • Closest extra-Galactic AGN with observable nucleus: 3.6 Mpc • Bolometric luminosity: L ≈ 1041 erg s-1 • HST STIS spectroscopy MBH = 7.0 x 107 Msun • Low-luminosity AGN: L ≈ 10-5 LEdd • Has jet, similar to Sgr A*, but brighter

31. (Young et al., in prep.) Si Kα Si XIV Si XIII Mg XII Ne X Si XIII Portion of the MEG Spectra: • G = (f+i)/r = 0.8 • Hybrid collisionally- and photo-ionized plasma [?]

32. Advection Dominated Accretion Flow? • ADAF outer radius, disk inner radius • Difficult to get strong Fe Kα • Even harder to get strong Si Kα Weak Fluorescence Features Expect Line Emission from Transition Regions & Hot Plasma

33. Close-up of the Fe Region: Fe XXVI • Fe XXVI redshifted by 3000 km s-1 • Fe Kα, Fe XXVI consistent with 2000 km s-1 widths • Si Kα consistent with 600 ± 300 km s-1 widths Fe XXV Fe Kα Fe Kβ? (Young et al., in prep.)

34. Supernova 1987A

35. Existing LETG Spectra (Zhekov et al. 2005)

36. SN1987A: Getting Brighter & Bigger! • MEG -1st Order Simulation Shown • 270 ksec Observation with HETG (Canizares, PI), and 300 ksec with LETG (McCray, PI) • Spatial Information Available, both Via Image and Via Line Widths

37. Summary: • The Imaging Improvement by Chandra is Incredibly Impressive! • Spectral Resolution Improvement is Equally Impressive! • HETG is the Best Instrument for Studying Narrow Absorption & Emission Features in the 0.9-7 keV range • HETG is Used to Study a Wide Array of Astrophysics • Stars, X-ray Binaries, AGN, ISM, Supernovae ... • Data Leading us More Sophisticated Models, with Better Atomic Physics • Data can Help to Calibrate & Test Atomic Physics Models • We are Embarking Upon More Ambitious Observations that Combine Chandra’s Unique Spectroscopy and Imaging