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Article overview
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Supernova Neutrino Opacity from Nucleon-Nucleon Bremsstrahlung and Related Processes | Steen Hannestad
; Georg Raffelt
; | Date: |
12 Nov 1997 | Journal: | Astrophys.J. 507 (1998) 339-352 | Subject: | astro-ph hep-ph | Abstract: | Elastic scattering on nucleons,
u N -> N
u, is the dominant supernova (SN) opacity source for mu and au neutrinos. The dominant energy- and number-changing processes were thought to be
u e^- -> e^-
u and
uar
u <-> e^+ e^- until Suzuki (1993) showed that the bremsstrahlung process
uar
u NN <-> NN was actually more important. We find that for energy exchange, the related ``inelastic scattering process’’
u NN <-> NN
u is even more effective by about a factor of 10. A simple estimate implies that the
u_mu and
u_ au spectra emitted during the Kelvin-Helmholtz cooling phase are much closer to that of
uar_e than had been thought previously. To facilitate a numerical study of the spectra formation we derive a scattering kernel which governs both bremsstrahlung and inelastic scattering and give an analytic approximation formula. We consider only neutron-neutron interactions, we use a one-pion exchange potential in Born approximation, nonrelativistic neutrons, and the long-wavelength limit, simplifications which appear justified for the surface layers of a SN core. We include the pion mass in the potential and we allow for an arbitrary degree of neutron degeneracy. Our treatment does not include the neutron-proton process and does not include nucleon-nucleon correlations. Our perturbative approach applies only to the SN surface layers, i.e. to densities below about 10^{14} g cm^{-3}. | Source: | arXiv, astro-ph/9711132 | Services: | Forum | Review | PDF | Favorites |
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