X-ray bursts from thermonuclear runaways on accreting neutron stars

Taam, R. E.

doi:10.1086/158348

Cited by 56 publications

(56 citation statements)

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“…Two possible explanations for the discrepancy are (i) extra heating, e.g. from thermal or compositional inertia effects [51,60], or (ii) the fraction of the star covered by fuel changes withṀ . Future comparisons with time-dependent simulations or improved spectral models should test these ideas.…”

Section: Comparison With Observa-tionsmentioning

confidence: 99%

Thermonuclear X-ray bursts: theory vs. observations

Cumming

2004

Nuclear Physics B - Proceedings Supplements

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I review our theoretical understanding of thermonuclear flashes on accreting neutron stars, concentrating on comparisons to observations. Sequences of regular Type I X-ray bursts from GS 1826-24 and 4U 1820-30 are very well described by the theory. I discuss recent work which attempts to use the observed burst properties in these sources to constrain the composition of the accreted material. For GS 1826-24, variations in α with accretion rate indicate that the accreted material has solar metallicity; for 4U 1820-30, future observations should constrain the hydrogen fraction, testing evolutionary models. I briefly discuss the global bursting behavior of burst sources, which continues to be a major puzzle. Finally, I turn to superbursts, which naturally fit into the picture as unstable carbon ignition in a thick layer of heavy elements. I present new time-dependent models of the cooling tails of superbursts, and discuss the various interactions between superbursts and normal Type I bursts, and what can be learned from them.

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Section: Comparison With Observa-tionsmentioning

confidence: 99%

Thermonuclear X-ray bursts: theory vs. observations

Cumming

2004

Nuclear Physics B - Proceedings Supplements

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“…By considering all possible scattering positions and comparing the calculated residual alpha particle energy with the measurement, a unique solution is found within the uncertainties. where Y α is the yield of alpha particles at each energy bin, S (E beam ) is the stopping power of He+CO 2 for 30 S, I30 S is the number of 30 S ions injected, n is the number density of 4 He in the active target, ΔE is the energy bin size, ΔΩ is the solid angle at a given energy bin, and m α & m30 S are the mass of 4 He & 30 S, respectively. Several of these quantities are quite trivial to determine, such as the atomic masses, the number of helium atoms in the target, yield of alpha particles, and energy binning employed.…”

Section: Resultsmentioning

confidence: 99%

“…The resonance energy E r is just the elastic scattering center-of-mass energy E cm . As both nuclides in the entrance channel, 30 S and 4 He, have a spin-parity J π = 0 + , then each value corresponds to a unique resonance J π r assignment in the compound nucleus 34 Ar as no orbital momentum can be transferred and the parity will always be natural. We can initially estimate Γ α starting from the Wigner limit, and decreasing the width until the resonance height is matched.…”

Section: Resultsmentioning

confidence: 99%

“…In XRBs, where the nuclear reaction network includes hundreds of species and thousands of nuclear transmutations, it is actually only a small subset of these nuclear transmutations which need to be known precisely, as they make a predominant contribution to the nuclear trajectory to higher mass and energy generation. The 30 S(α, p) reaction is identified as one such important reaction, contributing more than 5% to the total energy generation [2], influencing the neutron star crustal composition [3] relevant to compositional inertia [4], moving material away from the 30 S waiting point [5], and possibly accounting for double-peaked XRBs [6].…”

Section: Introductionmentioning

confidence: 99%

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Experimental investigation of the³⁰S(α, p) thermonuclear reaction in x-ray bursts

Kahl

Chen

Kubono

et al. 2016

EPJ Web of Conferences

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Abstract. We performed the first measurement of 30 S+α resonant elastic scattering to experimentally examine the 30 S(α, p) stellar reaction rate in type I x-ray bursts. These bursts are the most frequent thermonuclear explosions in the galaxy, resulting from thermonuclear runaway on the surface of accreting neutron star binaries. The 30 S(α, p) reaction plays a critical role in burst models, yet very little is known about the compound nucleus 34 Ar at these energies nor the reaction rate itself. We performed a measurement of alpha elastic scattering with a radioactive beam of 30 S to experimentally probe the entrance channel. Utilizing a gaseous active target system and silicon detector array, we extracted the excitation function from 1.8 to 5.5 MeV near 160 • in the center-of-mass frame. The experimental data were analyzed with an R-Matrix calculation, and we discovered several new resonances and extracted their quantum properties (resonance energy, width, spin, and parity). Finally, we calculated the narrow resonant thermonuclear reaction rate of 30 S(α, p) for these new resonances.

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“…Also, the reheating of burst ashes by successive bursts will further process the nuclear material. The resulting abundances in deeper layers of the neutron star crust, specifically that of carbon, are relevant to superburst processes [1,2].…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of Type I X-Ray Bursts to rp-Process Reaction Rates

Amthor¹,

Galaviz²,

Heger³

et al. 2010

Proceedings of International Symposium on Nuclear Astrophysics - Nuclei in the Cosmos - IX — PoS(NIC-IX)

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First steps have been taken in a more comprehensive study of the dependence of observables in Type I X-ray bursts on uncertain (p,γ) reaction rates along the rp-process path. We use the multizone hydrodynamics code KEPLER which implicitly couples a full nuclear reaction network of more than 1000 isotopes, as needed, to follow structure and evolution of the X-ray burst layer and its ashes. This allows us to incorporate the full rp-process network, including all relevant nuclear reactions, and individually study changes in the X-ray burst light curves when modifying selected key nuclear reaction rates. In this work we considered all possible proton captures to nuclei with 10 < Z < 28 and N ≤ Z. When varying individual reaction rates within a symmetric full width uncertainty of a factor of 10 4 , early results for some rates show changes in the burst light curve as large as 10 percent of peak luminosity. This change is large enough to be detectable by current X-ray burst light curve observations. More precise reaction rates are therefore needed to test current X-ray burst models, particularly of the burst rise, with observational data and to constrain astrophysical parameters.

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X-ray bursts from thermonuclear runaways on accreting neutron stars

Cited by 56 publications

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Thermonuclear X-ray bursts: theory vs. observations

Thermonuclear X-ray bursts: theory vs. observations

Experimental investigation of the³⁰S(α, p) thermonuclear reaction in x-ray bursts

Sensitivity of Type I X-Ray Bursts to rp-Process Reaction Rates

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X-ray bursts from thermonuclear runaways on accreting neutron stars

Cited by 56 publications

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Thermonuclear X-ray bursts: theory vs. observations

Thermonuclear X-ray bursts: theory vs. observations

Experimental investigation of the30S(α, p) thermonuclear reaction in x-ray bursts

Sensitivity of Type I X-Ray Bursts to rp-Process Reaction Rates

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Experimental investigation of the³⁰S(α, p) thermonuclear reaction in x-ray bursts