Upload
others
View
10
Download
0
Embed Size (px)
Citation preview
Neutrinos and Explosive Nucleosynthesis
Gabriel Martínez Pinedo
Neutrinos in Cosmology, in Astro-, Particle- and Nuclear Physics
Erice, Sicily, September 21, 2009
Introduction Nucleosynthesis in supernova neutrino ejecta Accretion disks in collapsar models r-process Summary
Outline
1 IntroductionNucleosynthesis processes
2 Nucleosynthesis in supernova neutrino ejectaImpact neutrino interactionsThe νp process
3 Accretion disks in collapsar models
4 r-process
5 Summary
Introduction Nucleosynthesis in supernova neutrino ejecta Accretion disks in collapsar models r-process Summary
Stellar nucleosynthesis processes
In 1957 Burbidge, Burbidge, Fowler and Hoyle and independently Cameron,suggested several nucleosynthesis processes to explain the origin of theelements.
Ni (Z=28)
Sn (Z=50)
Pb (Z=82)
2 8
2028
50
82
126
162
184
νp-process“neutrino-proton process”rp-process“rapid proton process” via unstable proton-rich nuclei through proton capture
r-process“rapid process” viaunstable neutron-rich nuclei
Proton dripline(edge nuclear stability)
Neutron dripline(edge nuclear stability)
s-process“slow process” via chain of stable nuclei throughneutron capture
Fusion up to iron
Number of neutrons
Nu
mb
er o
f p
roto
ns
Big Bang Nucleosynthesis
BBFH suggested that neutron deficient nuclei are produced by proton captures
in an evironment with proton densities of 102 g cm−3 and T ∼ 2–3 GK.
Introduction Nucleosynthesis in supernova neutrino ejecta Accretion disks in collapsar models r-process Summary
Nucleosynthesis beyond iron
Three processes contribute to the nucleosynthesis beyond iron:s-process, r-process and p-process (γ-process).
30
40
50
60
70
80
40 60 80 100 120
Z
N
p-drip
n-drip
10-6
10-5
10-4
10-3
10-2
10-1
100
101
102
80 100 120 140 160 180 200
Ab
undan
ces
[Si=
10
6]
A
180Ta
m
138La
ssr
r
p
152Gd
164Er
115Sn 180
W
s-process: relatively low neutron densities, τn > τβ
r-process: large neutron densities, τn < τβ.
p-process: photodissociation of s-process material.
Introduction Nucleosynthesis in supernova neutrino ejecta Accretion disks in collapsar models r-process Summary
Nucleosynthesis beyond iron
p-process fails to explain the solar abundances of 92,94Mo and 96,98Ru[Arnould & Goriely, Phys. Rep. 384 (2003) 1]
Can supernova proton-rich ejecta be a site for the synthesis of of 92,94Moand 96,98Ru and Ru?
Introduction Nucleosynthesis in supernova neutrino ejecta Accretion disks in collapsar models r-process Summary
Explosive NucleosynthesisMain processes:
νe + n� p + e−ν̄e + p� n + e+
Neutrino interactions determine theproton to neutron ratio.Proton rich ejecta〈Eν̄e〉 − 〈Eνe〉 < 4(mn −mp) ≈ 5.2 MeV
νp-process (proton-richejecta).
r-process (neutron-rich ejecta)
α, n
α, p α, p, nuclei
α, n, nuclei
R in
km
102
103
104
105
Rν
31.4
He
Ni
Si
PNS
ORns ~10
Neutrino cooling and
Neutrino-driven wind
n, p
νp-process
r-process
M(r) in M
νe,µ,τ, νe,µ,τ
νe,µ,τ, νe,µ,τ –
Introduction Nucleosynthesis in supernova neutrino ejecta Accretion disks in collapsar models r-process Summary
Evolution of neutrino fluxes and energies: Ye
Fischer et al, arXiv:0908.1871, have performed the first Boltzmannneutrino transport study of the proto-neutron star evolution.
0 1 2 3 4 5 6 7 8 9 100
1
2
3
4
5(a) 10 solar mass
Time After Bounce [s]
Lum
inos
ity [1
051 e
rg/s
]
ν
e
anti−νe
0 1 2 3 4 5 6 7 8 9 100
1
2
3
4
5(b)
Time After Bounce [s]
Lum
inos
ity [1
051 e
rg/s
]
νµ/τ
anti−νµ/τ
0 1 2 3 4 5 6 7 8 9 108
10
12
14
16
18(c)
Time After Bounce [s]
rms
Ene
rgy
[MeV
]
νe
anti−νe
νµ/τ
0 1 2 3 4 5 6 7 8 9 100
1
2
3
4
5(a) 18 solar mass
Time After Bounce [s]
Lum
inos
ity [1
051 e
rg/s
]
ν
e
anti−νe
0 1 2 3 4 5 6 7 8 9 100
1
2
3
4
5(b)
Time After Bounce [s]
Lum
inos
ity [1
051 e
rg/s
]
νµ/τ
anti−νµ/τ
0 1 2 3 4 5 6 7 8 9 108
10
12
14
16
18(c)
Time After Bounce [s]
rms
Ene
rgy
[MeV
]
νe
anti−νe
νµ/τ
0 1 2 3 4 5 6 7 8 90.49
0.51
0.53
0.55
0.57
0.59
0.61
0.63
0.65
Time after bounce [s]
Ele
ctro
n F
ract
ion,
Ye
Boltzmann~(Lν,< εν >)
~(λν, λanti−ν )
Ejecta is always proton-rich
Introduction Nucleosynthesis in supernova neutrino ejecta Accretion disks in collapsar models r-process Summary
How well is the neutrino spectrum known?
Neutrino spectrum and luminosities are determined by the neutrinointeractions with matter in the protoneutron star atmosphere. Presence of lightnuclei results in important changes in the average energies of the emittedneutrinos. [A. Arcones, et al., PRC 78, 015806 (2008)]
Light nuclei are more abundant than protons
1081091010101110121013
Density (g cm−3)
10−4
10−3
10−2
10−1
100
Mas
s F
ract
ion
n
p
2H
3H
4He
3He
νe νe
Major contributors to opacity:
νe + n→ e− + p
νe opacity is independent of EoS.However, for ν̄e:
ν̄e + d → e+ + n + nν̄e + d → ν̄e + n + pν̄e + t → e+ + n + n + nν̄e + t → ν̄e + p + n + n
instead of
ν̄e + p→ e+ + n
Introduction Nucleosynthesis in supernova neutrino ejecta Accretion disks in collapsar models r-process Summary
How well is the neutrino spectrum known?
Neutrino spectrum and luminosities are determined by the neutrinointeractions with matter in the protoneutron star atmosphere. Presence of lightnuclei results in important changes in the average energies of the emittedneutrinos. [A. Arcones, et al., PRC 78, 015806 (2008)]
Impact in the energies of neutrinos and Ye
2 4 6 8 10Time (s)
10
15
20
25
Ave
rage
Ene
rgy
(MeV
)
Without light nucleiWith light nuclei
2 4 6 8 10Time (s)
0.44
0.46
0.48
0.5
0.52
Ye
νe
νe
Boltzmann transport calculations are necessary for an accurate estimate of the
effect.
Introduction Nucleosynthesis in supernova neutrino ejecta Accretion disks in collapsar models r-process Summary
Impact neutrino interactions in proton-rich ejecta
Neutrino interactions are responsible for the production of nuclei withA > 64
40 45 50 55 60 65 70 75 80 85 90 95 100Mass Number A
100
101
102
103
104
Yi/Y
i,⊙
Without νWith ν
Introduction Nucleosynthesis in supernova neutrino ejecta Accretion disks in collapsar models r-process Summary
The νp process
Proton rich matter is ejectedunder the influence of neutrinointeractions.
Nuclei form (mainly N = Z) atdistances where a substantialantineutrino flux is present.
Antineutrino charge-currentcapture time and expansion timescale are similar (∼ 1 s)
Neutrinos speed-up matter flowν̄e + p→ e+ + nn + 64Ge→ 64Ga + p64Ga + p→ 65Ge . . .
These reactions constitute the νp-processC. Fröhlich, et al., PRL 96, 142502 (2006)
As65
(p, )γpS −74 keV≈
64Ge
β+
64Ga
63.7 s
Introduction Nucleosynthesis in supernova neutrino ejecta Accretion disks in collapsar models r-process Summary
The νp process
Proton rich matter is ejectedunder the influence of neutrinointeractions.
Nuclei form (mainly N = Z) atdistances where a substantialantineutrino flux is present.
Antineutrino charge-currentcapture time and expansion timescale are similar (∼ 1 s)
Neutrinos speed-up matter flowν̄e + p→ e+ + nn + 64Ge→ 64Ga + p64Ga + p→ 65Ge . . .
These reactions constitute the νp-processC. Fröhlich, et al., PRL 96, 142502 (2006)
As65
64Ge
64Ga
n,p( )
65Ge
66As
(p, )γ
(p, )γ
~ 1 s
Introduction Nucleosynthesis in supernova neutrino ejecta Accretion disks in collapsar models r-process Summary
The νp process
Proton rich matter is ejectedunder the influence of neutrinointeractions.
Nuclei form (mainly N = Z) atdistances where a substantialantineutrino flux is present.
Antineutrino charge-currentcapture time and expansion timescale are similar (∼ 1 s)
Neutrinos speed-up matter flowν̄e + p→ e+ + nn + 64Ge→ 64Ga + p64Ga + p→ 65Ge . . .
These reactions constitute the νp-processC. Fröhlich, et al., PRL 96, 142502 (2006)
Supernova model courtesy from H.-Th. Janka
60 70 80 90 100 110 120Mass number A
10−1
100
101
102
Mi/(
Mej
Xi,⊙
)
Cu
Zn GaGe
As
Se
Br
Kr
Rb
Sr
Y
ZrNb
Mo
Ru
Rh
Pd
Cd
Sensitivity to masses and astrophysicalconditions.
Introduction Nucleosynthesis in supernova neutrino ejecta Accretion disks in collapsar models r-process Summary
Masses measured at SHIPTRAP and JYLFTRAP
���� �� �� �� �� �� � � �� �� �� �� �� �� �� � �
��
���
��
��
��
��
��
��
��
��
�
��
��
� �
��
�
��
�
��
�
��
�
��
�
��
�
��
�
�
�
�� �
��
�
�
�
�
�
��
�
��
�
��
�
��
�
��
�
��
�
��
�
�
����
��
��
��
��
��
��
�
��
�
��
��
��
��
��
��
��
��
��
��
��
��
��
��
����
��
��
��
��
��
��
��
��
�
��
�
��
��
��
��
��
��
��
��
��
��
��
��
����
��
��
��
��
��
��
��
��
��
��
��
��
��
��
�
��
�
��
��
��
��
��
��
��
��
��
��
����
�
��
�
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
�
��
�
��
��
��
��
��
��
��
��
����
��
��
��
��
�
��
�
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
�
��
�
��
��
��
��
��
��
����
��
��
��
��
��
��
��
��
�
��
�
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
�
��
�
��
��
��
��
����
��
��
��
��
��
��
��
��
��
��
�
��
�
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
�
��
�
��
��
���
��
��
��
��
��
��
��
��
��
��
��
��
��
��
�
��
�
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
���
�
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
�
��
�
��
��
��
��
��
��
��
��
��
��
��
��
��
��
����
��
��
�
��
�
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
�
��
�
��
��
��
��
��
��
��
��
��
��
���
��
�
��
�
��
�
�
�
�
�
��
�
��
�
��
�
��
�
��
�
��
�
��
�
��
�
�
�
�
�
��
�
��
�
��
�� �
��
�
��
�
��
�
��
�
��
�
��
�
��
�
��
�
�
�
�
�
��
�
��
�
��
�
��
�
��
�
��
�
��
�
��
�
�
�
�
����
��
��
��
��
��
��
��
��
��
��
��
��
��
��
�
��
�
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
��
�
��
��
��
��
�
��
�
��
��
�
��
��
�����
��
�� ��
�� ��
��
��
������
�������
��
�
�
�
�
�
�
�
��
�
�
�
�
�
�
�
�
��������
������
ν� ������������
C. Weber et al, Phys. Rev. C 78, 054310 (2008)
Introduction Nucleosynthesis in supernova neutrino ejecta Accretion disks in collapsar models r-process Summary
Influence new masses
10−1
100
101
102
Mi/(
Mej
Xi,⊙
)
AWExpt.
60 70 80 90 100 110 120Mass number
0.1
1
Rat
io
Zn
GaGe
As
Se
Br
Kr
Rb
Sr
Y
Zr
Nb
MoRu
Pd
Cd
Se Kr SrMo
Ru
Pd
New set of reaction rates using newexperimental masses (T. Rauscher).
New experimentar values close toAudi-Wapstra systematics. Littlechanges in abundances.
No spectroscopic information isknown for these nuclei. Sensitivitystudies of the important reactionrates are necessary. However,νp-process seems to occur under(p, γ)� (γ, p) equilibrium.
Having the nuclear physics undercontrol allows to explore theastrophysical uncertainties. Theνp-process can be used constrainthe evolution of the ejected matter.
Introduction Nucleosynthesis in supernova neutrino ejecta Accretion disks in collapsar models r-process Summary
Sensitivity to temperature evolution
The νp-process nucleosynthesis is rather sensitive to the temperatureevolution of the ejected matter. In particular, to the interaction with thereverse shock.
0 0.5 1 1.5Time (s)
0
1
2
3
4
5
6
7
8
9
10
Tem
pera
ture
(G
K)
60 70 80 90 100 110 120Mass number A
10−2
10−1
100
101
102
103
Mi/(
Mej
Xi,⊙
)
Trs = 2 GKTrs = 3 GKTrs = 1 GKno rs
Cu
Zn
GaGe
As
Se
Br
Kr
Rb
Sr
Y
ZrNb
Mo
Ru
Rh
Pd
Cd
(A. Arcones & GMP, in preparation)
Introduction Nucleosynthesis in supernova neutrino ejecta Accretion disks in collapsar models r-process Summary
Collective neutrino transitions
Nucleosynthesis may be sensitive to collective neutrino transitions.Changes are sensitive to the assumed spectra of neutrinos.
Fogli, et al, PRD 78, 097301 (2008)
E (MeV)0 10 20 30 40 50
Flu
x (a
.u.)
0.0
0.2
0.4
0.6
0.8
1.0
eν
xν
E (MeV)0 10 20 30 40 50
eν
xν
Initial neutrino and antineutrino fluxes
E (MeV)0 10 20 30 40 50
Flu
x (a
.u.)
0.0
0.2
0.4
0.6
0.8
1.0
xν
eν
> = 24 MeVx< E
> = 10 MeVe< E
E (MeV)0 10 20 30 40 50
xν
eν
> = 24 MeVxE<
> = 15 MeVeE<
Inverted hierarchy.
Dasgupta et al, PRL 103, 051105 (2009)Antineutrinos
IH
Neutrinos
IH
0 10 20 30 40
Energy [MeV]
NH
0 10 20 30 40 50
Energy [MeV]
NH
Collective neutrino transformation mayprovide a way to convert proton-rich ejectainto neutron-rich ejecta.
Introduction Nucleosynthesis in supernova neutrino ejecta Accretion disks in collapsar models r-process Summary
The νp-process in black hole accretions disks
L. Kizivat, GMP, K. Langanke, R. Surman, G. McLaughlin
accretion disk
outflow outflowejecta
ejecta
BH
ne e
,n
ne e
,n
ne e
,nne e
,n
ne e
,n
GRB jet
PNS 40 45 50 55 60 65 70 75 80 85 90 95 100Mass Number A
100
101
102
103
104
105
Yi/Y
i,⊙
Mdot = 1 M⊙/sβ = 2.5s = 30
40 45 50 55 60 65 70 75 80 85 90 95 100Mass Number A
100
101
102
103
104
105
Yi/Y
i,⊙
Mdot = 1 M⊙/sβ = 0.8s = 30
40 45 50 55 60 65 70 75 80 85 90 95 100Mass Number A
100
101
102
103
104
105
Yi/Y
i,⊙
Mdot = 1 M⊙/sβ = 2.5s = 15
40 45 50 55 60 65 70 75 80 85 90 95 100Mass Number A
100
101
102
103
104
105
Yi/Y
i,⊙
Mdot = 0.1 M⊙/sβ = 2.5s = 30
Introduction Nucleosynthesis in supernova neutrino ejecta Accretion disks in collapsar models r-process Summary
r-process and metal-poor stars
Cowan & Sneden, Nature 440, 1151 (2006)
Atomic number
Nb
YGe
Ga
Sr
Zr
Mo
Ru
RhAg
PdCd
SnBa
Nd
Ce
La
Pr
Eu
Tb
SmGd
DyEr
Yb
OsPt
Ir
Au
Pb
Th
U
Hf
Ho
TmLu
CS22892–052 detections1
0
–1
–2
1
0
30
a
b
40 50 60 70 80 90–1
CS22892–052 upper limits
Normalized at Eu
Observed minus Solar System r-process only
log
ε(X
)�
lo
g ε
(X)
Solar System r-process onlySolar System s-process only
Several stars show robust r-process for Z > 56.
Nucleosynthesis Signatures offew (single?) events.
Abundances Z > 56 consistentwith solar r-processabundance. Z < 56 areunderproduced with respectsolar abundances.
At least two differentastrophysical sites arenecessary to explain solarr-process abundances.
What is the origin of the robust r-process?Can fission cycling provide a robust r-process?
Introduction Nucleosynthesis in supernova neutrino ejecta Accretion disks in collapsar models r-process Summary
Robust r-process: fission cycling
60 90 120 150 180 210 240A
10−9
10−8
10−7
10−6
10−5
10−4
10−3
10−2
Y
n/seed = 141n/seed = 186n/seed = 295n/seed = 403
FRDM
60 90 120 150 180 210 240A
10−9
10−8
10−7
10−6
10−5
10−4
10−3
10−2
Y
n/seed = 141n/seed = 186n/seed = 295n/seed = 403
ETFSI−Q
Depending on the mass modelused fission cycling can provide arobust abundance pattern.
FRDM: ‘robust’ abundancepattern as observed in metal-poorstars.
ETFSI-Q: abundance patternstrongly depends on theastrophysical conditions.
Introduction Nucleosynthesis in supernova neutrino ejecta Accretion disks in collapsar models r-process Summary
Summary
Nucleosynthesis in supernova ejecta is very sensitive to the emittedneutrino fluxes and spectra and possibly to oscillation phenomena.
Supernova simulations show the existence of proton-rich ejectathat constitute the site of a novel nucleosynthesis process: Theνp-process.
The νp-process may explain the solar abundances of light p-nuclei(92,94Mo, 96,98Ru).
r-process nucleosynthesis requires the knowledge of the propertiesof extremely neutron-rich nuclei. Future experimental facilities(FAIR) will reduce the nuclear uncertainties and greatly constrainthe astrophysical models.