nuclear physics in x-ray binaries the rp-process and more open questions nuclear physics...
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Nuclear Physics in X-ray binariesthe rp-process and more
• Open questions• Nuclear physics uncertainties
• status of major waiting points• reaction rates
• mass ejection
H. SchatzMichigan State University
Joint Institute for Nuclear Astrophysics
X-ray bursts
(1735-444)15 s
Lines during bursts
Cottam, Paerels, Mendez 2002
EXO0748-676
KS 1731-260
NASA/Chandra/Wijnands et al.
Off-state Lum.
18 18.5time (days)
(4U 1735-44)
6 h
Superbursts
331
330
329
328
327
Fre
quen
cy (
Hz )
10 15 20Time (s)
4U1728-34
ms burst oscillations
StrohmayerBhattacharyya et al. 2004
cooling
cooling
cooling
M,R
M,R
Open Questions• multipeaked bursts ?• other unusual bursts ? (Chenevez et al. 2005)
• burst behavior > 0.13 medd ?• mass ejection, nucleosynthesis ?• information about m, accreted composition (distance), …?
Open Questions• how is sufficient iron column sustained ?• could other features be observable ? In which systems ?
Open Questions• what is the origin of the oscillations ? frequency drift ? (patchy burning, osc. Modes, …)• information about neutron star from pulse train analysis ?
Open Questions• C ignition model really the answer ? (or do we need strange stars ?)• information about NS crust and core ?
Open Questions• reconcile rapid cooling with superbursts ?• really indication for rapid core cooling ?• information about NS, NS crust and core ? (or issues with resdiual accretion)
Galloway et al. 2003
97-98
2000
Precision X-ray observations(NASA’s RXTE)
Woosley et al. 2003 astro/ph 0307425
Need much more precise nuclear data to make full use of high quality observational data
Uncertain models due to nuclear physics
Burst models withdifferent nuclear physicsassumptions (lifetimes!)
Burst models withdifferent nuclear physicsassumptions (lifetimes!)
GS 1826-24 burst shape changes ! (Galloway 2003 astro/ph 0308122)
H. Schatz
Reality Check: Comparison with Observations
Potential total delaytime of 170s(if all beta decay)
Potential total delaytime of 170s(if all beta decay)
64Ge
68Se
72Kr
Major progress in measurement of masses and half-lifes:
• most half-lives measured• precision mass measurements with traps are reaching the rp-process ANL (CPT), NSCL (LEBIT), CERN (ISOLTRAP)
observed
Half-life measured
Mass measured >10 keV
Mass measured <10 keV
64Ge
65As
66Se
m=32 keV(Clark et al. to be published)
m=141 keV (mirror: 100 keV)
m=104 keV (mirror: 30 keV)
H. Schatz
64Ge Waiting point current uncertaintylif
etim
e (s
)
Temperature (GK)
Mass uncertaintyMass uncertainty
65As(p,) x 10065As(p,) x 100
65As(p,) / 10065As(p,) / 10064Ge
Sp=-0.35
=92s
H. Schatz
68Se and 72Kr Waiting point current uncertainty
68Se
72Kr
Temperature (GK)
Life
time
(s)
Lif e
ti me
(s)
68Se
69Br
70Kr
m=19 keV(Clark et al. 2004)
m=110 keV (mirror: 34 keV)
m=120 keV (mirror: 62 keV)
72Kr
73Rb
74Sr
m=8.0 keV(Rodriguez et al. 2004)
m=100 keV (mirror: 6.6 keV) (Rodriguez et al. 2004)
m=100 keV (mirror: 2.1 keV) (Rodriguez et al. 2004)
Sp=-0.81
Sp=-0.7
=51s
=25s
0 1
23 4
5 6
7 8
9 10
11 12 13
14
15 16
17 18 19 20
21 22
23 24
25 26 27 28
29 30
31 32
33 34 35 36
37 38 39 4041
42 43 44
45 46 47 48
49 5051 52
5354 55
56
57 58
n (0) H (1)
H e (2)L i (3)
Be (4) B (5) C (6) N (7)
O (8) F (9)
N e (10)N a (11)
M g (12)A l (13)S i (14) P (15)
S (16)C l (17)
A r (18) K (19)
C a (20)Sc (21)
Ti (22) V (23)
C r (24)M n (25)
Fe (26)C o (27)
N i (28)C u (29)
Zn (30)G a (31)
G e (32)As (33)
Se (34)B r (35)K r (36)R b (37)
S r (38) Y (39)
Zr (40)N b (41)
M o (42)Tc (43)
R u (44)R h (45)Pd (46)Ag (47)
C d (48)In (49)
Sn (50)Sb (51)
Te (52) I (53)
Xe (54)
H. Schatz
rp-process reaction rates
some experimental information available(most rates are still uncertain)
Indirect studies example at NSCL:p(34A, 33Ar)d
to study 32Cl(p,)33Arfirst experiment by R. Clementprogram further developed by D. Galaviz M. Amthor, …
Indirect studies example at NSCL:p(34A, 33Ar)d
to study 32Cl(p,)33Arfirst experiment by R. Clementprogram further developed by D. Galaviz M. Amthor, …
Theoretical reaction rate predictions difficult neardrip line as single resonances dominate rate:
Hauser-Feshbach: not applicable
Shell model: available up to A~63 but large uncertainties (often x1000 - x10000)
(Herndl et al. 1995, Fisker et al. 2001)
Need experiments
x10000 uncertainty
shell model only
-rays from predicted 3.97 MeV state
Doppler corrected -rays in coincidence with 33Ar in S800 focal plane:
33Ar level energies measured:
3819(4) keV (150 keV below SM)3456(6) keV (104 keV below SM)
33Ar level energies measured:
3819(4) keV (150 keV below SM)3456(6) keV (104 keV below SM)
H. Schatz
reac
tion
rate
(cm
3/s
/mol
e)
temperature (GK)
x 3 uncertaintywith experimental data
stellar reaction rate
New 32Cl(p,)33Ar rate – Clement et al. PRL 92 (2004) 2502
Typical X-ray burst temperatures
34Ar (p,d) 33Ar* 33Ar
Study states in 33Ar via:
MSU/NSCL Experiment
Note: SEF 4-5from capture on 1st excited state in 32Cl
Note: SEF 4-5from capture on 1st excited state in 32Cl
H. Schatz
Mass ejection in X-ray bursts ? Weinberg, Bildsten, Schatz 2005
• Analytic model of burst rise radiative zone plus convection zone
Tem
pera
ture
(K
)
Column density (g/cm2)
Initial ra
diative profile
• Initially: gr < th
• Example: pure He accretor
wind
Burned matter can be ejected In wind during radius expansion bursts Similar for low accretion rate Mixed H/He accretors that ignite pure He layer
?
Nevin Weinberg:
H. Schatz
Reaction flow during burst rise in pure He flash
12C
13N
16O
slow
(p,)
(,p)
12C() bypass
Need protons as catalysts(~109 are enough !)
Source: (,p) reactionsand feedback through bypass
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Composition of ejected material
32S28S
Weak p-captureon initial Fe seed
Observable with current X-ray telescopes
in wind on NS surface
Explanation for enhanced Ne/O ratio in 4U1543-624 and 4U1850-087 ?
Observable with current X-ray telescopes
in wind on NS surface
Explanation for enhanced Ne/O ratio in 4U1543-624 and 4U1850-087 ?
• Lots of open questions related to X-ray binaries
• Nuclear physics plays a critical role in majority of observables
• There is still a lot of nuclear physics to do to address major uncertainties• half-lives (role of excited parent states)• masses• reaction rates (direct and indirect techniques needed)
• Burned material can be ejected in X-ray bursts that exhibit winds
• mainly Si, S produced during burst raise, some Zn,Ge
• can rp-process ashes be ejected ???
a) If burst ignites in rp-ashes from preceding bursts ?b) In superbursts ?
• composition is observable direct constraints in nuclear burning (look for pure He accretors or H/He accretors at low accretion rates)
H. Schatz
Summary
H. Schatz
H/He flash burst rise
H. Schatz
Composition of ejected material
wind
withbypass
H. Schatz
Effects of bypass
• Nucleosynthesis (heavier nuclei produced)• boost in energy generation prevents receding of convection zone• burst lightcurve
Effects of onset of bypass at around 1 GK
Early burst lightcurve
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