On the outflows driven by choked jets

Many stripped-envelope supernovae (SNe) present a signature of high-velocity material responsible for broad absorption lines in the observed spectrum. These include SNe associated with long gamma-ray bursts (LGRBs), low-luminosity GRBs (llGRBs), and SNe not associated with GRBs. It was recently suggested that this high-velocity material originates from a cocoon driven by a relativistic jet. In LGRBs, this jet breaks out successfully from the stellar envelope, while the jet is choked in llGRBs and SNe that are not associated with GRBs. Here, we use numerical simulations to explore the velocity distribution of an outflow driven by a choked jet and its dependence on the jet and progenitor properties. We find that in all cases where the jet is not choked too deep within the star, the outflow carries a roughly constant amount of energy per logarithmic scale of proper velocity over a wide range of velocities, which depends mostly on the cocoon volume at the time of its breakout. This is a universal property of jet-driven outflows, which does not exist in outflows of spherically symmetric explosions or when the jets are choked very deep within the star. We, therefore, conclude that choked jets (not too deep) provide a natural explanation for the fast material seen in the early spectra of stripped-envelope SNe that are not associated with LGRBs and that properties of this material could reveal information on the otherwise hidden jets. 127 Collisionless relaxation of galaxy clusters and the dark wave (if it exists). ENEA National Laboratory, Centro Ricerche Frascati, Frascati, Italy This paper reports a stochastic theory of gravitational relaxation based on a Lévy-fractional Klein- Kramers equation with self-consistent entropy term. The use of fractional derivatives in this equation is motivated with nonequilibrium phase-space dynamics breaking the restrictive assumptions of Gaussianity, lack of correlation and nearness to virialized state. Astrophysical applications of the theory concern gravitational evolution of galaxy clusters with non-minimally coupled cold dark matter. One hard result pertaining to the statistical model is that position correlations between galaxies are attracted by the power law r^{-7/4}, which approximates the canonical scaling r^{-1.8} found in observations. The kinetic description, considered in this paper’s work, is compatible with an idea that the relaxation of galaxy clusters to virialized state could be collisionless and mediated by hypothetical “dark waves”, collective excitations of the coupled baryonic-dark matter system driven by the variation of local curvature on suitably small spatial scales. Reference: A. V. Milovanov, Stochastic theory of gravitational relaxation and Lévy-fractional Klein-Kramers equation, Europhys. Lett. EPL 140 (2022) 59001.