GRB GReat Bus GRB 2004 112 Early Mission

GRB GReat Bu’s GRB 2004 / 112

Early Mission History 1960 s, the Vela series Burst And Transient Source Experiment (on the CGRO, launched in 1991) Beppo. SAX (launched in 1996/4/30)– provide a much more accurate location HETE– failed in 1996

GRB 910421

1967/7/2 the first observation 1973 publish “Model burst” Distance: 1)galactic disc 2)halo 3)cosmological ~102 pc ~104 pc ~Mpc For now 1)isotropic distribution 2)redshift determination(~30 now) 3)Angular distrubution strong suggest a cosmological origion!!

Z-known GRBs

So…. Huge energy Eiso~1051 -54 erg Rapid temporal variability on time scales of ms compact object However, due to γ+γ e+ + eoptical depth should be >> 1, non-thermal spectrum optical thin Compactness problem

The “fire ball” Large concentration of electromagnetic radiation in small region of space with small fraction of baryons Sudden release of high intensity gammarays produces e+e- pairs which create an opaque photon-lepton “fireball”

The solution? ? The relativistic motion ( with Γ≧ 100 ) of the emitting region GRB are produced when an UR energy flow is converted to radiation in an optically thin region

GRB all star GRB 970228 Afterglow, x-ray , optical counterpart, XT RT (a breakthrough) GRB 970508 Redshift , absorption lines (Fe. II Mg. II), radio counterpart GRB 971214 Host galaxy GRB 980425 SN association(SN 1998 bw) (z=0. 0085, the “closet”) GRB 990123 most energetic ( Eiso~3 X 1054 erg ) optical counterpart (by ROTSE) GRB 030325 polarzation GRB 030329 SN association(SN 2003 dh)

Adopt from SCIENCE@NASA

Summary of observation

Observation (I) --GRB Eiso Burst rate in 1991 -2000 (CGRO operation period) 1/day (~1/106 -7 yr/galaxy) Duration T 90: 5%~95% in the 50 -300 ke. V

Observation (II) --GRB Spectrum Non-thermal No clear observational evidence for the existence of spectral lines

Observation (III) -afterglow Lightcurves Well fitted by power-laws ~5 GRB has line features in the early Xray afterglow Some of them “Break” (low energy poewer index ~2) Offset from the center of the hot galaxy Host galaxy (025~Z~4. 5): are typically low mass, faint galaxies (R~25) with active star formation region

several re-brightenings, varying power law indices

Observation (IV) -afterglow GRB/SN connection red excess , ”SN bump”: GRB 980326, GRB 011121 GRB 980425 / SN 1998 bw : within the error box GRB 030329 / SN 2003 dh: very similar spectrum with that in SN 1998 bw case “super” Type Ic

Types of SNe according to the spectrum with H = SN II without H = SN I with Si = SN Ia without Si but with He = SN Ib without Si and without He = SN Ic The energy source for SN Ia is nuclear; for the others is gravitational

The lack of a measured redsift SNIc Best fit : Z~0. 95

Spectral evolution

Observation (V) -afterglow Polarization MNRAS 309, L 7 1999 Consider a magnetic field completely tangled in the plane of the shock front, but with a high degree of coherence in the orthogonal direction

Γ 1 light aberration vanishes, The observe magnetic field is Completed tangled and Polarization disappears Γ ~ 1/(θc+ θ 0) Γ <1/(θc- θ 0) see only part of the circle centred on θ 0 Γ >>1, no polarization Two maxima in the polarization light curve, the first for The horizontial component and the second for the vertical one!!

GRB 030325

Oh , Theory

Model forest SGRs as a hint ? ? Relativistic dust crash energetically into the solar wind Comets falling onto NSs Precessing jets from pulsars Canonballs from supernovae Jet-disk in a binary system Magnetar bubble collapse NS collapse to a strange star Collapse to a BH caused by accretion Supermassive BH formation Evaporating BHs

The “fireball” again GRBs occur through the dissipation of the kinetic energy of a relativistic expanding fire ball γ-ray emission mechanisms

The shape of things Time variability (~milliesecond) R~ CΓ∆T compact object Duration 10 -2 s ~ 103 s Energy Eiso~1051 -54 (for z-known GRBs) Beaming Rates , R~1/106 -7 yr/galaxy if beamed…. .

The internal-external model Time-varying outflow makes different Γ(>100) shells

When a faster shell catch up with a slower one: Kinetic energy internal energy (internal shock ) radiation (accelerated electrons interact with the ambient magnetic field ) internal shock GRB external forward shock afterglow

The “inner engine” Binary NS merge WD-NS , NS-BH merge failed supernova (Collapsar)

Collapsar – a BH is born 1993, by Woosley et al. “Failed supernova” Iron core collapse BH MHD jet

Ap. J 524: 262 1999

Adopted from GSFC, NASA The jet is erupting through the surface of the star. Blue represents regions of low mass concentration, red and yellow are denser. Note the blue and red striations behind the head of the jet. These are bounded by internal shocks.

Make story complete — asymmetric supernova 2000, by wheeler et al. The generation of jets

Make story more complete — Wolf-Reyet star Wolf-Rayet stars are hot (25 -50, 000+ degrees K), massive stars (20+ solar mass) with a high rate of mass loss. Strong, broad emission lines (with equivalent widths up to 1000Å!) arise from the winds of material being blown off the stars. Wolf-Rayets stars are divided into 3 classes based on their spectra, WN stars (nitrogen dominant, some carbon), WC stars (carbon dominant, no nitrogen), WO stars with C/O < 1.

The whole story…. To make a collapsar need three essential components: 1)Wolf-Rayet star 2)A rotating stellar core 3)A core collapse that failed to produce a successful supernova

Summary

Conclusion Multi-origion MHD Gravitational wave Polarization Te. V photon observation GRB 970828 no OT, “dark burst” be obscured by dust in their host galaxy associated with massive sar formation? ?

The unified model? ? astro-ph/0410728

Reference and Special Thanks Many of content are adopted from “Jochen Greiner Homepage” ( http: //www. mpe. mpg. de/~jcg/ ) Romanian Report in Phisics, Vol. 56 No. 2 P 204, 2004 Valeriu Tudose et al. ASTRONOMY, October 2004 Others….