1. CR Workshop – Leiden (H), 14 – 18 / 03 / 2011
Instrumentation for
X-Ray Astronomy
A. Goldwurm AstroParticule et Cosmologie
Service d’Astrophysique / CEA – Saclay France
A. Goldwurm 1
CR Workshop – Leiden (H), 14 – 18 / 03 / 2011

2. Specific Issues of X-ray Astronomy
Earth atmosphere is opaque to X-rays => balloons, rockets or satellites needed
Optics: difficult or even impossible to focalize X-rays
Detectors of Photoelectric and Compton interactions
Sources have intrinsically weak photon fluxes (non-thermal spectra or HE tail of thermal very hot medium)
Detectors sensitive to particles and particle-generated X-rays => high level of background => Low S/N ratios

3. The early days of X-ray Astronomy
X-ray astronomy starts after the WW II
1962 discovery of the 1st extra-solar X-ray source with Sounding Rocket det
1970 First X-ray satellite
Uhuru
Instruments based on Proportional Counters + collimators
End of ’70s :
focusing telescopes

4. Focalisation of Soft X-rays
X and gamma - rays
radio, IR,
visible, UV
waves
Soft
X - rays
Jacques Paul
Planche 4
L’observatoire spatial INTEGRAL – Lycée Arago – Perpignan

5. X-ray Grazing incidence reflection
Since EX > Eebind then refraction index for X-rays nX < 1 => it exists an incident angle of total external reflection (grazing angle) given by cos θr = nX
For nX = (1-δ), θr = (2δ)½ with δ = N0Zreρλ2/A 2π
(e.g. Giacconi+ 69)
For Heavy Elements Z/A ~ 0.5 and therefore
θr  ρ1/2/ EX
Good reflectors are Au, Ni, Ir, Pt and critical angle are in the range 10’ - 2° for X-rays of 0.1 to 10 keV

6. WOLTER Type I X-ray Mirror System
1 Paraboloid + 1 Hyperboloid polished and coated mirrors
Emax = k f/D keV
for D=1 m diameter & f=10 m focal length => Emax~ 10 keV

7. Nesting W-I Mirrors in a telescope

8. A Focusing X-ray Telescope
Several nested W-I mirrors and coated in Ni, Au or Ir focalize grazing incident X-rays
Into a focal plane position sensitive detector, e.g. a CCD for X-rays
Images are formed with effective area given by nested mirrors and a low background that depends on the detector volume.

9. Major Mirror X-ray Telescopes (untill 2000)
1999

10. XMM - Newton

11. XMM Optical System and the Reflection Grating Spectrometer
70 cm
58 mirror shells
0.5 – 1 mm thick

12. Images from XMM Newton EPIC
Observations: stabilized pointing of target sources for typical exposures of ks
Data are in form of event lists (x, y, t, E)
Analysis: correct, filter, bin and combine event lists into images, spectra, light curves, and then derive source parameters.

13. Imaging performances of XMM
110”
Images of a point source by the 3 EPIC cameras (MOS1 MOS2 and PN)
PSF as function of distance from source:
6" (FWHP), 15" (HEW)

14. XMM Performances
Effective area of XMM mirrors plus focal plane instruments
Typical spectra otained with XMM EPIC
Calibration +background spectrum with XMM EPIC PN

15. The Chandra Observatory

16. The concept of a Pinhole camera
And … for E > keV ?
The concept of a Pinhole camera

17. The concept of Coded Mask Imaging
source à l’infini
masque codé
détecteur sensible
à la position

18. source 1
masque codé
détecteur sensible
à la position

19. source 2
masque codé
détecteur sensible
à la position

20. The ESA INTEGRAL Mission
A Gamma Ray Observatory
2 main -ray Telescopes
Energy: 15 keV – 8 MeV
High angular res.: ~ 12’ (IBIS)
High spectral Res: DE/E ~=500
(SPI)
+ 2 Monitors (opt, X)
Launched with a Proton on 17/10/2002
The First Gamma-Ray OBSERVATORY for the Astronomical Community

21. SPI γ-ray spectrometer
IBIS / ISGRI Performances
Energy Band keV-1 MeV
Angular Resolution 12’
FOV at 100% s. 9° x 9°
at 0 sensitivity ° x 29°
Point Source Location Err ” (S/N~30)
Temporal resolution s
100 keV
Sensitivity (ph cm-2 s-1 keV-1)
(for 106 s, 3, E=E) 1 mCrab
Narrow line sens. (cm-2 s-1) 10-5
Spectral resolution keV
OMC (visible band)
IBIS γ-ray imager
JEM-X (X-ray monitor)
ISGRI camera
SPI γ-ray spectrometer

22. IBIS: Imager onBoard Integral Satellite

23. IBIS Data Analysis Reconstructed Sky Mask Pattern Detector Image
Sum of Sky Images

24. Active X-Ray Missions MISSSION LAUNCH ENERGY OPTICS DETECTORS FOV Ang
Res
Area
cm2
En.Res
(eV)
RXTE
1995
2-60 keV
Collimator
PropCount 1°
5000
1125
(6 keV)
Chandra
1999
0.1 – 10 keV
Mirrors
CCD
17’
0.5"
230
170
Newton
30’
6"
850
130
INTEGRAL
2002
20 keV - 10 MeV
Cod Mask
CdTe Det
Ge Det
30°
12’
2000
(1MeV)
SWIFT
2004
1 – 150 keV
Mirror
Suzaku
2005
0.1 – 700 keV
Si Det
20’
4.5°
1.5’
1000
6 keV
120
MAXI
(on ISS)
2008
keV
Collimator (ASM)
Gas PC
Solid St. C
16 0° x 1.5°
1.5°

25. Same examples of Images obtained with X-ray Focussing Telescopes and Coded Mask hard X-ray / soft gamma-ray Telescopes

26. Chandra & XMM Surveys of the GC
Commenting the talk

27. 6.4 keV Neutral Iron K line

28. XMM-Newton GC Survey 0.3-9 keV INTEGRAL GC Survey Sgr A 20-40 keV
0.0°
XMM-Newton GC Survey
0.3-9 keV
0.0°
(Belanger et al. 2006) (Decourchelle et al. 2003)
INTEGRAL GC Survey
Sgr A
20-40 keV
Sgr B2
0.0°
1.0°
359.0°

29. INTEGRAL / SPI 511 keV Line Spherical shape (Bulge)
2D Gaussian profile with FWHM ~ 8º
Positronium fraction:
Annihilation in warm ionized medium
Origin of positrons unknown
Originated at the GC ?
(Knodelseder et al. 2004, Churazov etal 04, Jean etal 2005, ..)
Centroid:
/-0.10 keV
Line width:
/-0.51 keV (FWHM)
Flux:
(1.05±0.06)×10-3 ph cm-2 s-1

30. Perspectives and Future Missions
Focalization at E > 10 keV, using multilayer coating + long focal L (> 10 m) with extendable mats or formation flying:
Nu-Star (US, 2013) Astro-H (JAXA, +, 2014): Emax ~ 80 keV but Ang.Res > 40’
Several non-selected EU projects: Simbol-X (F-I), COSPIX (M3), NHXM (M3)
Focal-Plane Micro-calorimeters for high spectral res.: Astro-H (and IXO)
Light mirrors (glass layers, silicon pore layers) to obtain large effective areas and sensitivities (IXO)
Small / medium missions: X-ray polarimeters (GEM US 2014) or Large sensitive areas for timing / spectral studies (LOFT)
Coded masks for HE monitoring of transients and GRBs (SVOM Ch – F 2014)
Compton telescopes and Bragg diffusion lenses (M3) for the 1 MeV range.

31. X-Ray Astronomy Programmatics
Chandra, XMM-Newton, INTEGRAL missions extended to 2014
Nu-Star, Astro H, SRG, GEM in development phase
IXO delayed by US Decadal to after 2025
In competition for ESA Cosmic Vision Large class Mission (decision 2011)
No HE mission in the ESA Medium class Missions M1/M2 Missions (Launch 2018)
1 HE mission selected for the ESA M3 call (L 2020): LOFT