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

H. Schatz

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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