Nucleosynthesis in Type I X-ray Bursts

1
Nucleosynthesis in Type I X-ray Bursts Anuj
Parikh Technische Universität München
From an XRB animation, NASA/Dana Berry
2
Type I X-ray bursts
Discovery Grindlay et al. (1976), Belian et al.
(1976)
3
Type I X-ray bursts
4
Type I X-ray bursts
Fast risetime!
10 seconds
5
Type I X-ray bursts
6
Type I X-ray bursts

• Discovery Grindlay et al. (1976), Belian et al.
  (1976)
• since then, over 80 such bursting systems have
  been observed!
• most frequent type of thermonuclear stellar
  explosion in the Galaxy
• third most energetic (Etot) after SN and
  classical novae

RXTE (NASA)
BeppoSAX (ASI/NIVR)
Type I XRB light curves
1996 2002
1995
Galloway et al. (2006)
7
Type I X-ray bursts

• Discovery Grindlay et al. (1976), Belian et al.
  (1976)
• since then, over 80 such bursting systems have
  been observed!
• most frequent type of thermonuclear stellar
  explosion in the Galaxy
• third most energetic (Etot) after SN and
  classical novae

• Type II XRBs
• NOT thermonuclear!
• light curves no tail, flat-top
• spasmodic accretion onto NS surface (?)
• only 2 known sources

Type I XRB light curves
Type II XRB light curves
INTEGRAL/ M. Tavani
Galloway et al. (2006)
8
Type I X-ray bursts

• Discovery Grindlay et al. (1976), Belian et al.
  (1976)
• since then, over 80 such bursting systems have
  been observed!
• most frequent type of thermonuclear stellar
  explosion in the Galaxy
• third most energetic (Etot) after SN and
  classical novae

Early models Woosley and Taam (1976), Maraschi
and Cavaliere (1977), Fujimoto et al. (1981)
9
Type I X-ray bursts

• Discovery Grindlay et al. (1976), Belian et al.
  (1976)
• since then, over 80 such bursting systems have
  been observed!
• most frequent type of thermonuclear stellar
  explosion in the Galaxy
• third most energetic (Etot) after SN and
  classical novae

• Early models Woosley and Taam (1976), Maraschi
  and Cavaliere (1977), Fujimoto et al. (1981)
• accretion rate ( 10-9 Msol / yr)
• Z of accreted matter
• ashes of previous bursts

intervals durations energies brightness
10
Type I X-ray bursts

• Discovery Grindlay et al. (1976), Belian et al.
  (1976)
• since then, over 80 such bursting systems have
  been observed!
• most frequent type of thermonuclear stellar
  explosion in the Galaxy
• third most energetic (Etot) after SN and
  classical novae

• Early models Woosley and Taam (1976), Maraschi
  and Cavaliere (1977), Fujimoto et al. (1981)
• accretion rate ( 10-9 Msol / yr)
• Z of accreted matter
• ashes of previous bursts

intervals durations energies brightness
Oversimplified nuclear physicsapproximation
networks
11
Type I X-ray bursts
Ayasli and Joss (1982)
12
Type I X-ray bursts

• Discovery Grindlay et al. (1976), Belian et al.
  (1976)
• since then, over 80 such bursting systems have
  been observed!
• most frequent type of thermonuclear stellar
  explosion in the Galaxy
• third most energetic (Etot) after SN and
  classical novae

• Early models Woosley and Taam (1976), Maraschi
  and Cavaliere (1977), Fujimoto et al. (1981)
• accretion rate ( 10-9 Msol / yr)
• Z of accreted matter
• ashes of previous bursts

intervals durations energies brightness
Oversimplified nuclear physicsapproximation
networks
Later models
Nuclear network calculations
Schatz et al. (2001) large (637 isotopes, H
Xe) one-zone, no convection Koike et al. (2004)
large (1270 isotopes, H Bi) one-zone, no
convection Woosley et al. (2004) adaptive (1300
isotopes, H Po) hydrodynamic Fisker et al.
(2008) moderate (298 isotopes, H
Te) hydrodynamic
13
Type I X-ray bursts vs. Classical nova explosions
Compact object neutron star
white dwarf Lmax 104 - 105 Lsol
104 - 105 Lsol ?tlightcurve 10 - 100 s
days months trec
hr days 104 - 105
yr Tp 1 2 GK 0.1
0.4 GK Galaxy 100 systems
30 / yr inferred Ejecta ???
10-4 10-5 Msol/nova
nucleosynthesis H Te
H Ca processes
? mostly theoretical ? mostly
experimental
14
MORE on Type I X-ray bursts
http//www.nscl.msu.edu/schatz/

• rp process! (Wallace and Woosley 1981)

Z
N
15
MORE on Type I X-ray bursts
http//www.nscl.msu.edu/schatz/

• rp process! (Wallace and Woosley 1981)

Z
classical novae!
N
16
MORE on Type I X-ray bursts
http//www.nscl.msu.edu/schatz/

• rp process! (Wallace and Woosley 1981)

72Kr
68Se
64Ge
Waiting points
Z
64Ge t1/2 1.1 min 68Se t1/2 36 s 72Kr t1/2
17 s
classical novae!
N
17
Type I XRBs Sensitivity to Nuclear Uncertainties
What should we measure to better constrain
predictions of nucleosynthesis and light curves
in XRBs?
18
Type I XRBs Sensitivity to Nuclear Uncertainties
What should we measure to better constrain
predictions of nucleosynthesis and light curves
in XRBs?
Limited studies Wallace and
Woosley (1981), Schatz et al. (1998), Koike et
al. (1999), Thielemann et al.
(2001), Fisker et al. (2004, 2006, 2007), Woosley
et al. (2004) ? effects of different entire
networks, few specific reaction variations, or
variations of groups of rates
19
Our Type I XRB sensitivity study!
10 scenarios exploring sensitivity in the
parameter space of thermodynamic histories ?
model, Tpeak, duration, initial composition

• Network 606 isotopes (H Xe)
• Techniques
• Individual variation of each of gt 2000 nuclear
  rates within uncertainties (Parikh et al. 2008)
• Simultaneous variation of nuclear rates within
  uncertainties (Parikh et al. 2008)
• Individual variation of each reaction with Q lt 1
  MeV within its ?Q (Parikh at al. in prep)

Effect of Tpeak (2 cases)
Schatz et al. (2001)
Koike et al. (2004)
Duration (2 cases)
Fisker et al. (2008)
(XYZ)initial (3 cases)
20
Our Type I XRB sensitivity study!
10 scenarios exploring sensitivity in the
parameter space of thermodynamic histories ?
model, Tpeak, duration, initial composition

• Network 606 isotopes (H Xe)
• Techniques
• Individual variation of each of gt 2000 nuclear
  rates within uncertainties (Parikh et al. 2008)
• Simultaneous variation of nuclear rates within
  uncertainties (Parikh et al. 2008)
• Individual variation of each reaction with Q lt 1
  MeV within its ?Q (Parikh at al. in prep)

Effect of Tpeak (2 cases)
Schatz et al. (2001)
Koike et al. (2004)
Duration (2 cases)
Fisker et al. (2008)
(XYZ)initial (3 cases)
e.g. for Technique 1 10 models x gt2000 rates x 2
(max min rate) gt40 000 individual XRB model
calculations

x 20 min/calc gt19 CPU-months
21
Our Type I XRB sensitivity study!
Rationale for varying rates and Q-values
The Q-value enters twice (1) in the
calculation of the HF (forward) rate (along with
level density, choice of potential
model) ?Recall that the majority of XRB rates
have no experimental information available! (2)
in the calculation of the reverse rate
If Q is large reverse rate suppressed! No
equilibrium! The rate is important, ?Q not so
much If Q is small reverse rate competes!
Equilibrium! ?Q is important, the rate not so
much
22
Our Type I XRB sensitivity study!
What can we learn by constraining XRB yields?
Neutron star crust effects
? compositional inertia Taa80
Affects light curves directly Woo04
Sedimentation affects subsequent H/He ignition
Pen07
? Ashes determine sth, sel
Evolution of magnetic field Bro98a
Quiescent luminosity Bro98b
? Subsequent C-powered superburst? Woo76, Cum01
Ejection of material?
? p-nuclei abundances (92,94Mo, 96,98Ru)? Sch98,
Sch01, Arn03
Observation of photoionization edges?
? Measurement of NS gravitational redshift?
Bil03, Wei06
23
Type I XRBs Sensitivity to Nuclear Uncertainties
What should we measure to better constrain
predictions of nucleosynthesis and light curves
in XRBs?
RESULTS
24
Our Type I XRB sensitivity study Models
Model Zi ?t (s) Tpeak(GK)
K04 0.02 100 1.36 F08 0.19 50 0.99 S01 0.001 30
0 1.91 hiT 0.02 100 2.50 lowT 0.02 100 0.90 lo
ng 0.02 1000 1.36 short 0.02 10 1.36 lowZ 0.0001
100 1.36 hiZ 0.19 100 1.36
K04 parameterized
Parikh, José, Moreno and Iliadis, ApJS 178 (2008)
110.
25
Our Type I XRB sensitivity study Models
Model Zi ?t (s) Tpeak(GK)
Xfmax End (Xf gt 0.01) K04 0.02 100 1.36
H, 68Ge, 72Se, 64Zn, 76Kr
96Ru F08 0.19 50 0.99 60Ni, 56Ni, 4He, 28Si, 12C
72Se S01 0.001 300 1.91 104Ag, 106Cd,
105Ag, 103Ag, H 107Cd hiT 0.02 100 2.50 H, 72Se,
68Ge, 76Kr, 80Sr 103Ag lowT 0.02 100 0.90 64Zn,
68Ge, H, 72Se, 60Ni 82Sr long 0.02 1000 1.36 68Ge
, 72Se, 104Ag, 76Kr, 103Ag 106Cd short 0.02 10 1.3
6 H, 64Zn, 60Ni, 4He, 68Ge 68Ge lowZ 0.0001 100 1
.36 68Ge, H, 72Se, 64Zn, 76Kr 96Ru hiZ 0.19 100 1
.36 56Ni, 60Ni, 64Zn, 39K, 68Ge 72Se
K04 parameterized
Parikh, José, Moreno and Iliadis, ApJS 178 (2008)
110.
26
Our Type I XRB sensitivity study rate variations
Important reaction rates to determine!
Reaction AME03 Q-value
Reaction AME03 Q-value
b Q and ?Q estimated from systematics
No experimental rate information available for
any of these!
Parikh, José, Moreno and Iliadis, ApJS 178 (2008)
110.
27
Our Type I XRB sensitivity study rate variations
Important reaction rates to determine!
Reaction AME03 Q-value
Reaction AME03 Q-value
b Q and ?Q estimated from systematics
No experimental rate information available for
any of these!
Parikh, José, Moreno and Iliadis, ApJS 178 (2008)
110.
28
Our Type I XRB sensitivity study rate variations
These affect BY FAR the most Xf in the most XRB
Models, incl. many Xfmax!
Reaction AME03 Q-value
Nuclear energy generation too!

• Need experimental
• Q-values
• Structure information for 62Ge and 66Se above
  p-thresholds

?(keV) t1/2 (ms)
61Ga -47090(53) 168(3) 62Ge -42243(140)b 130(40)
65As -46981(302)b 170(30) 66Se -41722(298)b 33(12
)
b Q and ?Q estimated from systematics
Parikh, José, Moreno and Iliadis, ApJS 178 (2008)
110.
29
Our Type I XRB sensitivity study Q-value
variations
PRELIMINARY RESULTS!
1. (a,?) reactions with Q lt 1 MeV varying
these by ?Q had no effect on Xf of any isotope,
in any XRB Model 2. (a,p) reactions with Q lt 1
MeV varying these by ?Q had no effect on Xf of
any isotope, in any XRB Model 3. (p,?) reactions
with Q lt 1 MeV only 15 reactions had any
effect on Xf of any isotope, when varied by their
?Q (Here, a change ? in the final XRB
yield Xf of an isotope is significant if ? gt
x2, for isotopes Xf gt 10-5.)
Parikh, José, Moreno, Iliadis and Rauscher, in
preparation
30
Our Type I XRB sensitivity study Q-value
variations
Precision Q-value measurements desired to better
constrain XRB nucleosynthesis in our Models
Reaction AME03 Q-value (keV)
25Si(p,?)26P 140 (96) 26P(p,?)27S
719 (281) 30S(p,?)31Cl 294
(50) 42Ti(p,?)43V 192 (233) 45Cr(p,?)46Mn
694 (515) 46Cr(p,?)47Mn 78
(160) 50Fe(p,?)51Co 88 (161) 55Ni(p,?)56Cu
555 (140) 60Zn(p,?)61Ga 192
(54) 64Ge(p,?)65As -80 (300) 68Se(p,?)69Br
-450 (100) 89Ru(p,?)90Rh 992
(711) 98Cd(p,?)99In 932 (408) 105Sn(p,?)106Sb
357 (323) 106Sn(p,?)107Sb 518 (302)
estimated from systematics
Parikh, José, Moreno, Iliadis and Rauscher, in
preparation
31
Our Type I XRB sensitivity study Q-value
variations
Precision Q-value measurements desired to better
constrain XRB nucleosynthesis in our Models
Reaction AME03 Q-value (keV)
?Q in 64Ge(p,?)65As affects BY FAR the most Xf in
the most XRB Models! The 64Ge mass has been
measured Clark et al. 2007 ?(64Ge) -54344(30)
keV Schury et al. 2007 ?(64Ge) -54315.7(3.8)
keV Again, it is CRITICAL to measure (for the
first time) the mass of 65As! AME03 ?(65As)
-46981(302) keV NUBASE03 t1/2(65As)
170(30) ms
25Si(p,?)26P 140 (96) 26P(p,?)27S
719 (281) 30S(p,?)31Cl 294
(50) 42Ti(p,?)43V 192 (233) 45Cr(p,?)46Mn
694 (515) 46Cr(p,?)47Mn 78
(160) 50Fe(p,?)51Co 88 (161) 55Ni(p,?)56Cu
555 (140) 60Zn(p,?)61Ga 192
(54) 64Ge(p,?)65As -80 (300) 68Se(p,?)69Br
-450 (100) 89Ru(p,?)90Rh 992
(711) 98Cd(p,?)99In 932 (408) 105Sn(p,?)106Sb
357 (323) 106Sn(p,?)107Sb 518 (302)
Nuclear energy generation too!
estimated from systematics
Parikh, José, Moreno, Iliadis and Rauscher, in
preparation
32
Measurements most desired to constrain XRB
nucleosynthesis in our models

• Masses of 62Ge, 65As, 66Se
• Structure of 62Ge and 66Se above p-threshold

ASCI Blue Pacific/LLNL
33
Measurements most desired to constrain XRB
nucleosynthesis in our models

• Masses of 62Ge, 65As, 66Se
• Structure of 62Ge and 66Se above p-threshold

ASCI Blue Pacific/LLNL
COLLABORATORS J. José F. Moreno C.
Iliadis T. Rauscher
34
Our Type I XRB sensitivity study rate variations
Monte-Carlo
Koike et al. (2004) T-?-t profile
Parikh, José, Moreno and Iliadis, ApJS 178 (2008)
110.
35
Our Type I XRB sensitivity study rate variations
Monte-Carlo
Koike et al. (2004) T-?-t profile
Part 2 Part
1 15N 15O(a,?) -0.78 15O(a,?),
18Ne(a,p) 65Zn 65Ge(p,?) -0.85 65As(p,?),
65Ge(p,?) 66Ge 66As(p,?) -0.58 65As(p,?),
66Ge(p,?), 66As(p,?) 66Ge(p,?)
-0.57 69Ge 69Se(p,?) -0.97 69Se(p,?) 73Se 73Kr
(p,?) -0.97 73Kr(p,?) 104Ag 103In(p,?)
0.60 65As(p,?),102In(p,?), 103In(p,?) 105Ag 104In
(p,?) 0.55 103In(p,?), 104In(p,?)
Parikh, José, Moreno and Iliadis, ApJS 178 (2008)
110.
36
Our Type I XRB sensitivity study rate variations
Monte-Carlo
Koike et al. (2004) T-?-t profile
Part 2 Part
1 15N 15O(a,?) -0.78 15O(a,?),
18Ne(a,p) 65Zn 65Ge(p,?) -0.85 65As(p,?),
65Ge(p,?) 66Ge 66As(p,?) -0.58 65As(p,?),
66Ge(p,?), 66As(p,?) 66Ge(p,?)
-0.57 69Ge 69Se(p,?) -0.97 69Se(p,?) 73Se 73Kr
(p,?) -0.97 73Kr(p,?) 104Ag 103In(p,?)
0.60 65As(p,?),102In(p,?), 103In(p,?) 105Ag 104In
(p,?) 0.55 103In(p,?), 104In(p,?)
Individual or simultaneous variation? ?
COMPLEMENTARY approaches!
Parikh, José, Moreno and Iliadis, ApJS 178 (2008)
110.