gray Burst Physics

1
g-ray Burst Physics
E. Waxman Weizmann Inst. Israel
2
Bibliography

• A pedagogical discussion of the topics covered in
  the 1st lecture- general considerations
  fireball dynamics- is given in section 2 of
• Waxman 2003, Lec. Notes Phys. 598, 393
  astro-ph/0303517.
• The topics covered in the 2nd lecture- afterglow,
  progenitor clues current challenges- are
  presented in slides 9-37.
• Implications of afterglows discovered
  in the BeppoSax era are summarized in sections
  4 5 of Waxman 2003, Lec. Notes Phys. 598, 393
  astro-ph/0303517. For an update including
  implications of afterglows in the SWIF era see
  
• Meszaros 2006, Rep. Prog. Phys. 69,
  2259.
• A pedagogical review of the open
  questions related to the physics of relativistic
  collisionless shocks is given in
• Waxman 2006, PPCF 48B, 137
  astro-ph/0607353.
• A pedagogical discussion of the topics covered in
  the 3rd lecture- production of high energy
  protons and neutrinos in GRBs- is given in
  sections 4 5 of
• Waxman 2001, Lec. Notes Phys. 576, 122
  astro-ph/0103186.
• For a shorter discussion, updated to
  include implications of the most recent GRB and
  cosmic-ray observations, see
• Waxman 2006, AIPC 836, 589
  astro-ph/0703434.

3
A brief introduction
4
Early History

• Few secs bursts of
• MeV photons
• Discovery
• 1967 by VELA satellites
• (publication 1973)
• 1991 BATSE
• 1 GRB/day

5
BATSE phenomenology
Fishman Meegan 95

• T0.01 to 100 s
• Short T0.2 s, Long T20 s
• Variability Dt1 ms
• Non-thermal spectrum
• 1-- 100 MeV
• Most E _at_ e1MeV
• Isotropic sky distribution
• Cosmological origin
• d1028.5 cm ? Eg(z1)1053 erg

Winkler et al. 95
6
The fireball model
R(M/Msun) cm T10s Dt t(gg-ee-)1014 100
MeV gs Dv(Dt)c/2G2
Gravitational collapse of (few) solar mass to
BH T disk viscous time Relativistic
outflow G100 (c-vc/2G2) Internal shocks
at RG2cDt1012cm e- acceleration in
Collisionless shocks Synchrotron/IC emission of
gs
Paczynski 86 Goodman 86
Narayan, Paczynski, Piran 92 Meszaros Rees
94
7
Progenitors
Collapse of a massive star
(Collapsar)

• Progenitor
• Merger of a compact binary (NS-NS, NS-BH)

Goodman 86 Paczynski 86
Woosley 93 Paczynski 98
8
Prediction Afterglow
M on 1 Solar Mass BH 107cm
e- acceleration in Collisionless shocks
1012cm
G300
Collision with surrounding gas 1016cm
MeV gs Lg1052erg/s
e- Synchrotron/IC
X-ray, UV Radio
Paczynski Rhoads 93 Katz 94 Meszaros Rees
97 Vietri 97 Waxman 97 Sari, Piran Narayan
98
9
1997 BeppoSAX

• Arc-min localization for long bursts
• in 10hrs
• 1 / Month
• Detection of (predicted) X-ray,
• Optical Radio afterglow
• Identification of host galaxies
• Determination of redshift
• 2

Metzger et al. 97
10
Afterglow I. Dynamics
11
Relativistic Point explosion
E
G(R)
G
n
q
q
1/G
p
R
D

• gp,thermalG
• trfR/Gc
• DrfR/G

• EG2M(R,n)c2
• tR/c
• DR/G2
• tobsR/G2c, DtobsD/cR/G2c

Dtobsq2R/cR/G2c
12
Dynamics 101a
E
G(R)
n
q
q
1/G
R
Blandford McKee 76
Waxman 97
13
A comment on winds

• ISM

• Wind

14
Direct size measurement I. Scintillation
q
q d l
d
l
h
dne
Diffractive scintillation

• Finite size, cosmological source hcrit.few x
  1017cm

Frail, Waxman Kulkarni 00
15
II. Resolved source
Taylor et al. 04

• GRB 030329, 24 days after the burst (z0.17)
• VLBABonn at 22 GHz
• Marginally resolved at 0.08 milliarcsec
• Superluminal expansion _at_ 5c

0.45 x 0.18 mas
16
Dynamics 101b

• Ignorant jet/observer

G(R)1/qj
tcomovingR/Gc, DcomovingR/G 1/qj

• G(R)1/qj Sideways expansion

2qj
Rj
Rhoads 97, 99
17
Jet breaks
Staneck et al. 99 Harrison et al. 99
18
Standard g-ray energy!

• Total energy?

Frail et al. 01
19
Afterglow II. Radiation
20
Collisionless shocks
G
(nGn)
p
Relativistic shock
p
Ds
21
A phenomenological model

• Collisionless B generation, non-thermal
  particles
• ? synchrotron emission
• Open questions
• 1. B generation
• 2. Non-thermal e-

22
Synchrotron emission

• Model parameters E,n, ee, eB (,q)
• Characteristic freq.
• Peak flux

23
Synchrotron emission

• Cooling freq.
• Self-absorption

fm, nm, nc, na E,n, ee, eB,q
24
Observations Synchrotron spectrum
Wijers Galama 98

• Model parameters
• E,n,p,ee,eB
• Qualitative agreement
• f(t,n)A ta(p) nb(p)
• Observables
• fm, nm, nc, na
• Typical values
• E1052erg, n1/cm3, p2.2-0.1, eeeB0.1
• Not too many examples!

Waxman 97 Freedman Waxman 01
25
The challenges I. B

• UB,up10-9 nmpc2
• eB0.1 ? UB,down/ UB,up 108
• EM instabilities (ala Weibel) may give eB0.1
• with lB c/wp
• But DR/G Gct 1017cm c/wp107cm
• Avoid field dissipation
• ? lB lsd _at_ downstream!

Gruzinov Waxman 99 Medvedev Loeb 99
Gruzinov Waxman 99 Gruzinov 01
26
Challenges II. Particle acceleration

• e- coupling (ee0.1 )
• dne/dgege-2
• p acceleration to UHE?

27
Fireball calorimetry
28
Non-relativistic transition

• Shock becomes sub-rel. at
• At later time

29
Synchrotron emission at NR transition

• ISM

• Wind

• Non. Rel. spherical (SS-SNT)

E,n, ee, eB
30
Fireball calorimetry

• Sub-relativistic _at_ 1yr,
• Isotropic radio emission.
• Long term radio observations
• Determine total fireball E

Frail, Waxman Kulkarni 00 Livio Waxman
01 Granot Loeb 03
31
GRB 970508
Berger et al. 04
32
Calorimetry Implications

• Explosion energy
• E1051-0.5 erg
• Radius R1017.5 cm
• Consistent with relativistic phase evolution
  (E,R,qj)
• Eg10 E ?
• Standard E ?

Frail, Waxman Kulkarni 00 Berger et al. 04
33
Current StatusPost SWIFT Open Questions
34
SWIFT Afterglows

• (100 long, 10 short) / yr
• Rapid- 1 min- follow up
• I. Short GRBs
• 12 Short GRBs, 9 X-ray AG, 6 optical AG
• 0.3 ? 30 times fainter than long GRBs
• 0.2s g-rays followed by 100s softer emission
• Faint afterglows ?
• weak constraints on parameters (n, q, )

35
SWIFT Afterglows

• II. Challenges
• Collisionless shock physics (ee, eB )
• Missing X-ray afterglow _at_ 10min10hr
• No jet breaks??
• X-ray flares
• Long- dt/t
  103s?
• Short- (050709) 1045erg, dt1hr _at_ t16day

36
Back to the engine
Collapse of a massive star
(Collapsar)

• Progenitor
• Merger of a compact binary (NS-NS, NS-BH)

Goodman 86 Paczynski 86
Woosley 93 Paczynski 98
37
Progenitor clues Long GRBs

• Long GRBs in star-forming regions,
• Brightest regions of host galaxies
• ? Young population? massive stars (?)
• 4 GRBs associated with SN-Ic
• ? All long GRBs are from SN-Ics (?)
• Difficulties
• All 4 at low z (
• for 3 of 4- Eiso
• 060505 (z0.089) 060614 (z0.125) No SN

38
Progenitor clues Short GRBs

• 3 in elliptical galaxies 2 in star-forming
• ? Old population? mergers?
• Lower E lower E available in mergers?

39
GRBs as Particle accelerators
40
The acceleration challenge
v
R
/G
B
v
2R
G2
G2
l R/G
(dtRFR/Gc)
Waxman 04
41
The suspects

• Active Galactic Nuclei (steady)
• G few requires L1047 erg/s
• Few, brightest AGN
• Gamma Ray Bursts (transient)
• G 300 requires L1051 erg/s
• Average Lg1052 erg/s

42
Proton/electron acceleration

• Protons
• Acceleration/expansion
• Synchrotron losses
• Particle spectrum
• p energy production

• Electrons
• MeV gs
• Optical depth
• g spectrum
• g energy production

Afterglow
0.02
52
Waxman 95
Waxman 04
43
Flux Spectrum Model
1019eV

• Galactic heavy nuclei X-Galactic
  protons
• X-Galactic protons
• Generation spectrum
• rate (z evolution follows SFR)
• Flys Eye fit JGE-3.50

Watson 91, Nagano Watson 00
Waxman 95 Bahcall Waxman 03
44
Flux Spectrum Model vs. Data
X-G Model
Ruled out 7s
5s
Bahcall Waxman 03
45
Data/Model consistency

• Yakutsk, Flys Eye, HiRes Consistent with
• XG protons
  GZK
• AGASA (25 of total exposure)
• Consistent below 1020eV
• Excess above 1020eV 2.2/-0.8 8
  observed
• New source/New physics/ 25 energy
  
• Local inhomogeneity
  over-estimate
• Need Large, hybrid 1018eV to 1020eV detector
  (Auger)

?
46
GZK sphere

• AGN, Radio-galaxies ?
• GRBs ?
• For RGRB(z0)0.5/Gpc3yr
• Prediction

g
p
D
lB
Waxman 95 Miralda-Escude Waxman 96, Waxman 03
47
GRB Model Predictions

• 3x1020eV
• Few, narrow spectrum sources
• Fluctuations (no homogeneous GZK).
• Auger
• AGASA multiplets-
• statistical significance?

Watson 91, Cronin 93
Miralda-Escude Waxman 96
Teshima 03 Finley Westerhoff 04
48
Generic GRB ns

• Weak dependence on model parameters

Waxman Bahcall 97, 99 Guetta, Spada Waxman
01