Introduction Model Simulations Results
Simulations of X-ray Bursts and Superbursts
J. Reichert, R. Cabezon, S.Fehlmann, F.-K. ThielemannUniversity of Basel, Switzerland
30.9.2016
Brainstorm and Fun, Basel, 29.9.-1.10.2016
J. Reichert, R. Cabezon, S.Fehlmann, F.-K. Thielemann University of Basel, SwitzerlandSimulations of X-ray Bursts and Superbursts 30.9.2016 1 / 17
Introduction Model Simulations Results
J. Reichert, R. Cabezon, S.Fehlmann, F.-K. Thielemann University of Basel, SwitzerlandSimulations of X-ray Bursts and Superbursts 30.9.2016 2 / 17
Introduction Model Simulations Results
X-Ray Bursts and Superbursts
X-Ray Bursts
Energy release: 1039 [ergs]
Luminosity : 1038 [ergs/s]
Burst time : sec-min
Burst recurrence: hours-days
Superbursts
Energy release: 1042 [ergs]
Luminosity : 1038 [ergs/s]
Burst time : hours-days
Burst recurrence: years
J. Reichert, R. Cabezon, S.Fehlmann, F.-K. Thielemann University of Basel, SwitzerlandSimulations of X-ray Bursts and Superbursts 30.9.2016 3 / 17
Introduction Model Simulations Results
1
108
1012
1015
1019
104100100100.01
Column density[g cm-2]
Depth[m]
X-ray burst
Superburst
Accre
tion
X-Ray Bursts
Unstable hydrogen and heliumburning
Superbursts
Unstable carbon burning
X12C & 0.1 (Cumming et al., 2006; Hashimoto et al., 2014)
J. Reichert, R. Cabezon, S.Fehlmann, F.-K. Thielemann University of Basel, SwitzerlandSimulations of X-ray Bursts and Superbursts 30.9.2016 4 / 17
Introduction Model Simulations Results
1D-Model
Code J.Fisker, S.Fehlmann, M. Liebendorfer
General relativistic hydrodynamics: AGILE (M. Liebendorfer, 2002)
Nuclear Network (W. R. Hix & F.-K. Thielemann, 1999)
Convection
Heat transport: Conduction and Radiation
J. Reichert, R. Cabezon, S.Fehlmann, F.-K. Thielemann University of Basel, SwitzerlandSimulations of X-ray Bursts and Superbursts 30.9.2016 5 / 17
Introduction Model Simulations Results
Initial Model
The computationaldomain:m = 4.8 · 1024gr ≈ 85m
Adaptive grid with218 zones
Initial Parameters
Netron star: r = 11.2km, m = 1.41M�
K. Nomoto’s EOS
Accreted solar composition with constant accretion rate
Fixed heat source Qheat as an inner boundary condition
J. Reichert, R. Cabezon, S.Fehlmann, F.-K. Thielemann University of Basel, SwitzerlandSimulations of X-ray Bursts and Superbursts 30.9.2016 6 / 17
Introduction Model Simulations Results
Parameter Sets with solar accretion composition(Anders&Grevesse solar abundances taken from Arnett92)I: varying crustal heatingfrom 0.3− 1.1 MeV per nucleon in steps of 0.1 MeV/nuc
accretion rate
0.5 · 1017 g s−1
1 · 1017 g s−1
1.5 · 1017 g s−1
composition
XH = 0.706XHe = 0.275Xrest = 0.019
II: varying accretion ratefrom 0.1− 1.5 · 1017 g s−1 in steps of 0.1 · 1017 g s−1
crustal heating
0.4 Mev nuc−1
0.8 Mev nuc−1
1.2 Mev nuc−1
composition
XH = 0.706XHe = 0.275Xrest = 0.019
solar composition: (Anders&Grevesse solar abundances taken from Arnett92)
J. Reichert, R. Cabezon, S.Fehlmann, F.-K. Thielemann University of Basel, SwitzerlandSimulations of X-ray Bursts and Superbursts 30.9.2016 7 / 17
Introduction Model Simulations Results
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
Qh
ea
t [M
eV
/nuc]
Accretion rate [1017
g/s]
burning regimes
Stable burningIrregular burstsRegular bursts
J. Reichert, R. Cabezon, S.Fehlmann, F.-K. Thielemann University of Basel, SwitzerlandSimulations of X-ray Bursts and Superbursts 30.9.2016 8 / 17
Introduction Model Simulations Results
Stable burning regime
solar abundances with 0.4 MeV/nuc crustal heating
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0 500000 1e+06 1.5e+06 2e+06 2.5e+06 3e+06
lum
ino
sity [
10
37e
rg/s
]
time [s]
solar composition, accretion rate = 0.2*1017
g/s, Qheat=0.4 Mev/nuc
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
5 6 7 8 9 10 11 12
X [
]Log Column Density [g/cm
2]
solar composition, accretion rate = 0.2*1017
g/s, Qheat=0.4 Mev/nuc
12C
4HeH
X=0.1
”New regime of stable nuclear burning”(L. Keek and A. Heger, 2015)
J. Reichert, R. Cabezon, S.Fehlmann, F.-K. Thielemann University of Basel, SwitzerlandSimulations of X-ray Bursts and Superbursts 30.9.2016 9 / 17
Introduction Model Simulations Results
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
Qh
ea
t [M
eV
/nuc]
Accretion rate [1017
g/s]
burning regimes
Stable burningIrregular burstsRegular bursts
J. Reichert, R. Cabezon, S.Fehlmann, F.-K. Thielemann University of Basel, SwitzerlandSimulations of X-ray Bursts and Superbursts 30.9.2016 10 / 17
Introduction Model Simulations Results
Irregular bursts regime
solar abundances with 1 · 1017 g s−1 accretion rate
0
1
2
3
4
5
6
7
8
0 2e+06 4e+06 6e+06 8e+06 1e+07 1.2e+07 1.4e+07
lum
ino
sity [
10
37e
rg/s
]
time [s]
solar composition, accretion rate = 1017
g/s, Qheat=1.5 Mev/nuc
irregular burst → stable burning
J. Reichert, R. Cabezon, S.Fehlmann, F.-K. Thielemann University of Basel, SwitzerlandSimulations of X-ray Bursts and Superbursts 30.9.2016 11 / 17
Introduction Model Simulations Results
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
5 6 7 8 9 10 11 12
X [ ]
Log Column Density [g/cm2]
solar composition, accretion rate =1017
g/s, Qheat=1.5 Mev/nuc
12C
4HeH
X=0.1
J. Reichert, R. Cabezon, S.Fehlmann, F.-K. Thielemann University of Basel, SwitzerlandSimulations of X-ray Bursts and Superbursts 30.9.2016 12 / 17
Introduction Model Simulations Results
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
Qh
ea
t [M
eV
/nuc]
Accretion rate [1017
g/s]
burning regimes
Stable burningIrregular burstsRegular bursts
J. Reichert, R. Cabezon, S.Fehlmann, F.-K. Thielemann University of Basel, SwitzerlandSimulations of X-ray Bursts and Superbursts 30.9.2016 13 / 17
Introduction Model Simulations Results
Regular bursts
solar abundances with 0.8 MeV/nuc crustal heating
0
1
2
3
4
5
6
7
8
0 200000 400000 600000 800000 1e+06
lum
ino
sity [
10
37e
rg/s
]
time [s]
solar composition, accretion rate = 0.8*1017
g/s, Qheat=0.8 Mev/nuc
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
5 6 7 8 9 10 11 12X
[ ]
Log Column Density [g/cm2]
solar composition, accretion rate = 0.8*1017
g/s, Qheat=0.8 Mev/nuc
12C
4HeH
X=0.1
J. Reichert, R. Cabezon, S.Fehlmann, F.-K. Thielemann University of Basel, SwitzerlandSimulations of X-ray Bursts and Superbursts 30.9.2016 14 / 17
Introduction Model Simulations Results
the orange region corresponds to the parameter sets which produceX(12C) > 0.1
J. Reichert, R. Cabezon, S.Fehlmann, F.-K. Thielemann University of Basel, SwitzerlandSimulations of X-ray Bursts and Superbursts 30.9.2016 15 / 17
Introduction Model Simulations Results
the orange region corresponds to the parameter sets which produceX(12C) > 0.1
J. Reichert, R. Cabezon, S.Fehlmann, F.-K. Thielemann University of Basel, SwitzerlandSimulations of X-ray Bursts and Superbursts 30.9.2016 16 / 17
Introduction Model Simulations Results
Thank You for your attention!
J. Reichert, R. Cabezon, S.Fehlmann, F.-K. Thielemann University of Basel, SwitzerlandSimulations of X-ray Bursts and Superbursts 30.9.2016 17 / 17
