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X-shooter II nd Generation VLT Spectrograph for GRBs

X-shooter II nd Generation VLT Spectrograph for GRBs. Paolo Goldoni, SAp/CEA-APC. Conseil Scientifique - APC 21/11/2003. 63%. Nombre de sursauts. N (> Φ). T 90 (s). Fluence Φ (cm -2 s -1 ). Lack of Weak Bursts w.r.t. uniform distribution in Euclidean space.

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X-shooter II nd Generation VLT Spectrograph for GRBs

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  1. X-shooter IInd Generation VLT Spectrograph for GRBs Paolo Goldoni, SAp/CEA-APC Conseil Scientifique - APC 21/11/2003

  2. 63% Nombre de sursauts N (> Φ) T90 (s) Fluence Φ (cm-2 s-1) Lack of Weak Bursts w.r.t. uniform distribution in Euclidean space Duration distributionbimodal 63% ofbursts last < 30 s BATSE 2704 burst 1967-1997 : The Long Wait

  3. GRB 971214 Afterglow : 1.3-10 keV power law decline TB+ 6,5 h TB + 12 h TB + 52 h Optical Afterglow Host Galaxies Redshift ~35 measured redshift (0.16 <z < 4,5, <z>~1) Cosmological sources Most energetic (Γ ~100) Emitted energy γ ~ 1050-1052 ergs 1997 : BEPPO-SAX, the counterparts 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 Evolutionof the GRB 03029/SN2003 spectrum, from April1.13 UT (2.64 daysafter the burst) toApril 8.13 UT (9.64days after the burst).The early spectra consistof a power-law continuum (F~ ν-0.9) withnarrow emission lines originatingfrom HII regionsin the host galaxyat a redshift ofz=0.168 taken after April 5show the development ofbroad peaks in thespectra characteristic of asupernova. From Stanek et al. 2003

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

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

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

  9. Discovery of Prompt Optical Emission of GRB 990123 1 2 3 Coups s-1 keV-1 1 2 3 Secondes après le déclenchement du sursaut Prompt Emission is not limited to γ-ray domain, GRB 990123 emitted in optical an isotropic equivalent energy of ~ 1049 ergs (mV ~ 9 in image 2 ) ROTSE-1 1999 : Prompt Optical Emission

  10. mR = 15,3 Image NEAT 9 min aftertheburst Image DPOSS (20/8/1990) 2002 : GRB021004 Optical Observations of the error box of GRB 021004 detectedand localizedwith HETE-2

  11. Brightest Quasars vs. Brightest GRBs Name V z 3C 273 ~12.86 0.158 PKS 2155-304 ~13.09 0.17 PG 1634+706 ~14.9 1.33 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. “Call for proposals for 2nd Generation VLT Instruments” (http://www.eso.org/instruments/vlt2ndgenins.html) R~ 104 wide-band visible-NIR high-throughput Spectrometer 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 mm) 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…. Goal of the instrument: Single object observations at the sky limit

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

  15. X-shooter Science Case: Faint Object Spectroscopy

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

  17. 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 Lamb & Reichart, 2000

  18. 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

  19. Afterglow Spectroscopy I : The Time evolution 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.

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

  21. 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

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

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

  24. APC Contribution: Integral Field Unit Fed. APC: GEPI-Meudon, SAp 1 spectrum for every micro lens: PSF sampling and ~ 1 magnitude gain w.r.t. slit spectrograph Realised by GEPI-Observatoire de Paris (Girafe): DRS responsibility of SAp

  25. 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

  26. IFU advantage: X-shooter FOV & OT positions X-shooter FOV with IFU (1.6” x 3.2”) is superposed to the angular distribution of 20 OTs in their galaxy. 1 pixel is 0.2” x 0.2”. Bloom et al. 2001

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

  28. X-Shooter Planning

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

  30. Conclusions X-shooter has been approved by ESO STC, it will be the first IInd generation instrument operative at VLT 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 APC/GEPI participation at ~15% guarantees an interesting return

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