Regulated NiCu Cycles with the New <sup>57</sup>Cu(p,<i>γ</i>)<sup>58</sup>Zn Reaction Rate and the Influence on Type-I X-Ray Bursts: GS 1826–24 Clocked Burster
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EPJ Web Conf., EPJ Web Conf., 2021-09-21, Chengdu. 2022, vol. 260, p. 11023
English Abstract
<jats:p>In Type-I X-ray bursts (XRBs), the rapid-proton capture (rp-) process passes through the NiCu and ZnGa cycles before reaching the region above Ge and Se isotopes that hydrogen burning actively powers the XRBs. The ...Read more >
<jats:p>In Type-I X-ray bursts (XRBs), the rapid-proton capture (rp-) process passes through the NiCu and ZnGa cycles before reaching the region above Ge and Se isotopes that hydrogen burning actively powers the XRBs. The sensitivity study performed by Cyburt <jats:italic>et al</jats:italic>. [1] shows that the <jats:sup>57</jats:sup>Cu(p,<jats:italic>γ</jats:italic>)<jats:sup>58</jats:sup>Zn reaction in the NiCu cycles is the fifth most important rp-reaction influencing the burst light curves. Langer <jats:italic>et al</jats:italic>. [2] precisely measured some low-lying energy levels of <jats:sup>58</jats:sup>Zn to deduce the <jats:sup>57</jats:sup>Cu(p,<jats:italic>γ</jats:italic>)<jats:sup>58</jats:sup>Zn reaction rate. Nevertheless, the order of the 1<jats:sup>+</jats:sup><jats:sub>1</jats:sub> and 2<jats:sup>+</jats:sup><jats:sub>3</jats:sub> resonance states that dominate at 0:2 ≲ <jats:italic>T</jats:italic>(GK) ≲ 0:8 is not confirmed. The 1<jats:sup>+</jats:sup><jats:sub>2</jats:sub> resonance state, which dominates at the XRB sensitive temperature regime 0:8 ≲ <jats:italic>T</jats:italic>(GK) ≲ 2 was not detected. Using isobaric-multipletmass equation (IMME), we estimate the order of the 1<jats:sup>+</jats:sup><jats:sub>1</jats:sub> and 2<jats:sup>+</jats:sup><jats:sub>3</jats:sub> resonance states and estimate the lower limit of the 1<jats:sup>+</jats:sup><jats:sub>2</jats:sub> resonance energy. We then determine the <jats:sup>57</jats:sup>Cu(p,<jats:italic>γ</jats:italic>)<jats:sup>58</jats:sup>Zn reaction rate using the full <jats:italic>pf</jats:italic> -model space shell model calculations. The new rate is up to a factor of four lower than the Forstner <jats:italic>et al</jats:italic>. [3] rate recommended by JINA REACLIBv2.2. Using the present <jats:sup>57</jats:sup>Cu(p,<jats:italic>γ</jats:italic>)<jats:sup>58</jats:sup>Zn, the latest <jats:sup>56</jats:sup>Ni(p,<jats:italic>γ</jats:italic>)<jats:sup>57</jats:sup>Cu and <jats:sup>55</jats:sup>Ni(p,<jats:italic>γ</jats:italic>)<jats:sup>56</jats:sup>Cu reaction rates, and 1D implicit hydrodynamic K<jats:sc>epler</jats:sc> code, we model the thermonuclear XRBs of the clocked burster GS 1826–24. We find that the new rates regulate the reaction flow in the NiCu cycles and strongly influence the burst-ash composition. The <jats:sup>59</jats:sup>Cu(p,<jats:italic>γ</jats:italic>)<jats:sup>56</jats:sup>Ni and <jats:sup>59</jats:sup>Cu(p,<jats:italic>α</jats:italic>)<jats:sup>60</jats:sup>Zn reactions suppress the influence of the <jats:sup>57</jats:sup>Cu(p,<jats:italic>γ</jats:italic>)<jats:sup>58</jats:sup>Zn reaction. They strongly diminish the impact of the nuclear reaction flow that bypasses the <jats:sup>56</jats:sup>Ni waiting point induced by the <jats:sup>55</jats:sup>Ni(p,<jats:italic>γ</jats:italic>)<jats:sup>56</jats:sup>Cu reaction on burst light curve.</jats:p>Read less <
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