Overview of Existing and Planned X-ray Spectroscopy Missions

1. Overview of Existing and Planned X-ray Spectroscopy Missions Wilton Sanders Science Mission Directorate Universe Division NASA Headquarters ITAMP Workshop X-ray Diagnostics for Astrophysical Plasmas November 15, 2004

2. Missions • Existing Missions • Chandra X-ray Observatory • XMM-Newton • Planned Missions • Astro-E2 • Constellation-X • Potential Missions • NeXT • DIOS • SMEX/MIDEX (e. g., MBE/HUBE/…) • Gen-X

3. Chandra Spectrometers • Primary spectrometers are the transmission gratings, LETG and METG/HETG, in conjunction with the telescope mirrors and a focal plane detector • For example, the HETGS Capella spectrum, MEG m = -1

4. Chandra HETGS Resolution • HEG Dl = 0.012 Å (FWHM); MEG Dl = 0.023 Å (FWHM) • HEG and MEG resolving power (E/DE or l/Dl) as a function of energy for the nominal HETGS configuration

5. Chandra LETGS Resolution • LETG Dl = 0.05 Å • LETG spectral resolving power, derived from observations of Capella and Procyon with HRC-S detector

6. Chandra HETGS & LETGS Effective Areas • Resolution is not the whole story, effective area (and background) affect sensitivity to lines Solid line - sum of first order spectra from both MEG and HEG

7. XMM-Newton RGS • Compared to Chandra, more mirror area, larger mirror point spread function, broader energy coverage

8. XMM-Newton RGS Resolution • RGS #1 Dl = 0.06 Å; RGS #2 Dl = 0.07 Å • l/Dl ~ 100 - 600 l/Dl ~ 100 - 500

9. XMM-Newton RGS Effective Area • Net effective area of RGS similar to that of Chandra spectrometers, ~100 cm2, but directed towards longer wavelengths

10. Chandra to XMM-Newton Comparison

11. Astro-E2 Developed jointly by the US and Japan (ISAS) - see Cottam poster for more information. • High x-ray spectral resolution throughout energy band where bulk of astrophysically abundant elements exist (O - Ni) • Non-dispersive spectrometers enable imaging spectroscopy of extended sources • Large collecting area for high sensitivity • Very large simultaneous bandwidth to enable disentangling complex, multi-component spectra • Complementary to Chandra and XMM-Newton X-ray Observatories To be launched in 2005

12. Astro-E2 1700 kg

13. Astro-E2 Instruments

14. Sterling Cycle Cooler to extend lifetime to 2.4-3 years Astro-E2 XRS X-ray -calorimeter array

15. 5.5 - 6.5 eV across array (one outlier) Line Spread Function Spectral Redistribution XRS Spectral Resolution & Redistribution

16. XRS Resolution slightly energy dependent

17. Astro-E2 XRS Effective Area

18. Astro-E2 Instruments Effective Area

19. Energy Resolution Comparison

20. Spectral Diagnostic Thresholds E/E = 1000 @ Fe K E = 6 eV diagram from F. Paerels Ignoring Li-like satellites: Ne IX, Mg XI, Si XIII, S XV, Ar XVII, Ca XIX, Fe XXV Including Li-like satellites: Si XIII, S XV, Ar XVII, Ca XIX, Fe XXV

21. Constellation-X • The prime objective of the Constellation-X mission is X-ray spectroscopy • The fundamental mission requirement is to acquire spectra of high statistical quality in an observing time of 105 s or less at the faintest flux levels found in the ROSAT deep surveys (2x10-15 ergs cm-2 s-1 in 0.2 to 2.0 keV) • This implies a factor of 100 increase in throughput over Chandra, XMM-Newton, and Astro-E2, with high spectral resolution, broad band energy coverage • Time frame is ~ 10 year from now

22. Constellation-X Baseline Mission • Baseline mission characteristics: • Band pass: 0.25 - 40 keV • Minimum effective area: • 1,000 cm2 from 0.25 keV to 10 keV • 15,000 cm2 at 1.25 keV • 6,000 cm2 at 6.0 keV • 1,500 cm2 from 10 keV - 40 keV • Minimum telescope angular resolution: • 15" HPD from 0.25 - 10 keV • 1' HPD from 10 keV to 40 keV • Spectral resolving power (E/DE): • > 300 from 0.25 to 6.0 keV • 1500 from 6.0 - 10 keV • Field of view: • SXT > 2.5' diameter, > 30x30 array (5" pixels) • HXT > 8' diameter

23. Constellation-X Schematic Layout Each "science unit" consists of a spectroscopy X-ray telescope (SXT) covering the 0.25 to 10 keV band and a hard X-ray telescope (HXT) covering from 6 to 40 keV. Behind the SXT mirror is a reflection grating array that disperses 50% of the beam to a CCD array. The remainder of the X-rays pass undisturbed to a micro-calorimeter array. For the HXT, X-ray optics are coated with multilayers to enhance their hard X-ray performance, to provide focusing capability in the hard X-ray band.

24. Constellation-X E/DE & Effective Area • The resolving power of the SXT system is shown in the upper panel. The two systems are tuned to provide a minimum resolution of 300 at ~0.8 keV. • The lower panel shows the effective collecting area of the SXT and HXT systems, including the detector efficiency, with the grating and calorimeter curves shown separately. The effective area curves of the spectrometers with R > 300 on Chandra (AXAF), XMM, and Astro-E are also shown.

25. Constellation-X S/C Configurations L2 orbit has the fewest observing constraints, an optimum thermal environment, the lowest radiation environment, and simplified spacecraft communications and operations. The reference configuration consists of four observatories that launch two at a time on a Atlas V class launch vehicle. Each observatory consists of a separate spacecraft bus and telescope module.

26. Constellation-X + XEUS (?) • Exploratory talks have been held between members of the Constellation-X team and those of the European XEUS (X-ray Evolving Universe Spectroscopy) mission about merging the two. • No firm conclusions have been reached, but talks will continue. • XEUS concept is • A 10 m2 (at 1 keV) mirror area • A direct injection to L2 by an Ariane V • High-precision pore optics with 2-5” HED • Separate spacecraft for detector and telescope - requires formation flying

27. NeXT Mission • Pursued by JAXA and US collaborators • Emphasizes Hard X-ray Science (1-80 keV) • Hard X-ray data without 0.3-10 keV imaging and spectra are much less useful, so NeXT will likely have low energy detectors also • Goal is microcalorimeter array to cover 0.3-10 keV with 2 eV resolution (at 6 keV) over 6' field of view with 10-15" angular resolution • May use TES detectors rather than semiconductor (like Astro-E2) • Anticipate getting started in the next couple of years

28. DIOS • DOIS stands for "Diffuse Intergalactic Oxygen Surveyor" • Being pursued as possible future Japanese small mission (SMEX size, < $40M USD) • Array of 2-eV resolution (over soft X-ray band, 0.1-1 keV) TES microcalorimeters behind fast, medium-sized foil-optic telescope (currently four-reflection) • Wide field of view, ~ 0.9° • A dedicated X-ray mission aimed at detection of ~ 30% of the total cosmic baryons via oxygen emission lines • Search for missing "dark baryons" that should now be hot and emitting X-ray lines red-shifted relative to Galactic lines

29. DIOS

30. SMEX/MIDEX Opportunities • Past proposals from Wisconsin/GSFC/JHU/Berkeley/CfA • Future proposals from same groups, plus others …. • Schematic of proposed MBE (Missing Baryon Explorer):

31. Generation-X • Long-range "Vision Mission" • Time frame ~ 20 years from now • Goal of 100 m2 effective area, 0.1" angular resolution, spectral resolution E/DE = 103 or more • Energy range 0.1 - 10 keV • Field of view ~ 5' • Baseline 4 spacecraft with 25 m2 effective area, 50-m focal length, L2 orbit • Study alternative: single 20-m mirror with 125-m focal length and formation flying Science Instrument Spacecraft • Biggest technology driver: telescope mirrors with active control of optics • Note: spectral resolution not much better than today

32. End