Bruce GendreLAM/OAMP

What GRBs can bring to Particle Astrophysics (and vice-versa) ?

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 νFν spectrum Ep

The Gamma-Ray Burst phenomenon

Sudden and unpredictable bursts of hard X and soft γ rays

• Typical durations of tens of seconds

• Cosmological origin

• Typical isotropic energy: 1051 to 1054 erg

prompt

afterglow

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”

The Gamma-Ray Burst phenomenon

The fireball model

Interstellar medium

external layers of progenitor ejected as shells with different velocities : Internal Shocks

Shells interaction with the external medium : External Shock

FSRS

ms time variability : compact sourcehuge amount of energy : plasma in ultra-relativistic ( > 100) expansion

1012 cm1014 cm

Internal Shocks

1017 cm

External Shock

kinetic energy loaded in relativistic electrons and magnetic fields (plus few lost in fireball baryon load)

Rees & Meszaros 1992

GRB progenitors

ms time variability implies a compact object

Forming a black hole• Merging of two compact

objects : SHORT GRB (<2s)

• Gravitational collapse of a massive star (M> 20 M) : LONG GRB (>2s)

Energy > ~1052 erg : Stellar mass black hole

Woosley & McFadyen 1999; Heger et al. 2001

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)

To sum up the problem

You observe this

And you want to know the detonator model and the color of the connectors

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

z = 0.02

Z = 2

To date, no detectionDue to small volume sampled (detection limit is ~ 100 Mpc)

Next step : advanced instruments, LISA

• Should trigger on GRBs• Will provide information on the progenitor mass, geometry.

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

)(np

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AMANDA/IceCube South Pole

ANTARES Mediterranean Sea

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 !

High energy photons

• 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

Previous observational evidences of high energy emission in GRBs:

However, no clear idea of what happen after a few MeV.

• Unknown GRB sky above 100 GeV.• Waiting for GLAST !!

GRB and cosmology

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GRBs

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)

Supernovae

Ghirlanda et al. 2004

Pelangeon et al. 2006

Prompt cosmology

GRBGRBCMBCMB

SNIaSNIa

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)

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)

Group xIbright afterglows

Group xIIdim afterglows

Group xIIIOutliers(GRB 980425, 031203, 060218, 060512)

Probability of spurious clustering : 3.6 x 10Probability of spurious clustering : 3.6 x 10-8-8

Gendre, Galli, Boer, 2008Before referee commentsGendre, Galli, Boer 2008After referee commentsNow 64 events

Relation linking the flux of X-ray afterglow with the date of the observation

Broadening due to uncertainties on the prompt end

Now 8 outliers

Afterglow cosmology : the Boër & Gendre relation

Estimation of the redshift

Method not valid for nearby GRBS (z < 0.5)Uncertainty on the redshift is ~ 30 %, sometime more

For GRBs of group xI and xII, we can estimate the redshift needed for being compliant with the B&G 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

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