Gamow-Teller strength distributions and neutrino energy loss rates due to chromium isotopes in stellar matter

Abstract

Gamow-Teller transitions in isotopes of chromium play a consequential role in the presupernova evolution of massive stars. β-decay and electron capture rates on chromium isotopes significantly affect the time rate of change of lepton fraction (Ẏ e ). Finetuning of this parameter is one of the key for simulating a successful supernova explosion. The (anti)neutrinos produced as a result of electron capture and β-decay are transparent to stellar matter during presupernova phases. They carry away energy and this result in cooling the stellar core. In this paper we present the calculations of Gamow-Teller strength distributions and (anti)neutrino energy loss rates due to weak interactions on chromium isotopes of astrophysical importance. We compare our results with measured data and previous calculations wherever available.

Strongly screened electron capture rates of chromium isotopes in presupernova evolution

“…According to our calculations, the GT transition EC reaction may not be the dominant process at lower tem- Table 1 Comparison of our results by SMMC for total strength, centroid and width of calculated GT strength distributions with those of NKK (Nabi et al 2016) perature. On the other hand, the higher the temperature is, the larger the electron energy, the larger the density and the higher the electron Fermi energy become.…”

“…However, any available experimental GT+ strength distributions for these nuclei can not obtained except for theoretical calculations. Table 1 present some information about the comparison of our results by SMMC for total strength, centroid and width of calculated GT strength distributions with those of NKK (Nabi et al 2016) for EC of 53−60 Cr. Our results of GT strength distributions calculated are higher than those of NKK.…”

“…Some studies have shown that β-decay and EC rates of chromium isotopes significantly affect the time rate of change of lepton fraction ( Ẏe ). For example, Nabi et al (2016) detailed the GT strength distributions, Ẏe and neutrino energy loss rates for chromium isotopes due to weak interactions in stellar matter. However, their works did not discuss the problem of how strong electron screening (SES) would effect EC.…”

“…Comparison of our results by SMMC for total strength, centroid and width of calculated GT strength distributions with those of NKK(Nabi et al 2016)for EC of 53−60 Cr.…”

Neutrino Spectra from Nuclear Weak Interactions in sd-Shell Nuclei under Astrophysical Conditions

“…Calculating the nuclear weak interaction processes that occur in the hydrostatic run-up to this end state is challenging. The potentially high temperatures and considerable electron Fermi energies characterizing material in the central regions of these stars imply that nuclear excited states contribute to important weak interactions in both neutral (Bahcall et al 1974;Fuller & Meyer 1991) and charged current channels (Bahcall 1964), and electron degeneracy can leverage the energy dependence of weak interaction processes, producing large continuum electron capture rates (Fuller et al 1980(Fuller et al , 1982a(Fuller et al ,b, 1985Oda et al 1994;Langanke & Martínez-Pinedo 1999, 2000Ferreira et al 2014;Langanke & Martínez-Pinedo 2014;Martínez-Pinedo et al 2014;Nabi et al 2016;Sarriguren 2016;Raduta et al 2017). Nuclear weak interactions also play important roles in many other extreme astrophysical environments (Woosley & Heger 2015;Iliadis et al 2016;Liu et al 2016;Mernier et al 2016;Mori et al 2016;Rahman & Nabi 2016;Suzuki et al 2016).…”