The ‘Dark Side’ ‘Dark Side’ of Gamma-Ra y Bursts and Implications for Nucleos ynthesis neutron capture elements (‘n-process’) light elements (spallation?) ApJ (2003) 595, 294 Susumu Inoue Nucleosynthesis in Baryon-Rich Outflows Associated with GRBs in collaboration with Nobuyuki Iwamoto (U. Tokyo) Manabu Orito (Tokyo Inst. Tech.) Mariko Terasawa (CNS) ‘ ‘ Dark Side’ Dark Side’
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‘Dark Side’ The ‘Dark Side’ of Gamma-Ray Bursts and Implications for Nucleosynthesis neutron capture elements (‘n-process’) light elements (spallation?)
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The ‘Dark Side’‘Dark Side’ of Gamma-Ray Burstsand Implications for Nucleosynthesis
neutron capture elements (‘n-process’)light elements (spallation?)
ApJ (2003) 595, 294
Susumu Inoue
Nucleosynthesis in Baryon-RichOutflows Associated with GRBs
massive star core collapse, compact binary, etc… →
hot T0>~MeV, thick ~e≫1,n-rich initial conditions→ expansion→ nucleosynthesis?
GRB jet → limited nucleosynthesis (small amounts of D,4He)Lemoine 02, Pruet, et al 02, Beloborodov 03
entropy/baryon s/kb=4mpc2/3T0~1250T0/1MeV
dimensionless entropy 〜 final Lorentz factor=L/Mc2
.
baryon-rich outflow(BRO)
≪ → much more interesting! (n-capture elements, up to Pt, Au, U?)
evidence for the dark sidedark side of GRBs (baryon-rich outflows)numerical simulations of jet propagation in collapsars Zhang, Woosley & Heger ‘03
significant energy in peripheral, low outflow → X-ray flashes, statistics of afterglow light curve breaks
evidence for the dark sidedark side of GRBs (baryon-rich outflows)observations! of low outflow in GRB030329/SN2003dh Berger et al. ‘03, Nature, 426, 154
dominant energy in peripheral, low (~a few) outflow → dark energy rules (at least in some GRBs) !
evidence for the dark sidedark side of GRBs (baryon-rich outflows)numerical simulations of jet propagation in collapsars Zhang, Woosley & Heger ‘03
example of failed GRB → GRB-less hypernovae?
parametersL=1052 erg/s luminosityr0=107 cm central engine radius
=L/Mc2 dimensionless entropyYe=(nn/np+1)-1
initial electron fraction
.
log t’ [s] (comoving time)
log
T [M
eV]
=2
=102
=10
=103
T
0
2
4
6
-2
-4
-6
-6 -5 -4 -3 -2 -1
log
[g
cm
-3]
fireball &T profile(comoving frame trajectory)
exponential
power-law
start from the simplest dynamical model:spherical, adiabatic, freely expandingthermally-driven steady flow
choose 2 (M~10-2M◎)relativistic limit,validity of fireball model
parametersL=1052 erg/s luminosityr0=107 cm central engine radius
=L/Mc2 dimensionless entropyYe=(nn/np+1)-1
initial electron fraction
.
log t’ [s] (comoving time)
log
T [M
eV]
=2
=102
=10
=103
T
0
2
4
6
-2
-4
-6
-6 -5 -4 -3 -2 -1
log
[g
cm
-3]
fireball &T profile(comoving frame trajectory)
exponential
power-law
start from the simplest dynamical model:spherical, adiabatic, freely expandingthermally-driven steady flow
choose 2 (M~10-2M◎)relativistic limit,validity of fireball modelnuclear reaction network
>3000 n-rich speciesinclusion of light n-rich nuclei(Terasawa et al. ‘01)crucial for n-rich, rapid expansion
=100, Ye=0.4
T9
D2
He4
np
B11Be9
T3
He3
Li7
s/kb~105, 0~ 3 103 g/cm3
• some D, 4He production• freezeout t’>~1ms not very exciting…
D2
He4
n
p
B11
Be9
T3
He3
Li7
• reactions continue, t’>~100s, A>16 and beyond• late D production by n decay → p(n,)d a lot more interesting!
=2, Ye=0.4 s/kb~2500, 0~ 2 105 g/cm3
Ye=0.1, =2
• near r-process (n-dripline) path• flow > 3rd peak → fission cycling?• abundance at peaks Y1<<Y2~Y3~10-6, neutrons remaining
s/kb~20000~ 2 105 g/cm3
NS mergers? high M, low disks?.
Ye=0.4, =2
• intermediate path > 2nd peak• small flow > 3rd peak• abundance at peaks Y1~10-7,Y2~10-6,Y3~10-8, neutrons remaining
• production up to actinides for Ye<~0.4 → fission cycling?• peaks intermediate between r & s (n-process)• abundances at peaks Yp~10-6 for Ye<~0.4; small flow to high A for Ye~0.5• neutrons always remaining → external n-capture process?
Summary low baryon-rich outflows (the dark side) of GRBs
• synthesize heavy n-capture elements up to the actinides induce ‘n-process’ (intermediate between r & s)• synthesize some light elements D, Li, Be, B much more by spallation?
baryon-poor, ultrarelativistic outflows (successful GRBs): not much happens…
heavy n-capture elements possibly observable in:Galactic abundances, metal poor starsBH binary companions → probe of GRB central engine conditions?
baryon-rich, mildly relativistic outflows (circum-jet winds or failed GRBs) can:
observational implications
Something interesting may be going on in places not readily seen!
• energetically important (often dominant)• interesting for nucleosynthesis