Neutrino emission

The effect of thermal pion fluctuations on the specific heat and the neutrino emissivity of neutron stars was discussed in [27, 28] together with other in-medium effects, see also reviews [29, 30], Neutron pair breaking and formation (PBF) neutrino process on the neutral current was studied in [31, 32] for the hadron matter. Also ref. [32] added the proton PBF process in the hadron matter and correlation processes, and ref. [33] included quark PBF processes in quark matter. PBF processes were studied by two different methods with the help of Bogolubov transformation for the fermion wave function [31, 33] and within Schwinger-Kadanoff-Baym-Keldysh formalism for nonequilibrium normal and anomalous fermion Green functions [32, 28, 29],... 

The first simulations of the collapsar scenario have been performed using 2D Newtonian, hydrodynamics (MacFadyen Woosley 1999) exploring the collapse of helium cores of more than 10 M . In their 2D simulation MacFadyen Woosley found the jet to be collimated by the stellar material into opening angles of a few degrees and to transverse the star within 10 s. The accretion process was estimated to occur for a few tens of seconds. In such a model variability in the lightcurve could result for example from (magneto-) hydrodynamic instabilities in the accretion disk that would translate into a modulation of the neutrino emission/annihilation processes or via Kelvin-Helmholtz instabilities at the interface between the jet and the stellar mantle. 

The following stage is core collapse caused by electron capture or photodisintegration of iron. According to the traditional view, collapse leads to formation of a neutron star which cools by neutrino emission and decompression of matter when it reaches nuclear density (10 g cm ). The rebound that follows generates a shock wave which is capable of reigniting a good few nuclear reactions as it moves back out across the stellar envelope. 

Fig. 5.4. Schematic evolution of the internal structure of a star with 25 times the mass of the Sun. The figure shows the various combustion phases (shaded) and their main products. Between two combustion phases, the stellar core contracts and the central temperature rises. Combustion phases grow ever shorter. Before the explosion, the star has assumed a shell-like structure. The centre is occupied by iron and the outer layer by hydrogen, whilst intermediate elements are located between them. CoUapse followed by rebound from the core generates a shock wave that reignites nuclear reactions in the depths and propels the layers it traverses out into space. The collapsed core cools by neutrino emission to become a neutron star or even a black hole. Most of the gravitational energy liberated by implosion of the core (some 10 erg) is released in about 10 seconds in the form of neutrinos. (Courtesy of Marcel Amould, Universite Libre, Brussels.)...

Without it, there would be no neutrons and hence no atomic nuclei. Furthermore, it is responsible for neutrino emissions, for it is the weak force which governs the transformation of protons into neutrons, and this can only be beneficial for nuclear stability. 

The concept that neutrinos diffuse out of the supernova core carrying out its thermal energy is confirmed by the observation of the neutrino burst from SN1987A for the first time. But we must keep in mind that there are some puzzles such as the last 3 events of Kamiokande. There may exist some unknown mechanism of neutrino emission at the late time. 

The radius of the neutrinosphere and duration time of neutrino emission are adjusted so that the total energy lost by neutrinos... 

COLLAPSE OF THE NEUTRON STAR INDUCED BY PHASE TRANSITIONS AND NEUTRINO EMISSION FROM SN1987A... 

NEUTRINO EMISSION PROCESSES IN THE WEINBERG-SALAM THEORY... 

The supernova 1987A in the Large Magellanic Cloud has provided a new opportunity to study the evolution of a young neutron star right after its birth. A proto-neutron star first cools down by emitting neutrinos that diffuse out of the interior within a minutes. After the neutron star becomes transparent to neutrinos, the neutron star core with > 1014 g cm-3 cools predominantly by Urea neutrino emission. However, the surface layers remain hot because it takes at least 100 years before the cooling waves from the central core reach the surface layers (Nomoto and Tsuruta 1981, 1986, 1987). 

Collapse of the Neutron Star Induced by Phase Transitions and Neutrino Emission from SN 1987A... 

Neutrino Emission Processes in the Weinberg-Salam Theory... 

Calculate the rate of fusion reactions in the sun. Be sure to correct for the energy loss due to neutrino emission. 

G.S. Bisnovatyi-Kogan Asymmetric neutrino emission and fromation of rapidly moving pulsars. In Proc. 8th Workshop on Nuclear Astrophysics. Ed. W.Hillebrandt, E. Muller (MPA Garching, 1996), p.41... 

In the end the endothermic disintegration of iron-group nuclei, the tightest bound of nuclei, precipitates core collapse. Evolutionary calculations [1] show that single stars with initial masses 20 — 30M leave cores of more than 1.8M . These promptly collapse to massive BHs (M > 1.8M )withno optical display, but intense neutrino emission from neutronization. For initial... 

Search for GRB Neutrinos. The AMANDA GRB search for correlated v emission relies on temporal (typically less than 100 s in duration) and angular information provided by BATSE and other satellites in the IPN network (Hurley et al., 1998). Initial search strategies for data collected between 1997-2000 (Hardtke et al., 2003) and for individual GRBs (Stamatikos et al., 2004), have assumed nearly concurrent emission within the duration of prompt gamma-ray emission (Tgo). A new search (Kuehn et al., 2004) also scans for neutrino emission prior to the Tgo start time. No excess was observed for either search method above the expected background from atmospheric v and poorly reconstructed... 

For p-decay processes (both and P" ) neutrino emission accompanied with electron emission as well as relativistic effects should be taken into account. Thus, the formula for the... 

In electron capture EC) decay, recoil by neutrino emission should be considered. Assuming the rest mass of the neutrino is zero, the recoil energy expression is similar to that in the photon... 

Nascent Neutron Star Boiling and Neutrino Emission... 

Neutron stars are thought to form in supernova explosions. The outer layers of the star crystallize as the newborn neutron star cools by neutrino emission. Estimates, based on the expected breaking strain of the crystal lattice, suggest that anisotropic stresses, which build up as the pulsar loses rotational energy, could lead to e < 10 the exact value depends on the breaking strain of the neutron... 

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