The signal produced in neutrino observatories by the pair-annihilation neutrinos emitted from a 20 M pre-supernova star at the silicon burning phase is estimated. The spectrum of the neutrinos with an average energy ∼2 MeV is calculated with the use of the Monte Carlo method. A few relevant reactions for neutrinos and anti-neutrinos in modern detectors are considered. The most promising results are fromν e + p −→ n + e + reaction. During the Si-burning phase we expect 1.38 neutrons/day/kiloton of water to be produced by neutrinos from a star located at a distance of 1 kpc. Small admixture of effective neutron-adsorbers as e.g. NaCl or GdCl 3 makes these neutrons easily visible because of Cherenkov light produced by electrons which were hit by ∼8 MeV photon cascade emitted by Cl or Gd nuclei. The estimated rate of neutron production for SNO and Super-Kamiokande is, respectively, 2.4 and 44 events per day for a star at 1 kpc. For future detectors UNO and Hyper-Kamiokande we expect 6.1 and 7.5 events per day even for a star 10 kpc away. This would make it possible to foresee a massive star death a few days before its core collapse. Importance of such a detection for theoretical astrophysics is discussed.

We study the evolution of the collapsing core of a 15 M blue supergiant supernova progenitor from the core bounce until 1.5 seconds later. We present a sample of hydrodynamic models parameterized to match the explosion energetics of SN 1987A.We find the spatial model dimensionality to be an important contributing factor in the explosion process. Compared to two-dimensional simulations, our three-dimensional models require lower neutrino luminosities to produce equally energetic explosions. We estimate that the convective engine in our models is 4% more efficient in three dimensions than in two dimensions. We propose that the greater efficiency of the convective engine found in three-dimensional simulations might be due to the larger surface-to-volume ratio of convective plumes, which aids in distributing energy deposited by neutrinos.We do not find evidence of the standing accretion shock instability nor turbulence being a key factor in powering the explosion in our models. Instead, the analysis of the energy transport in the post-shock region reveals characteristics of penetrative convection. The explosion energy decreases dramatically once the resolution is inadequate to capture the morphology of convection on large scales. This shows that the role of dimensionality is secondary to correctly accounting for the basic physics of the explosion.We also analyze information provided by particle tracers embedded in the flow, and find that the unbound material has relatively long residency times in two-dimensional models, while in three dimensions a significant fraction of the explosion energy is carried by particles with relatively short residency times.

We integrate numerically axially symmetric stationary Einstein equations describing selfgravitating disks around spinless black holes. The numerical scheme is based on a method developed by Shibata, but contains important new ingredients. We derive a new general-relativistic Keplerian rotation law for self-gravitating disks around spinning black holes. Former results concerning rotation around spinless black holes emerge in the limit of a vanishing spin parameter. These rotation curves might be used for the description of rotating stars, after appropriate modification around the symmetry axis. They can be applied to the description of compact torus-black hole configurations, including active galactic nuclei or products of coalescences of two neutron stars.

Although the existence of dark matter is supported by many evidences, based on astrophysical measurements, its nature is still completely unknown. One major candidate is represented by weakly interacting massive particles (WIMPs), which could in principle be detected through their collisions with ordinary nuclei in a sensitive target, producing observable low-energy (<100 keV) nuclear recoils. The DarkSide program aims at the WIPMs detection using a liquid argon time projection chamber (LAr-TPC). In this paper we quickly review the DarkSide program focusing in particular on the next generation experiment DarkSide-G2, a 3.6-ton LAr-TPC. The different detector components are described as well as the improvements needed to scale the detector from DarkSide-50 (50 kg LAr-TPC) up to DarkSide-G2. Finally, the preliminary results on background suppression and expected sensitivity are presented.