instrumentation for x-ray astronomy
DESCRIPTION
A. Goldwurm. CR Workshop – Leiden (H), 14 – 18 / 03 / 2011. 1. Instrumentation for X-Ray Astronomy. A. Goldwurm AstroP articule et Cosmologie Service d’Astrophysique / CEA – Saclay France. Specific Issues of X-ray Astronomy. - PowerPoint PPT PresentationTRANSCRIPT
Instrumentation forX-Ray Astronomy
A. Goldwurm AstroParticule et Cosmologie
Service d’Astrophysique / CEA – Saclay France
A. Goldwurm 1CR Workshop – Leiden (H), 14 – 18 / 03 / 2011
Specific Issues of X-ray Astronomy
1. Earth atmosphere is opaque to X-rays => balloons, rockets or satellites needed
2. Optics: difficult or even impossible to focalize X-rays
3. Detectors of Photoelectric and Compton interactions
4. Sources have intrinsically weak photon fluxes (non-thermal spectra or HE tail of thermal very hot medium)
5. Detectors sensitive to particles and particle-generated X-rays => high level of background => Low S/N ratios
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 satelliteUhuru
• Instruments based on Proportional Counters + collimators
• End of ’70s : focusing telescopes
radio, IR, visible, UVwaves
X and gamma - rays
Jacques Paul Planche 4L’observatoire spatial INTEGRAL – Lycée Arago – Perpignan
Focalisation of Soft X-rays
SoftX - rays
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
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
Nesting W-I Mirrors in a telescope
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.
Major Mirror X-ray Telescopes(untill 2000)
1999
XMM - Newton
XMM Optical System and the Reflection Grating Spectrometer
70 cm
58 mirror shells 0.5 – 1 mm thick
Images from XMM Newton EPIC
• Observations: stabilized pointing of target sources for typical exposures of 5 - 200 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.
Imaging performances of XMM
• 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)
110”
XMM Performances• Effective area of
XMM mirrors plus focal plane instruments
• Typical spectra otained with XMM EPIC
• Calibration +background spectrum with XMM EPIC PN
The Chandra Observatory
And … for E > 10-15 keV ?The concept of a Pinhole camera
source à l’infini
masque codé
détecteur sensibleà la position
The concept of Coded Mask Imaging
source 1
masque codé
détecteur sensibleà la position
source 2
masque codé
détecteur sensibleà la position
The ESA INTEGRAL Mission
Launched with a Proton on 17/10/2002
The First Gamma-Ray OBSERVATORY for the Astronomical Community
A Gamma Ray Observatory
2 main -ray Telescopes
Energy: 15 keV – 8 MeVHigh angular res.: ~ 12’
(IBIS)High spectral Res: DE/E
~=500(SPI)
+ 2 Monitors (opt, X)
SPI γ-ray spectrometer
OMC (visible band)
IBIS γ-ray imager JEM-X (X-ray monitor)
ISGRI camera
IBIS / ISGRI Performances
Energy Band 20 keV-1 MeVAngular Resolution 12’FOV at 100% s. 9° x 9°
at 0 sensitivity 29° x 29°Point Source Location Err. 30” (S/N~30)Temporal resolution 60 s
100 keVSensitivity (ph cm-2 s-1 keV-1) 4 10-7
(for 106 s, 3, E=E) 1 mCrabNarrow line sens. (cm-2 s-1) 10-5 Spectral resolution 8 keV
IBIS: Imager onBoard Integral Satellite
IBIS Data AnalysisDetector Image
Sum of Sky Images
Mask Pattern Reconstructed Sky
MISSSION
LAUNCH
ENERGY OPTICS DETECTORS
FOV AngRes
Areacm2
En.Res(eV)
RXTE 1995 2-60 keV Collimator PropCount 1° 1° 5000 1125(6 keV)
Chandra 1999 0.1 – 10 keV Mirrors CCD 17’ 0.5" 230(6 keV)
170(6 keV)
Newton 1999 0.1 – 10 keV Mirrors CCD 30’ 6" 850(6 keV)
130(6 keV)
INTEGRAL 2002 20 keV - 10 MeV
Cod Mask
CdTe DetGe Det
30° 12’ 2000(1MeV)
SWIFT 2004 1 – 150 keV Mirror Cod Mask
CdTe Det 30’
Suzaku 2005 0.1 – 700 keV
Mirror Collimator
CCDSi Det
20’4.5°
1.5’30’
1000 6 keV
120(6 keV)
MAXI(on ISS)
2008 2 - 30 keV Collimator (ASM)
Gas PCSolid St. C
16 0° x 1.5°
1.5°
Active X-Ray Missions
Same examples of Images obtained with X-ray Focussing Telescopes
and Coded Mask hard X-ray / soft gamma-ray Telescopes
Chandra & XMM Surveys of the GC
6.4 keV Neutral Iron K line
XMM-Newton GC Survey 0.3-9 keV0.0°
0.0°
(Bel
ange
r et a
l. 20
06)
(Dec
ourc
helle
et a
l. 20
03)
0.0° 359.0°1.0°
INTEGRAL GC Survey 20-40 keVSgr A
Sgr B2
INTEGRAL / SPI 511 keV Line
h Spherical shape (Bulge)h 2D Gaussian profile with
FWHM ~ 8ºh Positronium fraction: 0.91
- 0.97h Annihilation in warm ionized
mediumh Origin of positrons unknownh Originated at the GC ?(Knodelseder et al. 2004, Churazov
etal 04, Jean etal 2005, ..)
Centroid: 511.06+0.17/-0.10 keV
Line width: 2.95+0.45/-0.51 keV (FWHM)
Flux:(1.05±0.06)×10-3 ph cm-2 s-1
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.
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 2025In 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