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What GRBs can bring to Particle Astrophysics
(and vice-versa) ?
Bruce Gendre LAM/OAMP
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The Gamma-Ray Burst phenomenon

• Sudden and unpredictable bursts of hard X and
  soft ? rays
• Typical durations of tens of seconds
• Cosmological origin
• Typical isotropic energy 1051 to 1054 erg

Different and unclassifiable light curves

• Non thermal and fast evolving spectra
• Described by an empirical smoothly broken
  power-law (Band law)
• Peak energy of the ?F? spectrum Ep

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The Gamma-Ray Burst phenomenon

• In 1997 BeppoSAX discovered a fading emission
  following the GRB (Costa et al. 1997)
• Observed at all wavelengths (radio to X-ray)
• Detectable for days to weeks.
• A burst the sum of two phenomena
• the classical GRB phenomenon , the prompt
  emission
• the subsequent fading emission, the afterglow
  emission

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The fireball model
External Shock
Rees Meszaros 1992
Interstellar medium
FS
RS
1012 cm
1014 cm
1017 cm
ms time variability compact source huge amount
of energy plasma in ultra-relativistic (? gt
100) expansion
kinetic energy loaded in relativistic electrons
and magnetic fields (plus few lost in fireball
baryon load)
external layers of progenitor ejected as shells
with different velocities Internal Shocks
Shells interaction with the external medium
External Shock
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GRB progenitors
ms time variability implies a compact object
Energy gt 1052 erg Stellar mass black hole

• Forming a black hole
• Merging of two compact objects SHORT GRB (lt2s)
• Gravitational collapse of a massive star (Mgt 20
  M?) LONG GRB (gt2s)

Woosley McFadyen 1999 Heger et al. 2001
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Progenitor distance

• Long GRB death of massive star
• Possible early after big-bang
• Low metalicity environment
• Distant events !
• Mean redshift 2.5 (Jakobsson et al. 2006)
• Potentially the most distant object visible
  within the Universe

• Short GRB collapse of compact object binary
• Need to form the 2 compact objects (possible
  early after big-bang)
• Need to radiate binding energy (long time)
• Nearby events !
• Mean redshift 0.5 (Ghirlanda et al. 2006)

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To sum up the problem
You observe this
And you want to know the detonator model and the
color of the connectors
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Gravitational waves produced by GRBs

• Gravitational waves can be produced
• Before the collapse of the binary progenitor
  (efficient)
• During the bounding of the core-collapse
  (inefficient)
• Main target are short bursts

To date, no detection Due to small volume sampled
(detection limit is 100 Mpc)
z 0.02
Z 2

• Next step advanced instruments, LISA
• Should trigger on GRBs
• Will provide information on the progenitor mass,
  geometry.

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Neutrinos produced by GRBs

• Neutrinos can be produced by
• The progenitor (like in SNe)
• The acceleration process

• Neutrino large observatories still under
  construction / commissioning / calibration
• At the moment, no claimed detection of neutrinos
  from GRBs
• Can give insights on the progenitor and the
  acceleration

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Cosmic rays produced by GRBs

• During the acceleration of the fireball, baryons,
  electrons and positrons are accelerated up to
  relativistic velocities
• Possible candidate to produce energetic CRs
• But not clear if GRB produce detected CRs

To date, no claimed detection from any GRB (but
we detect only 40 of GRBs seen on-axis, and
none can be seen off-axis !)
Work still is progress !
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High energy photons
Previous observational evidences of high energy
emission in GRBs

• GRB 940217 (Hurley et al. 1994) detected by
  EGRET, with a 18 GeV photon
• GRB 941017 (Gonzalez et al. 2003)
• GRB 090514B (AGILE collaboration) detected in
  the GRID, work still in progress

• However, no clear idea of what happen after a few
  MeV.
• Unknown GRB sky above 100 GeV.
• Waiting for GLAST !!

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GRB and cosmology

• GRBs can be used to study cosmology
• Distant events
• Present empirical relations
• Good complement to SNe
• But
• No nearby event to calibrate any standard
  candle
• Actual solutions
• Do not care (may be problematic)
• Use sample of same distant events (statistical
  significance still low)
• Try to understand the empirical standard
  candles (complicated, but accurate)

Ghirlanda et al. 2004
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Prompt cosmology
GRB, SNe, and CMB constraints are not
similar Strong constraint on the cosmological
parameters (Ghirlanda et al. 2007, Firmani et al.
2006b, Amati et al. 2008)
SNIa
CMB
GRB

• GRBs are visible up to large distance
• Good indicator of re-ionization state (e.g.
  Totani et al. 2006)
• Information on metalicity at high redshift (e.g.
  Kawai et al. 2005)
• Beacon for non-radiating material within the
  line of sight, such as WHIM
• Set the death time of pop III stars
• Estimation of distance (Pelangeon Atteia 2008)

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Afterglow cosmology the Boër Gendre relation
Relation linking the flux of X-ray afterglow with
the date of the observation
Gendre, Galli, Boer, 2008 Before referee comments
Group xI bright afterglows
Group xII dim afterglows
Group xIII Outliers (GRB 980425, 031203, 060218,
060512)
Probability of spurious clustering 3.6 x 10-8
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Estimation of the redshift

• For GRBs of group xI and xII, we can estimate the
  redshift needed for being compliant with the BG
  relation
• Proof on the bursts defining the relation
• Easy to do we know the group of each event

• Very good matching between the measured and
  estimated redshifts
• Deviation at low redshift

Method not valid for nearby GRBS (z lt
0.5) Uncertainty on the redshift is 30 ,
sometime more
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Conclusions

• GRBs can produce
• Gravitational waves
• Neutrinos
• Ultra high energy photons
• High energy cosmic rays
• All these messengers arrive directly from the
  central engine
• Strong constraints to be set on the central
  engine properties
• But once the instruments will be powerful enough
  !
• GRBs can also help with cosmology
• Constraints on the cosmologic parameters
• Measurement of the distance
• Information on the date of re-ionization and
  formation of first stars

So please continue building new and larger
instruments we would be very happy to have
these information for our models !!