Neutrino energy loss by electron capture on strongly screened iron group nuclei

The influences on the neutrino energy loss rates in iron group nuclei at the same density are investigated in the presence of strong electron screening and in the absence of electron screening. The results show that at a temperature of 15 × 10^9 K, the neutrino energy loss rates which come from the electron capture process for most iron group nuclei decrease no more than 2 orders of magnitude but for the others （such as ^53,55,56,57,58,59,6o Co, ^56,59Ni） they can decrease about 3 orders of magnitude due to strong electron screening （SES）, whereas, at a temperature of 10^9K the neutrino energy loss rates of the most iron group nuclei can be diminished greatly due to the SES. For example, ^61Fe, ^60Fe, and ^62Ni the neutrino energy loss rates decrease about 4, 15 and 16 orders of magnitude and for ^57Cr, ^58Cr, and ^60Cr decrease about 18, 12, and 10 orders of magnitude respectively. According to our calculations the neutrino energy loss rates of nuclei ^58Mn, ^59Mn, ^60Mn, and ^62Mn may decrease about 13 orders of magnitude at a temperature of 10^9 K due to the SES.

Bremsstrahlung neutrino energy loss for ^(24)Mg,^(28)Si,^(32)S,^(40)Ca,^(56)Fe in strong electron screening

Based on Weinberg-Salam theory the bremsstrahlung neutrino energy loss for nuclei ^24Mg, ^28Si,^32S, ^40Ca and ^56Fe are investigated in strong electron screening. Our results are compared with those of Dicus＇ and show that the latter are higher by 2 orders of magnitude in the density-temperature region of 10^8 g/cm^3 ≤p/μe ≤ 10^11 g/cm^3 and 2.5≤ T9≤ 4.5. On the other hand, the factor C shows that the maximum differences are 99.16%, 99.13%, 99.12%, 99.055%, 99.040% corresponding to the nuclei ^24Mg, ^28Si, ^32S, ^40Ca and ^56Fe.

Pair neutrino energy loss for nuclei ^(56)Fe at the late stages of stellar evolution

t Based on the Weinberg-Salam theory, the pair neutrino energy loss rates for nuclei 56^Fe are canvassed for the wide range of density and temperature. The results of ours （QLJ） are compared with those ofBeaudet G, Petrosian V and Salpeter E. E＇s （QBPs）, and it shows that the pair neutrino energy loss rates of QBPS are always larger than QLJ .The QBPS is 12.57%, 12.86%, 14.99%, 19.80% times higher than QLJ corresponding to the temperature T9=0.385, 1.0, 5.0, 10, respectively.

Neutrino energy loss by electron capture in magnetic field at the crusts of neutron stars

Based on the p-f shell model, the effect of strong magnetic field on neutrino energy loss rates by electron capture is investigated. The calculations show that the magnetic field has only a slight effect on the neutrino energy loss rates in the range of 10^8-10^13 G on the surfaces of most neutron stars. But for some magnetars, the range of the magnetic field is 10^13-10^18 G, and the neutrino energy loss rates are greatly reduced, even by more than four orders of magnitude due to the strong magnetic field.

Gaussian modification of neutrino energy loss on strongly screening nuclides ^(55)Co and ^(56)Ni by electron capture in stellar interior

Gaussian modifications of the neutrino energy loss （NEL） by electron capture on the strongly screening nuclides 55Co and 56Ni are investigated. The results show that in strong electron screening （SES）, the NEL rates decrease without modifying the Gamow-Teller （G-T） resonance transition. For instance, the NEL rates of 55Co and 56Ni decrease more than two and three orders of magnitude for ρ7 = 5.86, T9 5, Ye = 0.47, △ = 6.3, respectively. In contrast, due to Gaussian modification, the NEL rates increase about two orders of magnitude in SES. Due to SES, the maximum values of the C-factor （in %） on NEL of 55Co, 56Ni are of the order of 99.80%, 99.56% at ρ7 = 5.86 Ye = 0.47 and 99.60%, 99.65% at ρ7 = 106 Ye = 0.43, respectively.

Plasma neutrino energy loss due to the axial-vector current at the late stages of stellar evolution

Based on the Weinberg-Salam theory, the plasma neutrino energy loss rates of vector and axialvector contributions are studied. A ratable factor of the rates from the axial-vector current relative to those of the total neutrino energy loss rates is accurately calculated. The results show that the ratable factor will reach a maximum of 0.95 or even more at relatively higher temperature and lower density （such as p/μe 〈 10^7 g/cm^3）. Thus the rates of the axial-vector contribution cannot be neglected. On the other hand, the rates of the axialvector contribution are on the order of ~0.01% of the total vector contribution, which is in good agreement with Itoh＇s at relatively high density （such as p/μe 〉 10^7 g/cm^3） and a temperature of T ≤ 10^11 K.