Bruce Gendre LAM/OAMP

1. What GRBs can bring to Particle Astrophysics (and vice-versa) ? Bruce Gendre LAM/OAMP

2. The Gamma-Ray Burst phenomenon • Sudden and unpredictable bursts of hard X and soft γrays • 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 νFν spectrum Ep

3. prompt afterglow 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”

4. Internal Shocks The fireball model External Shock Rees & Meszaros 1992 Interstellar medium RS FS 1012 cm 1014 cm 1017 cm ms time variability : compact source huge amount of energy : plasma in ultra-relativistic ( > 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

5. GRB progenitors ms time variability implies a compact object Energy > ~1052 erg : Stellar mass black hole • Forming a black hole • Merging of two compact objects : SHORT GRB (<2s) • Gravitational collapse of a massive star (M> 20 M) : LONG GRB (>2s) Woosley & McFadyen 1999; Heger et al. 2001

6. 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)

7. To sum up the problem You observe this And you want to know the detonator model and the color of the connectors

8. 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.

9. ANTARES Mediterranean Sea AMANDA/IceCube South Pole 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

10. 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 !

11. 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 !!

12. GRB and cosmology GRBs Supernovae Luminosity distance redshift • 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

13. Pelangeon et al. 2006 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)

14. Gendre, Galli, Boer 2008 After referee comments Now 64 events Now 8 outliers Broadening due to uncertainties on the prompt end 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

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

16. 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 !!