1. X-shooter II nd Generation VLT Spectrograph for GRBs Paolo Goldoni, SAp/CEA-APC Journee Dourdan - APC 05/12/2003

2. 1967-1997 : The Long Wait BATSE 2704 burst Lack of Weak Bursts w.r.t. uniform distribution in Euclidean space Fluence Φ (cm -2 s -1 ) N (> Φ) Duration distribution bimodal 63% of bursts last < 30 s T 90 (s) Nombre de sursauts 63%

3. Optical Afterglow T B + 6,5 hT B + 12 hT B + 52 h GRB 971214 Afterglow : 1.3-10 keV power law decline 1997 : BEPPO-SAX, the counterparts Host Galaxies Redshift ~ 35 measured redshift (0.16 ~1) Cosmological sources Most energetic (Γ ~100) Emitted energy γ ~ 10 50- 10 52 ergs http://www.mpe.mpg.de/~jcg/grbgen.html

4. Afterglow lightcurves: Breaks, Bumps, Wiggles and the emergency of a SN Wijers et al. 1997 Harrison et al. 1999 Berger et al. 2003

5. GRB 030329: the appearance of SN2003dh Evolution of the GRB 03029/SN 2003 spectrum, from April 1.13 UT (2.64 days after the burst) to April 8.13 UT (9.64 days after the burst). The early spectra consist of a power-law continuum (F ~ ν -0.9 ) with narrow emission lines originating from H II regions in the host galaxy at a redshift of z=0.168 taken after April 5 show the development of broad peaks in the spectra characteristic of a supernova. From Stanek et al. 2003

6. GRB030329: Association with SN Ib for long GRBs From Stanek et al. 2003

7. “Standard” model 1 1Newly Formed BH surrounded by a torus 4Ext. shock 4 3Int. Shock 3 Lorentz Factor > 100 2 2Rel. Ejection 5 5Reverse shock

8. Open problems X-ray Flashes= GRB with lower peak energy Less energetic GRBs ? GRB at High Redshift ? Short Bursts ! No afterglow for T < 1 s Are GRBs an effective SFR tracer ? Structure of the jet ? Beaming ? (At least some) GRBs are the farthest stars we can observe State of the art (Zhang & Meszaros astro-ph/0311321)

9. 1999 : Prompt Optical Emission 123 Discovery of Prompt Optical Emission of GRB 990123 312 Secondes après le déclenchement du sursaut Coups s -1 keV -1 Prompt Emission is not limited to γ-ray domain, GRB 990123 emitted in optical an isotropic equivalent energy of ~ 10 49 ergs (m V ~ 9 in image 2 ) ROTSE-1

10. 2002 : GRB021004 Optical Observations of the error box of GRB 021004 detected and localized with HETE-2 Image NEAT 9 min after the burst m R = 15,3 Image DPOSS (20/8/1990)

11. Name V z 3C 273 ~12.86 0.158 PKS 2155-304 ~13.09 0.17 PG 1634+706 ~14.9 1.33 Brightest Quasars vs. Brightest GRBs Name V z 990123 ~9 1.6 021004 ~15.3 2.3 021211 ~18.2 1.01 Brightest GRBs can be used as new cosmological probes ! IGM study in several line of sights with unprecedented brightness

12. GRBs as cosmological probe Pros 1) Very bright 2) Unperturbed Medium, no proximity effect 3) Isotropic Distribution Cons 1) Very Fast Transient 2) Small Number SWIFT launch ~mid-2004 ~150 localized afterglow/year !

13. Observation strategy at ESO 1) Installation of robotic telescopes at ESO sites: REM, Tarot 2) Development of a dedicated instrument

14. Real Time Counterpart identification, From Space to the Ground Fast Detection with Robotic Telescope (ROTSE, TAROT): Optical/NIR spectroscopy with 8-m class telescope (VLT,Keck…) GRB detection in space, e.g. HETE-2, INTEGRAL, SWIFT: Position within few arcmin Position within ~1” Redshift ~20 % of GRBs with X-ray afterglow do not display optical afterglow: faint, absorption or redshift ? a fast IR robotic telescope is the solution (REM (APC)2001- …)

15. Nas-1 Nas-2 (vide) IR-Camera ROSS REM Telescope (Obs. Milan (I), Dunsink Obs. (Irl.), APC (F)) 60 cm diameter 60 deg in 5 sec 10 x 10 arcmin FOV 1.2 arcsec pixel scale, bright source position <1” 0.9-2.3 micron (Z’,J,H,K) 512X512 HgCdTe Pixel chip @77 Kelvin 10 x 10 arcmin FOV 0.55 pixel scale, bright source position < 1” 0.45-0.9 microns 1024 x 1024 pixel chip Installed in La Silla

16. Project Status The Telescope is in La Silla. Technical tests ongoing. Calibration begin in 2004.

17. “Call for proposals for 2nd Generation VLT Instruments” ( http://www.eso.org/instruments/vlt2ndgenins.html ) The main goal is to get maximum detectivity on stellar or small emission-line objects, while covering the largest possible wavelength range (ideally 0.32 to 2.4  m) in a single observation, presumably leading to a multiple arm ("x-shooter") system. A particularly important requirement is the ability to get spectrographic data on unpredictable/fast varying objects like supernova explosions or gamma ray burst optical counterparts, for the latter if possible in a matter of minutes…. R~ 10 4 wide-band visible-NIR high-throughput Spectrometer Goal of the instrument: Single object observations at the sky limit

18. Consortium NL,D,I,F,ESO Project Constraints and characteristics Very Fast realization ! (SWIFT launch mid-2004). Commisioning in 2006 and operation in 2007 are foreseen More than half budget from member states First second generation instrument to be operative but very tight budget Automatic operations driven by robotic telescopes at Chili: REM (APC) and Tarot-2

19. X-shooter Science Case: Faint Object Spectroscopy

20. GRB Afterglow, host galaxy, line-of-sight absorption 1) Type Ia Supernovae 2) X-ray Binaries Main Scientific Topics for APC The brightest cosmic lighthouses visible up to redshift  15 Stars and Structure formation in The early Universe Secondary Scientific Topics

21. Lamb & Reichart, 2000 X- shooter Spectral range and maximum redshift Wavelength position of absorption lines and Lyman-α forest as a function of redshift. To the right X-shooter spectral range with respect to UVES

22. X-shooter sensitivity Sensitivity to a 30 kms -1 line (moderately strong IGM absorption line) as a function of wavelength: X-shooter, FORS Giraffe and ISAAC

23. Afterglow lightcurve (R~13.6 after 5 minutes, R~18 after 1 day). Arrows mark the ‘cooling’ and ‘injection’ breaks. The vertical line mark the jet break. Afterglow Spectroscopy I : The Time evolution

24. Afterglow Spectroscopy II : The spectral break Afterglow spectra at 4 different epochs along with X-shooter spectral range

25. Cosmological Lyman-α absorption 4 z > 5.8 quasars (Becker et al. 2001). X-shooter wil be able to observe all this band with 1 exposure

26. GRB spectra, where are the lines ? GRB021004 (z=2.23) spectrum taken with NOT R~19.0, importance of a WIDE spectral range

27. X-shooter spectrum of GRB 021004 at z=8.5 Texp = 2 hr, reionization at z=7, 7 hours post burst.

28. Type Ia SNae spectrophotometry Optical/NIR spectrum of SN2002bo (z=0.042) Need great sensitivity + spectral coverage (FORS useful up to z~0.5) IonWavelength (μm) H I0.6563,… He I0.5577,1.0830 C I0.8729,0.9812 O I0.6300,0.6364 Mg I0.4571 Si I1.099,1.645 Si II0.615 Ca II0.7292,0.7325 Fe II0.7155,1.257,1.533

29. Type Ia SNae identification X-shooter ETC simulation, 4h observation, SNIa at maximum z=1.5, I=25.4, J=24.0, H=22.9 (red curve)/template spectrum (black curve), the broad feature is the SiII absorption

30. X-ray Binaires: Rotation Curves and Chemical composition Courbe de vitesse radiale UVES de 2A1822-371 (V~16) Spectre de GROJ1655-40, une metallicite 10 fois celle Solaire est necessaire pour le fitter.

31. Preparation au Retour Scientifique: Developpement d’expertise Spectre NTT/SOFI de IGRJ16318-4848, R~1000 (Chaty & Filliatre en preparation)

32. APC Contribution: Integral Field Unit Fed. APC: GEPI-Meudon, SAp 1.8 x 4 arcsec 2 FOV, 3 spectra separated with three spherical mirrors, no light loss. Hardware GEPI, Analysis Software (DRS) SAp.

33. Why an IFU To perform (mini) area spectroscopy for higher spectrophotometric Accuracy over a wide spectral range of stellar and slightly extended targets To map the spectral characteristics of extended objects To reduce slit losses when operating with narrow spectrograph slits To reach the limiting spectral resolution of the instrument or with bad/variable seeing To reduce the effect of pointing errors when the targets are invisible in the acquisition system (or prompt response considerations preclude the use of the acquisition CCD) and the coordinates are known to +/-1 arcsec accuracy

34. IFU advantage: X-shooter FOV & OT positions Bloom et al. 2001 X-shooter FOV with IFU (1.6” x 3.2”) is superposed to the angular distribution of 20 OTs in their galaxy.

35. http://www-int.stsci.edu/~fruchter/GRB/030329/ GRB 030329 and its host galaxy with HST 12-13 May Observations, V~22.7, M (Galaxy)~-16.5

36. X-Shooter Planning Phase APhase BPhase CPhase D Nov 2003Avr 2004Apr 2005Apr 2006 Apr 2004Apr 2005Apr 2006Jul 2007 6 months12 months 16 months

37. APC Contribution IFU and IFU Data Reduction Software Hardware PI F. Hammer, Software PI: A. Claret Science Team: P. Goldoni, H. Flores, P. Francois, Ph. Filliatre Scientific return: Guaranteed time under discussion ~15 % of total cost Budget: Proposals PNC, PNG, APC

38. Conclusions X-shooter has been approved by ESO STC, it will be the first IInd generation instrument operative at VLT APC/GEPI participation at ~15% guarantees an interesting return It will be the most sensitive VLT single object spectrograph The main scientific aim will be the GRBs with the possibility of detecting the farthest sources at the reionization epoch or beyond ( + SnIa at z > 1 and X -ray Binaries) GRBs = Relativistic Astrophysics AND cosmology