Nuclear Physics in X-ray binaries the rp-process and more Open questions Nuclear physics uncertainties status of major waiting points reaction rates mass ejection H. Schatz Michigan State University Joint Institute for Nuclear Astrophysics

X-ray bursts ( ) 15 s Lines during bursts Cottam, Paerels, Mendez 2002 EXO KS NASA/Chandra/Wijnands et al. Off-state Lum time (days) (4U ) 6 h Superbursts Frequency (Hz) Time (s) 4U ms burst oscillations Strohmayer Bhattacharyya et al  cooling  M,R Open Questions multipeaked bursts ? other unusual bursts ? (Chenevez et al. 2005) burst behavior > 0.13 m edd ? 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 Precision X-ray observations (NASA’s RXTE) Woosley et al astro/ph Need much more precise nuclear data to make full use of high quality observational data Uncertain models due to nuclear physics Burst models with different nuclear physics assumptions (lifetimes!)  GS burst shape changes ! (Galloway 2003 astro/ph ) H. Schatz Reality Check: Comparison with Observations

Potential total delay time of 170s (if all beta decay) Potential total delay time of 170s (if all beta decay) 64 Ge 68 Se 72 Kr 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

64 Ge 65 As 66 Se  m=32 keV (Clark et al. to be published)  m=141 keV (mirror: 100 keV)  m=104 keV (mirror: 30 keV) H. Schatz 64 Ge Waiting point current uncertainty lifetime (s) Temperature (GK) Mass uncertainty 65As(p,  ) x As(p,  ) / Ge Sp=-0.35  =92s

H. Schatz 68 Se and 72 Kr Waiting point current uncertainty 68 Se 72 Kr Temperature (GK) Lifetime (s) 68 Se 69 Br 70 Kr  m=19 keV (Clark et al. 2004)  m=110 keV (mirror: 34 keV)  m=120 keV (mirror: 62 keV) 72 Kr 73 Rb 74 Sr  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

H. Schatz rp-process reaction rates some experimental information available (most rates are still uncertain) Indirect studies example at NSCL: p( 34 A, 33 Ar)d to study 32 Cl(p,  ) 33 Ar first experiment by R. Clement program further developed by D. Galaviz M. Amthor, … Theoretical reaction rate predictions difficult near drip line as single resonances dominate rate: Hauser-Feshbach: not applicable Shell model: available up to A~63 but large uncertainties (often x 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: 33 Ar level energies measured: 3819(4) keV (150 keV below SM) 3456(6) keV (104 keV below SM) 33 Ar level energies measured: 3819(4) keV (150 keV below SM) 3456(6) keV (104 keV below SM) H. Schatz reaction rate (cm 3 /s/mole) temperature (GK) x 3 uncertainty with experimental data stellar reaction rate New 32 Cl(p,  ) 33 Ar rate – Clement et al. PRL 92 (2004) 2502 Typical X-ray burst temperatures 34 Ar  (p,d) 33 Ar*  33 Ar Study states in 33Ar via: MSU/NSCL Experiment Note: SEF 4-5 from capture on 1 st excited state in 32 Cl

H. Schatz Mass ejection in X-ray bursts ? Weinberg, Bildsten, Schatz 2005 Analytic model of burst rise radiative zone plus convection zone Temperature (K) Column density (g/cm 2 ) Initial radiative 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 12 C 13 N 16 O slow (p,  ) ( ,p) 12 C(  ) bypass Need protons as catalysts (~10  9 are enough !) Source: ( ,p) reactions and feedback through bypass

H. Schatz Composition of ejected material 32 S 28 S Weak p-capture on initial Fe seed  Observable with current X-ray telescopes  in wind  on NS surface  Explanation for enhanced Ne/O ratio in 4U and 4U ?  Observable with current X-ray telescopes  in wind  on NS surface  Explanation for enhanced Ne/O ratio in 4U and 4U ?

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

with bypass 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  -network only