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X-shooter IInd
Generation VLT Spectrograph for GRBs
Paolo Goldoni, SAp/CEA-APC
Journee Dourdan - APC 05/12/2003
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1967-1997 The Long Wait
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1997 BEPPO-SAX, the counterparts
http//www.mpe.mpg.de/jcg/grbgen.html
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Afterglow lightcurves Breaks
, Bumps, Wiggles and the emergency of a SN
Wijers et al. 1997
Harrison et al. 1999
Berger et al. 2003
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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 ? -0.9) with narrow emission
lines originating from H II regions in the host
galaxy at a redshift of z0.168 taken after
April 5 show the development of broad peaks in
the spectra characteristic of a supernova.
From Stanek et al. 2003
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GRB030329 Association with SN Ib
for long GRBs
From Stanek et al. 2003
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Standard model
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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 lt 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 ?
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1999 Prompt Optical Emission
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2002 GRB021004
Optical Observations of the error box of GRB
021004 detected and localized with HETE-2
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Brightest Quasars vs. Brightest GRBs
Name V z 3C 273
12.86 0.158 PKS 2155-304 13.09
0.17 PG 1634706 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
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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 !
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Observation strategy at ESO
1) Installation of robotic telescopes at ESO
sites REM, Tarot
2) Development of a dedicated instrument
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Real Time Counterpart identification, From
Space to the Ground
GRB detection in space, e.g. HETE-2, INTEGRAL,
SWIFT
Position within few arcmin
Fast Detection with Robotic Telescope (ROTSE,
TAROT)
Position within 1
Optical/NIR spectroscopy with 8-m class telescope
(VLT,Keck)
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- )
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REM Telescope (Obs. Milan
(I), Dunsink Obs. (Irl.), APC (F))
60 cm diameter
10 x 10 arcmin FOV 0.55 pixel scale, bright
source position lt 1 0.45-0.9 microns 1024 x 1024
pixel chip
60 deg in 5 sec
10 x 10 arcmin FOV 1.2 arcsec pixel scale, bright
source position lt1 0.9-2.3 micron
(Z,J,H,K) 512X512 HgCdTe Pixel chip _at_77 Kelvin
Installed in La Silla
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Project Status
The Telescope is in La Silla. Technical tests
ongoing. Calibration begin in 2004.
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Call for proposals for 2nd Generation VLT
Instruments (http//www.eso.org/instruments/vlt2n
dgenins.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
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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
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X-shooter Science Case Faint Object Spectroscopy
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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
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X- shooter Spectral range and maximum redshift
Wavelength position of absorption lines and
Lyman-a forest as a function of redshift. To the
right X-shooter spectral range with respect to
UVES
Lamb Reichart, 2000
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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
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Afterglow Spectroscopy I The Time evolution
Afterglow lightcurve (R13.6 after 5 minutes,
R18 after 1 day). Arrows mark the cooling and
injection breaks. The vertical line mark the
jet break.
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Afterglow Spectroscopy II The spectral break
Afterglow spectra at 4 different epochs along
with X-shooter spectral range
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Cosmological Lyman-a absorption
4 z gt 5.8 quasars (Becker et al. 2001).
X-shooter wil be able to observe all this band
with 1 exposure
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GRB spectra, where are the lines ?
GRB021004 (z2.23) spectrum taken with NOT
R19.0, importance of a WIDE spectral range
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X-shooter spectrum of GRB 021004 at z8.5
Texp 2 hr, reionization at z7, 7 hours post
burst.
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Type Ia SNae spectrophotometry
Ion Wavelength (µm)
H I 0.6563,
He I 0.5577,1.0830
C I 0.8729,0.9812
O I 0.6300,0.6364
Mg I 0.4571
Si I 1.099,1.645
Si II 0.615
Ca II 0.7292,0.7325
Fe II 0.7155,1.257,1.533
Optical/NIR spectrum of SN2002bo (z0.042)
Need great sensitivity spectral coverage (FORS
useful up to z0.5)
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Type Ia SNae identification
X-shooter ETC simulation, 4h observation, SNIa at
maximum z1.5, I25.4, J24.0, H22.9 (red
curve)/template spectrum (black curve), the broad
feature is the SiII absorption
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X-ray Binaires Rotation Curves and Chemical
composition
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Preparation au Retour Scientifique
Developpement dexpertise
Spectre NTT/SOFI de IGRJ16318-4848, R1000 (Chaty
Filliatre en preparation)
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APC Contribution Integral Field Unit
Fed. APC GEPI-Meudon, SAp
1.8 x 4 arcsec2 FOV, 3 spectra separated with
three spherical mirrors, no light loss. Hardware
GEPI, Analysis Software (DRS) SAp.
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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
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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.
Bloom et al. 2001
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GRB 030329 and its host galaxy with HST
12-13 May Observations, V22.7, M (Galaxy)-16.5
http//www-int.stsci.edu/fruchter/GRB/030329/
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X-Shooter Planning
Phase A Phase B Phase C Phase D
Nov 2003 Avr 2004 Apr 2005 Apr 2006
Apr 2004 Apr 2005 Apr 2006 Jul 2007
6 months 12 months 12 months 16 months
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APC Contribution
IFU and IFU Data Reduction Software
15 of total cost
Budget Proposals PNC, PNG, APC
Hardware PI F. Hammer, Software PI A. Claret
Science Team P. Goldoni, H. Flores, P. Francois,
Ph. Filliatre
Scientific return Guaranteed time under
discussion
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Conclusions
GRBs Relativistic Astrophysics AND cosmology
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 ( SnIa at z gt
1 and X -ray Binaries)
APC/GEPI participation at 15 guarantees an
interesting return