Early Universe Gamma Ray Burst Detection

1. Early Universe Gamma Ray Burst Detection 2004

2. Scientific Rationale • The first generation of stars were very important for the conditions of the early Universe! • Synthesis of heavy elements • Reionization of the Universe • In order to understand the Universe at this time, we have to understand the first generation of stars

3. Gamma Ray Bursts GRBs are the brightest objects known in the Universe. Detectable to redshifts of 20 or even more!

4. Gamma Ray Bursts GRBs are the brightest objects known in the Universe. Detectable to redshifts of 20 or even more! Gamma Ray Bursts are unique probes of the death of these first stars !

5. Current Understanding GRBs are emitted in the collapse of massive and fast spinning stars (hypernovae) We expect the first stars to generate GRBs through a similar mechanism

6. Mission Objectives Primary objective Detection of extremely high redshift Gamma Ray Bursts (GRBs) as a probe of the first generation of stars. Secondary objectives ○ Properties of the intergalactic matter ○ X-ray flashes of proto-stars ○ Studies of extragalactic objects

7. Mission Objectives Demands for primary objective • Wide Field Camera (position) • X-Ray (position, spectroscopy) • Infrared (spectroscopy)

8. Mission Design Overview • Payload • Required Observations • Detectors • Wide Field Camera • Pointing X-Ray Telescope • Near Infrared Telescope • Mission Architecture • Mission Analysis • Spacecraft Engineering • Telemetry • Attitude Control

9. Payload • Required Observations • Detectors Known GRBs Prompt emission: 0.1 –100 s with energy peak ~ 150 keV • Afterglow emission in X-ray and optical

10. Lamb & Reichart 2000 • Payload • Required Observations • Detectors High-z GRBs • Peak emission shifted to X-ray energies • UV lines shifted into the infrared (specifically Ly alpha) • Time dilatation

11. Payload • Required Observations • Detectors High-z GRBs Prompt emission fluxes z = 10 z = 20 z = 30 • 0 0.5 1 • Number of photons / cm2 / s • 1-2 2-4 4-6 6-8 (keV) • Energy bin

12. Detectors • Payload • Required Observations • Detectors • We use 3 types of detectors: • Wide Field Cameras (WFC) • X- Ray Telescope (XPT) • Infrared Telescope (IT)

13. Wide Field Camera • 4 wide field cameras: • Payload • Required Observations • Detectors Coded Mask Imaging device Size: 90 x 90 cm2 Material: Tungsten IBIS mask DEPFET type: Soft X-Ray detector CdTe type: Hard X-Ray detector

14. X-Ray Pointing Telescope High spatial resolution + Spectroscopy • Payload • Required Observations • Detectors • Telescope mirror: • Silicon pore optics • r = 28 cm, f = 5.5 m • Effective Area: 1400 cm2 @ 1.5 keV • FOV: 10 arcmin • Angular resolution: 5 arcsec ( 2 arcsec) • Detector: • DEPFET • Size: 3.2 x 3.2 cm2 [640 x 640 pixels] • no active cooling Pore structure optics

15. Near Infrared • Payload • Required Observations • Detectors • NIR Telescope: • Diameter: 0.85 m • Weight: 50 kg • Height: 1.5 m • NIR Camera: • FOV: 10 x 10 arcmin • Sensitivity for R ~ 100: • 26.8 mJy@10σ • Angular Resolution: ~0.3 arcsec • Rockwell Scientific HgCdTe 2048 x 2048 pixels • Passive cooling Ritchey-Chrétien design

16. Launcher • Mission Architecture • Mission Analysis • Spacecraft Engineering • Telemetry • Atitude Control Soyuz-Fregat Launch: spaceport in Korou Cost: ~ 45M€ Total payload mass: 1500 kg Fairing dimensions: 3.5m in diameter, 7m in height

17. Orbit / Propulsion • Mission Architecture • Mission Analysis • Spacecraft Engineering • Telemetry • Atitude Control • Orbit: • halo-orbit around L2 • excluding observational on the galactical • plane. • Propulsion System: • Correct the flight trajectory to L2 • Keeping around the L2 • Offloading of the reaction-wheels • Propellant: hydrazine http://wso.vilspa.esa.es/Conferences/Madrid_2003/Launchers_Russian_capabilities.pdf

18. Mission Architecture • Mission Analysis • Spacecraft Engineering • Telemetry • Atitude Control Accomodation

19. Mission Architecture • Mission Analysis • Spacecraft Engineering • Telemetry • Atitude Control Accomodation 3D Plot and Rotation

20. Mission Architecture • Mission Analysis • Spacecraft Engineering • Telemetry • Atitude Control Mass estimates Payload mass: 550 kg Spacecraft bus dry mass: 776 kg Propellant mass: 50 kg Total mass: 1376 kg Low mass spacecraft Smaller launcher Cheaper mission Very exciting science for very low cost!

21. Mission Architecture • Mission Analysis • Spacecraft Engineering • Telemetry • Atitude Control Power • Solar Arrays: Highly efficient Multijunction GaInP/GaAs • Efficiency: 19 % • Area: 12 m² • Power (avg.): 700 W • Battery for peak power and backup

22. Mission Architecture • Mission Analysis • Spacecraft Engineering • Telemetry • Atitude Control Thermal Control • Instruments Temperature: • IR: ~50K • Hard X: ~253K

23. Mission Architecture • Mission Analysis • Spacecraft Engineering • Telemetry • Attitude Control Telemetry: Overall Data Rate • Diffuse X- Ray background Large amount of data from the WFC Detailed calculations for 1 WFC: Expected number of counts: 7600 photon/s Data / photon: X-Ray energy + (x,y) position 30 bits/photon For 1 WFC: 7600 x 30 = 225 kbits/s 4 WFC: 900 kbits/s X-Ray telescope: 100 kbits/s IR telescope: 2 kbits/s Housekeeping: 2kbits/s Total data rate: 1 Mbit/s • Including all • the instruments:

24. Mission Architecture • Mission Analysis • Spacecraft Engineering • Telemetry • Attitude Control Telemetry: Communication • Continuous data transmission through a high gain antenna • Quasi real time ground data processing [15 s delay] • Medium gain antenna for minor transmissions or emergency situation • On board data storage: few Gbits • Realistic scenario in 10 years [assuming improvements in antenna technology]

25. Technical details: • Angular speed: 1° in 2 sec Whole field of view in only 1 minute! • Weight: 4 x 7 kg = 28 kg • Mission Architecture • Mission Analysis • Spacecraft Engineering • Telemetry • Attitude Control Attitude Control • 4 reaction wheels: • 3 orthogonal [necessary for 3D pointing] • 1 in a plane tilted with an angle of 45° to the • other ones [as a fail safe] • but... why reaction wheels? • Monopropellant trusters require extra fuel and are less accurate in pointing • Control of the angular position and rotation example of reaction wheel

26. Observational Strategy position ~ 5" spectrum WFC every 1ms position ~ 1" spectrum ~ 60 s XPT pointing evtl. repointing spectrum IR ~ 100s Ground station Earth telescopes follow-up observations e.g. VLT, ...

27. Estimated Costs Payload: 15 MEuro Spacecraft bus: 41 MEuro Program level: 7 MEuro Ground Equipment: 5 MEuro Launch: 45 MEuro Total estimated cost (without operation costs): ~ 113 Meuro • 3 years Mission (possible extension) • Spacecraft designed for 10 years lifetime

28. Why X-RED? • Areas where X-RED is improving on SWIFT: • X-Ray sensitivity below 10 keV – important for high z detections • Same area, same sky coverage, but lower background • IR telescope for follow-up observation • Continous observations from L2 vs. Early Universe Gamma Ray Burst Detection

29. Why X-RED? • Areas where X-RED is improving on SWIFT: • X-Ray sensitivity below 10 keV – important for high z detections • Same area, same sky coverage, but lower background • IR telescope for follow-up observation • Continous observations from L2 Early Universe Gamma Ray Burst Detection

30. will place constraints on the formation of the first generation of stars and hence on the evolution of the Early Universe. Conclusions • High redshift GRBs (z = 10-30) are detectable with • IR-Spectroscopy allows to measure the redshift of these GRBs • In a 3 year mission we estimate to detect 10 GRBs with z>10

31. Red Team

32. Science Payload Mission