EELT and Gammaray bursts

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E-ELT and Gamma-ray bursts Frédéric
Daigne(Institut dAstrophysique de
Paris) Réunion E-ELT du Programme
National de Cosmologie, IAP, 31 mai 2007.
1. GRBs2. GRBs and cosmology3. E-ELT and GRBs
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1. GRBs
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GRB prompt emission
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Duration
Spectrum
10 s
100 ms
keV ? MeV
Lightcurves
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(No Transcript)
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GRB 970228
GRB afterglows? temporal decay hours,
days? spectral evolution X,V,radio
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GRB 970508
Host galaxy z 0.835
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GRB 050904 z 6.29 !
TAROT detection _at_ 86 s I 16 (Quasar z 6.37,
I23.3)
Timescales are multiplied by 1z 7.3 (T90gt200 s)
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SWIFT redshift distribution of long GRBs
(Jakobsson et al.)
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Optical afterglows compilation by Zeh, Kann and
Klose
1 h
pre-SWIFT era
R 15-20
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Optical afterglows compilation by Zeh, Kann and
Klose
1 h
pre-SWIFT era
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Optical afterglows compilation by Zeh, Kann and
Klose
short GRBs
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Optical afterglows compilation by Zeh, Kann and
Klose
pre-SWIFT eraGRBs _at_ z1
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Optical afterglows compilation by Zeh, Kann and
Klose
short GRBs
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Long GRBs are associated with massive stars
GRB 980425 / SN 1998bwz0.008
GRB 030329 / SN 2003dhrz0.168
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Short GRBs NS-NS mergers ?
Weak optical afterglowsHost elliptical
4 irregular 1 starforming 1
z 0.266
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GRBs models
Energetics 1051 1054 erg (isotropic) 1051
erg (after correction for beaming)Redshift
0.008 ? 6.3
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Initial event Collapsar (long GRBs)Mergers
(short GRBs ?) ? Stellar black hole thick disc
R in meters
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R in meters
Transparency
Coasting phase Final Lorentz factor G ? 100 !
Relativistic ejection
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? Internal shocks ? Prompt g/X-rays / optical
?
R in meters
Transparency
Coasting phase
Relativistic ejection
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? Reverse shock ? Optical flash ?
Internal shocks
R in meters
Transparency
Coasting phase
Relativistic ejection
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? Forward shock ? Afterglow
Contact discontinuity
Reverse shock
Internal shocks
R in meters
Transparency
Coasting phase
Relativistic ejection
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? Lateral expansion Starts at late time.
Forward shock
Discontinuité de contact
Reverse shock
Internal shocks
R in meters
Transparency
Coasting phase
Relativistic ejection
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2. GRBs and cosmology
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Host galaxy - source environment -
ISM Intergalactic medium
GRB 050730 z3.969 (Chen et al. 05)R17.7 4
hours after the burstISM N(HI)22.15 Z/Z?1/1
00IGM DLA _at_ z3.564 LLS _at_ 3.022 MgII abs. _at_
z2.253,1.773
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GRB 050904 _at_ z 6.3
Kawai et al. 2005 (Subaru)
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Host galaxy - source environment -
ISM Intergalactic medium ? Chemical evolution
(structures, IGM) ? QSOs vs GRBs some
differences (z distribution, initial luminosity,
angular size, impact on environment, )
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Host galaxy - source environment -
ISM Intergalactic medium ? Chemical evolution
(structures, IGM) ? QSOs vs GRBs some
differences Needs accurate spectroscopy at
early times, when the afterglow is still bright
(first hour after the burst).? GRB hosts new
sample of high z galaxies
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• Montecarlo simulations
• GRB rate follows SFR
• Powerlaw F(L)
• Instrumental thresholds BATSE, HETE2, SWIFT
• Constraints
• log N log P
• Epeak distribution
• XRF/GRB ratio

Data from Hopkins 2005
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GRB production by stars Higher efficiencyat
high z ?
(Daigne, Rossi Mochkovitch 2006)Metallicity
effect ? See e.g. E. Le Floch et al. 06One
needs to better understand the GRB progenitors.
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Very high redshift GRBs (zgt6) ?Probing the
reionization epoch (spectroscopy) ?Pop. III stars
?
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GRB ?
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GRBs cosmology measuring cosmological
parameters ?
Gamma-ray bursts are not standard candles?Eg,iso
1051 1054 erg ?Some correlations are used to
 standardize  GRBs Eg,iso vs Epeak large
dispersion Eg vs Epeak betterPBs
Eg is measured from the break time in the
afterglow
Epeak keV ? MeV
nFn
Amati et al. 2003
n
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q0
Obs
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q0
Obs
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Gamma-ray bursts are not standard candles?Eg,iso
1051 1054 erg ?Some correlations are used to
 standardize  GRBs Eg,iso vs Epeak large
dispersion Eg vs Epeak betterPBs Eg is
measured from the break time in the afterglow
difficult The physical interpretation is not
clear (chromatic/achromatic breaks) The number
of GRBs is too small to check the intrinsic
dispersion for a sample of GRBs at the same
redshift. ?Comparison to SNae Ia higher z ?
overcome the degeneracy pb
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Ghirlanda et al. 2005
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3. E-ELT and GRBs
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• GRB detection t0 satellite with real-time
  localization (1)t0 10s transmission to the
  ground large spectral range (Epeak)
• Afterglow detection t0 30s robotic telescope
  localization (1)t0 1-2 min real-time
  transmission infrared is needed
  (high-redshift / dust)
• (3) Afterglow follow-up t0 1-2min?weeks
  photometry (early times  small telescopes )t0
  1-2min?hours minimal spectroscopy
  redshift high-resolution spectroscopy (large
  telescopes) infrared is needed
  (high-redshift / dust)

SWIFT/XRT
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GRB 060418 Vreeswijk et al. 2007Trigger by
SWIFT/BAT t0 3 X-ray afterglow SWIFT/XRT
t01min 5 VLT/UVES using the  rapid
response mode  t010 min 1( a human
astronomer at t07 min to align theUVES slit
(1) on the afterglow)Spectra at t011, 16,
25, 41, 71 min resolving power 7 km/s S/N
10-15
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GRB 060418 Vreeswijk et al. 2007GRB z
1.490ISM time vaiability,better
understanding ofthe excitation mechanismof the
observed lines.
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GRB 060418 Vreeswijk et al. 2007GRB z
1.490ISM time variability,better
understanding ofthe excitation mechanismof the
observed lines.IGM three interveningMg II
systems z 0.603 z 0.656 z 1.107
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E-ELT proposed for 2020(1) which satellite
for the GRB detection SWIFT 2005 ? 2015
? GLAST 2008 ? 2018 ? (real-time localization
for HE only) SVOM 2012 ? 2022 ? (2) which
robotic telescopes for the afterglow detection
1 localization should not be an issue
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E-ELT proposed for 2020(1) which satellite
for the GRB detection(2) which robotic
telescopes for the afterglow detection 1
localization(3) E-ELT requirements ?
 rapid pointing  (lt 30 min) ?  rapid
response  (lt 30 min) ? spectroscopy alla
XSHOOTER UV?K (3 arms) R 4000-14000
fast response ? as far in infrared as
possible Without these requirements GRB
host galaxies
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E-ELT proposed for 2020(1) which satellite
for the GRB detection(2) which robotic
telescopes for the afterglow detection 1
localization(3) E-ELT requirements ?
 rapid pointing  (lt 30 min) ?  rapid
response  (lt 30 min) ? spectroscopy alla
XSHOOTER UV?K (3 arms) R 4000-14000
fast response ? as far in infrared as
possible(4) Impact of a large collecting area
? moderate-z GRBs excellent S/N ? high-z
GRBs detection of fainter sources ? study
of the host galaxy
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GRBs and cosmology ? ISM (host galaxy) ?
IGM (line of sight) ? SFR (biases ?) up
to z gt 6 (reionization epoch pop.
III) (expected GRB rate ?) ? cosmological
parameters (TBC) E-ELT and GRBs the large
collecting area improves the S/N and allows
to detected fainter sources. ? GRB detection
in space in 2020 ? Host galaxies no specific
requirements ? Afterglows - rapid
response / rapid pointing - fast
spectroscopy (VLT) (large spectral range
? IR) - location on Earth plays a
role
GRBs are a unique tool to probe the evolution of
the Universe from the first stars to the present
epoch.