1 overview of existing and planned x-ray spectroscopy missions wilton sanders science mission...

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Overview of Existing and Planned X-ray Spectroscopy Missions

Wilton Sanders

Science Mission DirectorateUniverse Division

NASA Headquarters

ITAMP WorkshopX-ray Diagnostics for Astrophysical Plasmas

November 15, 2004

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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

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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

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

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Chandra HETGS Resolution

• HEG = 0.012 Å (FWHM); MEG = 0.023 Å (FWHM)• HEG and MEG resolving power (E/E or ) as a

function of energy for the nominal HETGS configuration





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Chandra LETGS Resolution

• LETG = 0.05 Å• LETG spectral resolving power, derived from observations

of Capella and Procyon with HRC-S detector



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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

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XMM-Newton RGS

• Compared to Chandra, more mirror area, larger mirror point spread function, broader energy coverage

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XMM-Newton RGS Resolution

• RGS #1 = 0.06 Å; RGS #2 = 0.07 Å• ~ 100 - 600 ~ 100 - 500

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XMM-Newton RGS Effective Area

• Net effective area of RGS similar to that of Chandra spectrometers, ~100 cm2, but directed towards longer wavelengths

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Chandra to XMM-Newton Comparison

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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

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1700 kg

Astro-E2

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Astro-E2 Instruments

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X-ray -calorimeter array

Sterling Cycle Cooler to extend lifetime to 2.4-3 years

Astro-E2 XRS

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5.5 - 6.5 eV across array(one outlier)

Line Spread Function

Spectral Redistribution

XRS Spectral Resolution & Redistribution

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XRS Resolution slightly energy dependent

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Astro-E2 XRS Effective Area

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Astro-E2 Instruments Effective Area

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Energy Resolution Comparison

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E = 6 eV

E/E = 1000 @ Fe K

diagram from F. Paerels

Ignoring Li-like satellites: Ne IX, Mg XI, Si XIII, S XV, Ar XVII, Ca XIX, Fe XXVIncluding Li-like satellites: Si XIII, S XV, Ar XVII, Ca XIX, Fe XXV

Spectral Diagnostic Thresholds

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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

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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/E): • > 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

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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.

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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.

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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.

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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

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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

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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

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DIOS



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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):

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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/E = 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

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End

1 overview of existing and planned x-ray spectroscopy missions wilton sanders science mission...

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