instrumentation for x-ray astronomy

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