GReat Bu’s GRBGReat Bu’s GRB

2004 / 112

GRBGRB

Early Mission Early Mission HistoryHistory

1960s, the Vela series

Burst And Transient Source Experiment (on the CGRO, launched in 1991)

BeppoSAX (launched in 1996/4/30)– provide a much more accurate location

HETE– failed in 1996

GRB910421

1967/7/2 the first observation1973 publish“Model burst”Distance:1)galactic disc ~102pc2)halo ~104pc3)cosmological ~Mpc

For now1)isotropic distribution2)redshift determination(~30 now)3)Angular distrubution

strong suggest a cosmological origion!!

Z-known GRBsZ-known GRBs

So….So….Huge energy Eiso~1051-54 erg

Rapid temporal variability on time scales of ms compact object

However, due to γ+γ e+ + e-

optical depth should be >> 1,

non-thermal spectrum optical thin

Compactness problem

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

The solution??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

1~ 1,for

:effect beaming

cos1

coscos

:light of aberration

'

'

v

GRB all starGRB all starGRB970228 Afterglow, x-ray ,optical counterpart, XT RT (a breakthrough)

GRB970508 Redshift ,absorption lines (FeII MgII), radio counterpart

GRB971214 Host galaxy

GRB980425 SN association(SN1998bw) (z=0.0085, the “closet”)

GRB990123 most energetic ( Eiso~3 X 1054erg ) optical counterpart (by ROTSE)

GRB030325 polarzation

GRB030329 SN association(SN2003dh)

mC

Emmmm )(

2212211

Adopt from SCIENCE@NASA

Summary of Summary of observationobservation

Observation (I) --Observation (I) --GRBGRB

Eiso

Burst rate

in 1991-2000 (CGRO operation period) 1/day (~1/106-7yr/galaxy)

Duration

T90:5%~95% in the 50-300keV

Observation (II) --Observation (II) --GRBGRB

Spectrum

Non-thermal

No clear observational evidence for the existence of spectral lines

Observation (III) -Observation (III) -afterglowafterglow

Lightcurves Well fitted by power-laws~5 GRB has line features in the early X-ray afterglow Some of them “Break” (low energy poewer index ~2)Offset from the center of the hot galaxyHost 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) Observation (IV) --afterglowafterglow

GRB/SN connection

red excess ,”SN bump”:

GRB980326, GRB011121

GRB980425 / SN1998bw : within the error box

GRB030329 / SN2003dh: very similar spectrum with that in SN1998bw case

“super” Type Ic

Types of SNeTypes of SNeaccording 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 redsiftSNIc Best fit : Z~0.95

Spectral evolution

Observation (V) -Observation (V) -afterglowafterglow

Polarization

MNRAS 309,L7 1999

Consider a magnetic field completelytangled in the plane of the shock front, but with a high degree of coherence in the orthogonal direction

Γ >>1, no polarization

Γ ~ 1/(θc+ θ0)

Γ <1/(θc- θ0) see only part of the circle centred on θ0

Γ 1 light aberration vanishes,The observe magnetic field is Completed tangled and Polarization disappears

Two maxima in the polarization light curve, the first forThe horizontial component and the second for the vertical one!!

GRB030325

Oh , Theory Oh , Theory

Model forestModel forestSGRs as a hint ??Relativistic dust crash energetically into the solar wind Comets falling onto NSsPrecessing jets from pulsarsCanonballs from supernovaeJet-disk in a binary systemMagnetar bubble collapseNS collapse to a strange starCollapse to a BH caused by accretionSupermassive BH formationEvaporating BHs

The “fireball” The “fireball” againagain

GRBs occur through the dissipation of the kinetic energy of a relativistic expanding fire ball

γ-ray emission mechanisms

The shape of The shape of thingsthings

Time variability (~milliesecond)

R~ CΓ∆T compact object

Duration 10-2s ~ 103s

Energy Eiso~1051-54 (for z-known GRBs)

Beaming

Rates , R~1/106-7yr/galaxy

if beamed…..

j

j

ddR

EE

j

isojet

0

2

0

2

sin2 ,4

R'

angle opening-half:

~2

The internal-external The internal-external modelmodel

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 GRBexternal forward shock afterglow

The “inner The “inner engine”engine”

Binary NS merge

WD-NS , NS-BH merge

failed supernova (Collapsar)

Collapsar Collapsar – a BH is bor– a BH is bornn

1993, by Woosley et al.

“Failed supernova”

Iron core collapse BH

MHD jet

ApJ 524:262 1999ApJ 524:262 1999

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.

Adopted from GSFC, NASA

Make story complete —Make story complete — asymmetric asymmetric supernova supernova

2000, by wheeler et al.

The generation of jets

Make story more complete —Make story more complete — Wolf-Reyet starWolf-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….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 Summary

Conclusion Conclusion Multi-origion

MHD

Gravitational wave

Polarization

TeV photon observation

GRB 970828 no OT, “dark burst”

be obscured by dust in their host galaxy

associated with massive sar formation??

The unified model??The unified model??astro-ph/0410728

Reference and Special Reference and Special ThanksThanks

Many of content are adopted from “Jochen Greiner Homepage” ( http://www.mpe.mpg.de/~jcg/ )Romanian Report in Phisics, Vol.56 No.2 P204, 2004 Valeriu Tudose et al.ASTRONOMY, October 2004Others….