Post on 25-Sep-2020
ν-driven wind in the Aftermath ofNeutron Star Merger
Albino Peregoin collaboration with A. Arcones, R. Cabezon, R. Kappeli, M. Liebendorfer, S. Rosswog
albino.perego@physik.tu-darmstadt.de
Technische Universitat Darmstadt
Institute for Nuclear Physics, Theory
GRBs in Kyoto Conference, Kyoto, 11-15 November 2013ν-driven wind in the aftermath of NS merger, GRBs in Kyoto Conference - 11-15 November 2013 – p. 1/15
Outline of the presentation
Introduction: ejected matter from binary neutron starmerger
The modelinitial conditionsASL neutrino treatment
Preliminary results
Conclusion and outlook
ν-driven wind in the aftermath of NS merger, GRBs in Kyoto Conference - 11-15 November 2013 – p. 2/15
Matter ejecta from BNS mergers
BNS mergers are among the most promising candidates toexplain short gamma-ray bursts (GRBs).
observations: good compatibility with observed rates,redshifts and host galaxies
modelling: intense energy deposition in a relativelybaryon-free region as driving mechanism, due to matteraccretion on a stellar compact object (SMNS or BH)
Possible ejecta from BNS mergers
dynamical ejecta (e.g. Rosswog 13, Bauswein et al 13, Hotokezaka et al 13)
delayed disc evaporation (e.g. Fernandez & Metzger 2013)
neutrino-driven ejecta (e.g. Dessart et al. 2009)
ν-driven wind in the aftermath of NS merger, GRBs in Kyoto Conference - 11-15 November 2013 – p. 3/15
The model
Goal: extensive study the aftermath of BNSM
ν emission
disk dynamics and ν-driven wind formation
nucleosynthesis in the wind
baryonic pollution and GRB engine
Model ingredients:
data from Newtonian SPH BNS merger simulations(Price & Rosswog (2006))
FISH 3D (M)HD Cartesian code (Käppeli et al. (2011))
TM1 nuclear EoS (Hempel et al. (2012))
ν treatment: Advanced Spectral Leakage (ASL) scheme(Perego et al., in preparation)
ν-driven wind in the aftermath of NS merger, GRBs in Kyoto Conference - 11-15 November 2013 – p. 4/15
Initial conditions
3D SPH data mapped on 3D FISH grid
1 km resolution: SMNS treated as stationary object
data relaxation: ∆t ≈ 10ms, hydro + ν emission
Matter density (2D avg) Temperature (2D avg) Electron fraction (2D avg)
ν-driven wind in the aftermath of NS merger, GRBs in Kyoto Conference - 11-15 November 2013 – p. 5/15
Relevant timescales
disc lifetime:
tvisc ∼ α−1
(
H
R
)−2
Ω−
K1 ∼ 0.31 s( α
0.05
)−1(
H/R
1/3
)−2 ( R
100 km
)3/2 ( M
2.5M⊙
)−1/2
α: viscosity coefficientH: disc typical heightR: radial position in the discΩK : Keplerian angular velocity
M : SMNS mass
ν-driven wind in the aftermath of NS merger, GRBs in Kyoto Conference - 11-15 November 2013 – p. 6/15
Relevant timescales
disc lifetime: tvisc ∼ 0.31 s(
α0.05
)−1(
H/R1/3
)−2 (R
100 km
)3/2 (M
2.5M⊙
)−1/2
disc dynamical time:
tdyn disc ∼2π
ΩK∼∼ 0.0109 s
(
R
100 km
)3/2 ( M
2.5M⊙
)−1/2
ν-driven wind in the aftermath of NS merger, GRBs in Kyoto Conference - 11-15 November 2013 – p. 6/15
Relevant timescales
disc lifetime: tvisc ∼ 0.31 s(
α0.05
)−1(
H/R1/3
)−2 (R
100 km
)3/2 (M
2.5M⊙
)−1/2
disc dynamical time: tdyn disc ∼ 0.0109 s(
R100 km
)3/2 (M
2.5M⊙
)−1/2
disc cooling time:
tcool ∼∆Edisc,t=0∑
ν Lν∼ 0.20 s
(
∆Edisc,t=0
2× 1052erg
)(∑
ν Lν
1053erg/s
)−1
∆Edisc,t=0 = Eint,disc,t=0 + 12Egrav,disc,t=0
Lν : neutrino luminosity
ν-driven wind in the aftermath of NS merger, GRBs in Kyoto Conference - 11-15 November 2013 – p. 6/15
Relevant timescales
disc lifetime: tvisc ∼ 0.31 s(
α0.05
)−1(
H/R1/3
)−2 (R
100 km
)3/2 (M
2.5M⊙
)−1/2
disc dynamical time: tdyn disc ∼ 0.0109 s(
R100 km
)3/2 (M
2.5M⊙
)−1/2
disc cooling time: tcool ∼ 0.20 s(
∆Edisc,t=0
2×1052erg
)( ∑ν Lν
1053erg/s
)−1
wind time:
twind ∼egrav
eheat∼ 0.10 s
(
M
2.5M⊙
)(
R
80 km
)(
Eν
13MeV
)−2(
(Lν)iso,θ≈π/4
4× 1052 erg/s
)−1
egrav = GM /R : specific gravitational energyeheat = Eν χabs nν / ρ : heating specific energy rate(Lν)iso : isotropized neutrino luminosityχabs : neutrino absorptivity
nν : neutrino density
ν-driven wind in the aftermath of NS merger, GRBs in Kyoto Conference - 11-15 November 2013 – p. 6/15
Relevant timescales
disc lifetime: tvisc ∼ 0.31 s(
α0.05
)−1(
H/R1/3
)−2 (R
100 km
)3/2 (M
2.5M⊙
)−1/2
disc dynamical time: tdyn disc ∼ 0.0109 s(
R100 km
)3/2 (M
2.5M⊙
)−1/2
disc cooling time: tcool ∼ 0.20 s(
∆Edisc,t=0
2×1052erg
)( ∑ν Lν
1053erg/s
)−1
wind time: twind ∼ 0.10 s(
M2.5M⊙
)(
R80 km
)(
Eν13MeV
)−2(
(Lν)iso,θ≈π/4
4×1052 erg/s
)−1
tdyn disc < twind < tcool,disc < tvisc
but there is something missing . . .
ν-driven wind in the aftermath of NS merger, GRBs in Kyoto Conference - 11-15 November 2013 – p. 6/15
Relevant timescales
disc lifetime: tvisc ∼ 0.31 s(
α0.05
)−1(
H/R1/3
)−2 (R
100 km
)3/2 (M
2.5M⊙
)−1/2
disc dynamical time: tdyn disc ∼ 0.0109 s(
R100 km
)3/2 (M
2.5M⊙
)−1/2
disc cooling time: tcool ∼ 0.20 s(
∆Edisc,t=0
2×1052erg
)( ∑ν Lν
1053erg/s
)−1
wind time: twind ∼ 0.10 s(
M2.5M⊙
)(
R80 km
)(
Eν13MeV
)−2(
(Lν)iso,θ≈π/4
4×1052 erg/s
)−1
tdyn disc < twind < tcool,disc < tvisc
but there is something missing . . .
SMNS → BH time (e.g. Bauswein’s and Metzger’s talk) :
tBH ∼ 0.01− 10 s
ν-driven wind in the aftermath of NS merger, GRBs in Kyoto Conference - 11-15 November 2013 – p. 6/15
The ASL scheme
based on previous grey leakage schemes(Ruffert et al. 1997, Rosswog & Liebendörfer 2003, Aloy’s talk)
spectral scheme (12 bins, 2− 200 MeV)
3 flavors: νe,νe, νµ,τ (νµ,τ ≡ νµ, ντ , νµ, ντ )
ν reactions: (ν ≡ νe, νµ, ντ , νe, νµ, ντ )
e− + p → n+ νe O,T,P
e+ + n → p+ νe O,T,P
e− + (A,Z) → νe + (A,Z − 1) T,P
N + ν → N + ν O
(A,Z) + ν → (A,Z) + ν O
e+ + e− → ν + ν T,P
N +N → N +N + ν + ν T,P
major roles: O → opacity, T → thermalization, P → production
Bruenn 1985, Mezzacappa & Bruenn 1993, Hannestad & Raffelt 1998
treatment developed and tested in Core CollapseSupernova context
ν-driven wind in the aftermath of NS merger, GRBs in Kyoto Conference - 11-15 November 2013 – p. 7/15
Neutrino treatment
effective scheme: ASL mimics known solutions
cooling part:smooth interpolation between diffusion andproduction (spectral) ratesreproduction of the correct limits: diffusive (τν ≫ 1)and free streaming (τν . 1)(τν neutrino optical depth)
heating part (for τν . 1):effective treatment of diffusion process in the opaqueregionnν (neutrino density) calculated with ray-tracing fromcooling rates, emitted at neutrino surfacesrheat ∝ χab · nν (χab absorptivity)
ν-driven wind in the aftermath of NS merger, GRBs in Kyoto Conference - 11-15 November 2013 – p. 8/15
Neutrino Surfaces
τν = 2/3 ⇒ ν surfaces, for Eν = 4.6, 10.6, 16.2, 24.6, 57.0MeV, at 40 ms
νe νe νµ,τ
τν,scat
τν,eff
ν-driven wind in the aftermath of NS merger, GRBs in Kyoto Conference - 11-15 November 2013 – p. 9/15
Neutrino luminosities
Isotropized ν luminosityemerging from ν-surfaces
0 22.5 45 67.5 90 112.5 135 157.5 1800
10
20
30
40
50
60
70
80
90
Colatitude [deg]
Iso
tro
piz
ed
lu
min
osity [
10
51 e
rg/s
]
ν
e, 0 ms
Anti−νe, 0 ms
νµ,τ
, 0 ms
ν
e, 40 ms
Anti−νe, 40 ms
νµ,τ
, 40 ms
ν rms energyemerging from ν-surfaces
0 20 40 60 80 100 120 140 160 18010
12
14
16
18
20
22
Colatitude [deg]
Ne
utr
ino
rm
s e
ne
rgy [
Me
V]
ν
e, 0 ms
Anti−νe, 0 ms
νµ,τ
, 0 ms
ν
e, 40 ms
Anti−νe, 40 ms
νµ,τ
, 40 ms
θ angular dependence at t = 0ms and t = 40ms
luminosity hierarchy: Lνe > Lνe > Lνµ,τ
mean energy hierarchy: 〈Eνµ,τ 〉 > 〈Eνe〉 > 〈Eνe〉ν-driven wind in the aftermath of NS merger, GRBs in Kyoto Conference - 11-15 November 2013 – p. 10/15
Neutrino net rates
eν @ 35 ms(
Ye)
ν@ 35 ms vν @ 35 ms
ν-driven wind in the aftermath of NS merger, GRBs in Kyoto Conference - 11-15 November 2013 – p. 11/15
Disc dynamics
Movie Ileft: matter densityright: projected velocity
Movie IIleft: electron fractionright: entropy
ν-driven wind in the aftermath of NS merger, GRBs in Kyoto Conference - 11-15 November 2013 – p. 12/15
Wind properties
occurrence diagrams
large variation for Ye: 0.1 . Ye . 0.35
small variation in entropy: 15 . s [kB/bar] . 25
ν-driven wind in the aftermath of NS merger, GRBs in Kyoto Conference - 11-15 November 2013 – p. 13/15
Conclusions & Outlook
FISH + ASL approximate, suitable tool to model theaftermath of BNS merger
obtained neutrino signature compatible with expectedone
relatively quick ν-driven wind development
wind properties:low entropy: 15 . s[kB/baryon] . 25
mildly low Ye: 0.1 . Ye . 0.35
Outlook:
ejecta properties? → nucleosynthesis, macro/kilo-nova
ν − ν annihilation rate and baryonic pollution? → SGRBmechanism
ν-driven wind in the aftermath of NS merger, GRBs in Kyoto Conference - 11-15 November 2013 – p. 14/15
ν-driven wind in the aftermath of NS merger, GRBs in Kyoto Conference - 11-15 November 2013 – p. 15/15