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  = Å (FWHM); MEG  = Å (FWHM) HEG and MEG resolving power (E/  E or  ) as a function of energy for the nominal HETGS configuration

5 Chandra LETGS Resolution LETG  = 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  = 0.06 Å; RGS #2  = 0.07 Å  ~  ~

9 XMM-Newton RGS Effective Area Net effective area of RGS similar to that of Chandra spectrometers, ~100 cm 2, but directed towards longer wavelengths

10 Chandra to XMM-Newton Comparison

11 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 Astro-E2

kg Astro-E2

13 Astro-E2 Instruments

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

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  E = 6 eV E/  E = Fe K 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 Spectral Diagnostic Thresholds

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 10 5 s or less at the faintest flux levels found in the ROSAT deep surveys (2x 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: keV –Minimum effective area: 1,000 cm 2 from 0.25 keV to 10 keV 15,000 cm 2 at 1.25 keV 6,000 cm 2 at 6.0 keV 1,500 cm 2 from 10 keV - 40 keV –Minimum telescope angular resolution: 15" HPD from keV 1' HPD from 10 keV to 40 keV –Spectral resolving power (E/  E): > 300 from 0.25 to 6.0 keV 1500 from 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/  E & 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 m 2 (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 keV imaging and spectra are much less useful, so NeXT will likely have low energy detectors also Goal is microcalorimeter array to cover 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, 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 m 2 effective area, 0.1" angular resolution, spectral resolution E/  E = 10 3 or more Energy range keV Field of view ~ 5' Baseline 4 spacecraft with 25 m 2 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