Neutrinos and Explosive...

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


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.


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.


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?


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 –


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)


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)


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


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)


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)


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


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


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.


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


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


The νp process






As65

64Ge

64Ga

n,p( )

65Ge

66As

(p, )γ

(p, )γ

~ 1 s


The νp process






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.


Masses measured at SHIPTRAP and JYLFTRAP

��

��

��

��

��

��

��

��

��

��

��

�

��

��

� �

��

�

��

�

��

�

��

�

��

�

��

�

��

�

�

�

��

��

�

�

�

�

�

��

�

��

�

��

�

��

�

��

�

��

�

��

�

�

��

��

��

��

��

��

��

�

��

�

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

�

��

�

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

�

��

�

��

��

��

��

��

��

��

��

��

��

��

�

��

�

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

�

��

�

��

��

��

��

��

��

��

��

��

��

��

��

��

�

��

�

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

�

��

�

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

�

��

�

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

�

��

�

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

�

��

�

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

�

��

�

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

�

��

�

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

�

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

�

��

�

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

�

��

�

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

�

��

�

��

��

��

��

��

��

��

��

��

��

��

��

�

��

�

��

�

�

�

�

�

��

�

��

�

��

�

��

�

��

�

��

�

��

�

��

�

�

�

�

�

��

�

��

�

��

��

��

�

��

�

��

�

��

�

��

�

��

�

��

�

��

�

�

�

�

�

��

�

��

�

��

�

��

�

��

�

��

�

��

�

��

�

�

�

�

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

�

��

�

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

�

��

��

��

��

�

��

�

��

��

�

��

��

��

��

��

��

��

��

��

��

��

�

�

�

�

�

�

�

��

�

�

�

�

�

�

�

�

��

��

ν� ��

C. Weber et al, Phys. Rev. C 78, 054310 (2008)


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.


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)


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.


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


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?


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.


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.

Neutrinos and Explosive...

Documents

Transcript of Neutrinos and Explosive...