r-process nucleosynthesis
in AD-BH outflows
Rebecca Surman
Union CollegeWorkshop on SNe and GRBs
Yukawa Institute, Kyoto, Japan
12 November 2013

R Surman
Union CollegeGRBs Kyoto 2013

plot courtesy A. Arcones

solar system abundances

R Surman
Union CollegeGRBs Kyoto 2013

solar system abundances

Arnould, Goriely (2003)

R Surman
Union CollegeGRBs Kyoto 2013

r-process nucleosynthesis
abundances fromAnders and Grevesse (1988)

N=50
N=82
N=126
rare earth peakβ(n, γ )(γ ,n)€€

R Surman
Union CollegeGRBs Kyoto 2013

r-process site: mergers?
neutron star-neutron star or black
hole-neutron star mergers

Korobkin et al(2012)

Goriely et al (2012)

e.g., Lattimer & Schramm (1974, 1976), Meyer (1989), Frieburghaus et al (1999), Goriely et al(2005), Rosswog (2005), Wanajo & Ishimaru (2006), Oechslin et al (2007), Metzger et al (2010),
Roberts et al (2011), Goriely et al (2012), Korobkin et al (2012), Tanaka & Hotokezaka (2013), S.
Wanajo talkR Surman
Union College
GRBs Kyoto 2013

r-process site: mergers?

Argast et al (2004)

R Surman
Union College
GRBs Kyoto 2013

r-process site: supernovae?
supernova neutrino-driven windPNS

νlate-time ν fluxes from Keil et al (2003)

p + ν e ↔ n + e+n + ν e ↔ p + e−e.g., Meyer et al (1992), Woosley et al (1994), Takahashi et al (1994), Witti et al (1994), Fuller &Meyer (1995), McLaughlin et al (1996), Meyer et al (1998), Qian & Woosley (1996), Hoffman et al(1997), Cardall & Fuller (1997), Otsuki et al (2000), Thompson et al (2001), Terasawa et al (2002),
Liebendorfer et al (2005), Wanajo (2006), Arcones€
et al (2007), Huedepohl et al (2010), Fischer et al(2010), Roberts & Reddy (2012), etc., etc.

R Surman
Union CollegeGRBs Kyoto 2013

primary heavy element nucleosynthesis

R Surman
Union CollegeGRBs Kyoto 2013

neutrinos and primary nucleosynthesisp + ν e ↔ n + e+n + ν e ↔ p + e−

R Surman
Union CollegeGRBs Kyoto 2013

neutrinos and primary nucleosynthesisp + ν e ↔ n + e+n + ν e ↔ p + e−

R Surman
Union CollegeGRBs Kyoto 2013

neutrinos and primary nucleosynthesisp + ν e ↔ n + e+n + ν e ↔ p + e−

R Surman
Union CollegeGRBs Kyoto 2013

r-process astrophysical site: status

Compact object mergers have plenty of neutrons, but do not evolveon short enough timescales to explain the halo star data
Core-collapse supernovae evolve on the correct timescale toexplain the halo star data, but may not produce enough neutrons(but see talk by N. Nishimura for an alternate SNe site...)R Surman
Union CollegeGRBs Kyoto 2013

black hole accretion disks (AD-BHs)

jet (?)

outflowνaccretiondisk

R Surman
Union CollegeGRBs Kyoto 2013

black hole accretion disks (AD-BHs)

jet (?)

GRB jet/explosive nucleosynthesis

outflowνaccretion
diske.g., Beloborodov (2003), Nagataki et al(2003), Nagataki et al (2006), Fryer et al(2006), Fujimoto et al (2007), Fujimoto et al(2008), Tominaga (2009), Maeda & Tominaga(2009), Nomoto et al (2010), Horiuchi et al(2012), Shibata & Tominaga (2012), Nakamuraet al (2013)

R Surman
Union CollegeGRBs Kyoto 2013

black hole accretion disks (AD-BHs)

jet (?)

outflowνaccretion
disk

AD-BH outflow nucleosynthesise.g., Pruet, Thompson, & Hoffman (2004),
Surman & McLaughlin (2004), Arai et al(2004), Fujimoto et al (2004), Surman,McLaughlin, & Hix (2006), Barzilay &Levinson (2008), Metzger, Thompson, &Quataert (2008), Kizivat et al (2010), Wanajo& Janka (2012)

R Surman
Union CollegeGRBs Kyoto 2013

black hole accretion disk neutrino emission

positron captures dominate
in merger disks, sofν > fνeen + e+ ↔ p + ν e
p + e− ↔ n + ν eelectron captures dominate
in collapsar disks, sofν > fνDisk models from Chen and Beloborodov (2008),
neutrino calculation from Surman and McLaughlinee

R Surman
Union CollegeGRBs Kyoto 2013nucleosynthesis from a merger black hole accretion disk

Surman, McLaughlin, Ruffert, Janka, Hix (2008)

R Surman
Union CollegeGRBs Kyoto 2013

nucleosynthesis from a merger black hole accretion disk

Assume an adiabatic wind with

# R0 &v = v∞ %1− ($r 'β

low s/k,fast accelerationhigh s/k,
slower acceleration

Surman, McLaughlin, Ruffert, Janka, Hix(2008)

R Surman
Union CollegeGRBs Kyoto 2013

nucleosynthesis from a merger black hole accretion disk
Wanajo & Janka

10-2
10-3

abundance

102

SS-4

10-5
10-6

METZGER, THOMPSON, & QUATAERT

10-7
10-8

50

100

10-2abundance

Wanajo, Janka (2012)

solar r-process abundancecase 1 all D < 5 R D < 3 R

10-3

10-4150
mass number

200

250

solar r-process abundancecase 2 all D < 5 RS D < 3 RS

10-5
10-6
10-7
10-8
50

Metzger et al (2008)
100150mass number

200

250

Figure 20. Time-integrated nucleosynthetic abundances for the entire torus forcase 1 (top panel) and case 2 (bottom panel). The calculated abundances for caseVolR Surman
Union CollegeGRBs Kyoto 2013

nucleosynthesis from a merger black hole accretion disk

Surman, McLaughlin, Ruffert, Janka, Hix (2008)

R Surman
Union CollegeGRBs Kyoto 2013

general relativistic effects on the neutrino spectra
no GR
redshift, bending+ rotation+ Kerr metric forredshift
Caballero, McLaughlin, Surman(2011)

low s/k,fast acceleration

R Surman
Union CollegeGRBs Kyoto 2013

general relativistic effects on the neutrino spectra
no GR
redshift, bending+ rotation+ Kerr metric forredshift
Caballero, McLaughlin, Surman(2011)

high s/k,slower acceleration

R Surman
Union CollegeGRBs Kyoto 2013nucleosynthesis from a time-dependent merger diskt = 20 ms

Disk model from Just and Janka
Neutrino decoupling surface
calculation by L. Caballero
t = 60 ms

R Surman
Union CollegeGRBs Kyoto 2013

nucleosynthesis from a time-dependent merger disk

neutrino-only equilibrium electron fractions

t = 20 ms
t = 60 ms

Surman, Caballero, McLaughlin, Just, Janka, submitted (2013)

R Surman
Union CollegeGRBs Kyoto 2013

nucleosynthesis from a time-dependent merger disk: 56Ni

Surman, Caballero, McLaughlin, Just, Janka, submitted (2013)

R Surman
Union CollegeGRBs Kyoto 2013

r-process in the oldest stars?

Cowan et al (2011)

R Surman
Union CollegeGRBs Kyoto 2013

nucleosynthesis from lower accretion rate/collapsar disks: 56Ni

Surman, McLaughlin,
Sabbatino (2011)

3.1.2.

ṁ < 0.2

The outflows from AD-BHs w
fer slightly from the above pic
lower mass accretion rates havetemperatures and densities. Th
effect of this for disks with 0.1 ≤the outflows have lower starting
densities. This means the weakessarily fast enough for the ele
reequilibrate in the outflow pri
assembly, and so the neutron ric
is retained to higher entropies.

R Surman
Union CollegeGRBs Kyoto 2013

collapsar disk with trapped neutrinos and antineutrinos

Neutrino emission similar to a protoneutron star (PNS) in a typical corecollapse event, except:_

 primarily νe and νe (vs. all flavors in a PNS) emission surfaces not spherical_ νe emission surface much larger than that for νe
As a result, antineutrino emission can dominate over neutrino emission closeto the disk, but neutrino emission can dominate farther out

R SurmanUnion CollegeGRBs Kyoto 2013

neutrino oscillations

Two flavor mixing in matter with a high neutrino flux:'*δm 2
δm 2abcos(2θ )Vν +sin(2θ ) ,)Ve + Vν −d4E4Eic ψν = ),ψν22δmδmdr) Vb +sin(2θ )−Ve − Vνa +cos(2θ ),ν(+4E4E€θ
mixing angle
2δm mass difference squaredE
neutrino energy
Ve effective potential due to matterVν neutrino self interaction potentials

R Surman
Union CollegeGRBs Kyoto 2013

neutrino oscillationsTwo flavor mixing in matter with a high neutrino flux:xxxx'*δm 2
δm 2abcos(2θ )Vν +sin(2θ ) ,)Ve + Vν −d4E4Eic ψν = ),ψν22δmδmdr) Vb +sin(2θ )−Ve − Vνa +cos(2θ ),ν(+4E4E€θ
mixing angle
2δm mass difference squared
Eneutrino energy
Ve effective potential due to matterVν neutrino self interaction potentials

δm2cos(2θ )MSW flavor transition: Ve ≈4E

R SurmanUnion CollegeGRBs Kyoto 2013neutrino oscillations

Two flavor mixing in matter with a high neutrino flux:x'*δm 2
δm 2abcos(2θ )Vν +sin(2θ ) ,)Ve + Vν −d4E4Eic ψν = ),ψν
22δmδmdr) Vb +sin(2θ )−Ve − Vνa +cos(2θ ),
ν(+4E
4E

€x

θmixing angle2
δm mass difference squaredEneutrino energy
Ve effective potential due to matterVν neutrino self interaction potentials

Collective flavor transformation:€δm 2Vν ≈cos(2θ )4E

R SurmanUnion CollegeGRBs Kyoto 2013

black hole accretion disk neutrino oscillations

Malkus, McLaughlin, Kneller, Surman(2012)

neutrino selfinteraction
mattervacuum terms

22'*δmδ
mabcos(2θ )Vν +sin(2θ ) ,)Ve + Vν −d4E4Eic ψν = ),ψν22δmdra) V b + δm sin(2θ )−V−
V+cos(2θ ),νeν(+4E4E

R Surman
Union CollegeGRBs Kyoto 2013

AD-BH neutrino oscillations: consequences for nucleosynthesis

no oscillations
single angle νoscillationcalculationnα	Malkus, McLaughlin, Kneller,Surman (2012)

R Surman
Union CollegeGRBs Kyoto 2013

AD-BH neutrino oscillations: consequences for nucleosynthesis

no oscillations
single angle νoscillation
calculation

Malkus, McLaughlin, Kneller, Surman (2012)

R Surman
Union CollegeGRBs Kyoto 2013

summary (I)Neutrinos play a key role in heavy element synthesis in GRB black holeaccretion disk outflows. Neutrinos can:• set the initial neutron-to-proton ratio• determine free nucleon availability for capture after seed formation
A careful treatment of the neutrino physics – including oscillations andgeneral relativistic effects – is therefore essential to accurately predict
nucleosynthetic outcomes in this environment

R Surman
Union CollegeGRBs Kyoto 2013

r-process astrophysical site: a new approach?

With the next generation of radioactive beam facilities + theoretical efforts
to develop improved models, we will know the nuclear physics propertiesof nuclei populated in the late stages of the r-process
With the current and planned stellar surveys + follow-up spectroscopy, wewill know the r-process abundance pattern (and all of its variations) inunprecedented detail
we can use these details to get at the hydrodynamic conditions thatmust have existed during the late stage of the r-process

R Surman
Union CollegeGRBs Kyoto 2013

example: the rare earth peak
•

N=50
N=82
N=126
rare earth peak

Surman, Engel, Bennett, Meyer (1997)

Forms at the late stages of the rprocess, during freezeout from(n,γ)-(γ,n) equilibrium

R Surman
Union CollegeGRBs Kyoto 2013

example: the rare earth peak•Forms at the late stages of the rprocess, during freezeout from(n,γ)-(γ,n) equilibrium•The formation mechanism issensitive to both the astrophysicalconditions of the late phase of ther-process and the nuclear physics
of the nuclei populated at thistime

N=50
N=82
N=126
rare earth peak

Surman, Engel, Bennett, Meyer (1997)

R Surman
Union CollegeGRBs Kyoto 2013

rare earth peak formation: nuclear data uncertainties

FRDM

Mumpower, McLaughlin, Surman, PRC (2012)

HFB-21

R Surman
Union CollegeGRBs Kyoto 2013

experimental prospects+ RIKEN + ARIEL + FAIR

FRIB (figure from G. Bollen)

CARIBU (figure from F. Montes)

R Surman
Union CollegeGRBs Kyoto 2013using the rare earth peak to constrain r-process conditions

Parameterized wind based on Meyer(2002):& Δ )n−3t / τρ(t) = ρ1e+ ρ2(+'Δ + t *Mumpower, McLaughlin, Surman, ApJ(2012)€with τ=80 ms, Ye=0.3, FRDM masses
Vary 50<s/k<400, 0<n<10R Surman
Union CollegeGRBs Kyoto 2013using the rare earth peak to constrain r-process conditions

match with rare earth region
match with ratio of the A~195 main peak torare earth peakminimal late time neutron capture

Mumpower, McLaughlin, Surman, ApJ(2012)

R Surman
Union CollegeGRBs Kyoto 2013

summary (II)The rare earth peak offers unique insight into the nuclear physics and theastrophysics of the r-process. Its formation seems to require:a deformation maximum in the rare earth regionthe ‘right amount’ of neutron capture at late times in the r-process

Once the nuclear physics uncertainties are clarified by experiments at the next
generation of radioactive beam facilities, the rare earth peak will become aneven more powerful probe of the r-process astrophysical environment.