Properties of gamma-ray decay lines in 3D core-collapse supernova models, with application to SN 1987A and Cas A

ABSTRACT Comparison of theoretical line profiles to observations provides important tests for supernova explosion models. We study the shapes of radioactive decay lines predicted by current 3D core-collapse explosion simulations, and compare these to observations of SN 1987A and Cas A. Both the widths and shifts of decay lines vary by several thousand kilometres per second depending on viewing angle. The line profiles can be complex with multiple peaks. By combining observational constraints from 56Co decay lines, 44Ti decay lines, and Fe IR lines, we delineate a picture of the morphology of the explosive burning ashes in SN 1987A. For MZAMS = 15−20 M⊙ progenitors exploding with ∼1.5 × 1051 erg, ejecta structures suitable to reproduce the observations involve a bulk asymmetry of the 56Ni of at least ∼400 km s−1 and a bulk velocity of at least 1500 km s−1. By adding constraints to reproduce the UVOIR bolometric light curve of SN 1987A up to 600 d, an ejecta mass around 14 M⊙ is favoured. We also investigate whether observed decay lines can constrain the neutron star (NS) kick velocity. The model grid provides a constraint VNS > Vredshift, and applying this to SN 1987A gives a NS kick of at least 500 km s−1. For Cas A, our single model provides a satisfactory fit to the NuSTAR observations and reinforces the result that current neutrino-driven core-collapse SN models achieve enough bulk asymmetry in the explosive burning material. Finally, we investigate the internal gamma-ray field and energy deposition, and compare the 3D models to 1D approximations.

Experimental Challenge to Heavy Element Synthesis under Explosive Burning on Neutron Stars

Binary stellar systems that involve a neutron star or two neutron stars make interesting phenomena, X-ray bursts and kilo-novae, respectively, which involve explosive burning either in the proton-rich environment or in the neutron-rich environment. These are very important problems for nuclear astrophysics. First, the current effort for the explosive hydrogen burning, the rapid proton capture (rp) process which would take place on a neutron star surface in X-ray burst is discussed together with a new X-ray observation that suggests the rp-process termination at around A = 100. The observation of the afterglow of the binary neutron star merger appears to be the kilo-nova predicted in the last decade in nuclear astrophysics, and to be the great success of the field. However, the detailed study of the kilo-nova by the r-process should be a great challenge for full understanding heavy element synthesis and the neutron star merger. Nuclear physics problems are discussed for the kilonova.

Пороги инициирования и динамические характеристики взрыва для тонких образцов композитов ТЭН-Al при лазерном воздействии

In this paper, we measured thresholds H _cr of explosive decomposition of thin ( h = 1 mm) samples of PETN-Al composites with densities in the range of ρ = 0.9–1.7 g/cm^3 and variations in the concentration of aluminum inclusions in the range of 0.025–1.0 wt % upon exposure to pulses of a neodymium laser (λ = 1064 nm, 14 ns). For each ρ, inclusion concentrations n _opt, at which the threshold for explosive decomposition of H _cr is minimal, are obtained. The velocities of air shock waves (ASWs) were determined depending on sample density ρ, and the times of the start of explosive decomposition were determined depending on the inclusion concentration. The amplitude (in relative units) and time shift of the maximal pressure of an ASW at the piezodetector are determined depending on sample density. It is concluded that the explosion is governed by the SW mechanism at high densities. As sample ρ decreases, the completeness of the explosion increases, with the most likely mechanism for small ρ being explosive burning. The efficiency of explosive decomposition is higher for samples with lower densities.

The Nucleosynthesis of the Light Elements C to Al by Core Collapse Supernovae

We discuss the production sites of the nuclei from C to Al in solar metallicity stars in the range 13–35 M⊙. We will show how, contrary to current beliefs, the advanced burning phases and the passage of the blast wave play a pivotal role in determining the final yields of quite a few ‘light’ nuclei. We will also show how the relative contributions of the hydrostatic and explosive burning depend on the initial mass of the star: the smaller the mass the larger the importance of the explosive burning.

The First Stars

The possible nature of the first generation of stars is considered, using a star of 25M⊙ as an example. General nucleosynthesis and the production of CNO catalysts is examined in detail. The increase in neutron excess and its significance for yields from explosive burning is discussed. An estimate of the ratio of ionizing photons to heavy elements produced is derived, for use in early universe simulations.