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

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

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

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

12. Payload –Required Observations –Detectors Detectors We use 3 types of detectors: 1. Wide Field Cameras (WFC) 2.X- Ray Telescope (XPT) 3.Infrared Telescope (IT)

13. Payload –Required Observations –Detectors Wide Field Camera 4 wide field cameras: Size Mask Detector cm 2 90 x 90 70 x 70 Height167 cm Spectral range keV 0.1 - 15 15 - 100 FOV 4 x FOV 30° x 30° 60° x 60° 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. Payload –Required Observations –Detectors X-Ray Pointing Telescope Telescope mirror: Silicon pore optics r = 28 cm, f = 5.5 m Effective Area: 1400 cm 2 @ 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 High spatial resolution + Spectroscopy

15. Payload –Required Observations –Detectors Near Infrared 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. Mission Architecture –Mission Analysis –Spacecraft Engineering –Telemetry –Atitude Control Launcher Soyuz-Fregat Launch: spaceport in Korou Cost: ~ 45M€ Total payload mass: 1500 kg Fairing dimensions: 3.5m in diameter, 7m in height

17. Mission Architecture –Mission Analysis –Spacecraft Engineering –Telemetry –Atitude Control Orbit / Propulsion http://wso.vilspa.esa.es/Conferences/Madrid_2003/Launchers_Russian_capabilities.pdf 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

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 backgroundLarge 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 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 30 bits/photon For 1 WFC: 7600 x 30 = 225 kbits/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. 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 Technical details: Angular speed: 1° in 2 secWhole field of view in only 1 minute! Weight: 4 x 7 kg = 28 kg example of reaction wheel

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

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. 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 Why X-RED? vs. Early Universe Gamma Ray Burst Detection

29. Why X-RED? Early Universe Gamma Ray Burst Detection 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

30. 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 will place constraints on the formation of the first generation of stars and hence on the evolution of the Early Universe.

31. Red Team

32. Science PayloadMission