New class of high-energy transients from crashes of supernova ejecta with massive circumstellar material shells

Abstract

A new class of core-collapse supernovae (SNe) has been discovered in recent years by optical/infrared surveys; these SNe suggest the presence of one or more extremely dense (∼ 10 5−11 cm −3 ) shells of circumstellar material (CSM) on 10 2−4 AU scales. We consider the collisions of the SN ejecta with these massive CSM shells as potential cosmic-ray (CR) accelerators. If ∼ 10% of the SN energy goes into CRs, multi-TeV neutrinos and/or GeV-TeV gamma rays almost simultaneous with the optical/infrared light curves are detectable for SNe at 20−30 Mpc. A new type of coordinated multi-messenger search for such transients of duration ∼ 1 − 10 months is required; these may give important clues to the physical origin of such SNe and to CR acceleration mechanisms.

On the origin of high-energy cosmic neutrinos

“…Thanks to their high gas densities, f pp can be quite high and the observed neutrino flux level can be well explained as long as CRs can be accelerated above 100 PeV energies [28,29,23,14,30]. However, ordinary supernova remnants are not able to accelerate CRs up to this energy, so a lot of speculations have recently been made, including supermassive black hole activities [14], galaxy mergers [31], super bubbles, interaction-powered supernovae [32], hypernovae [33,34,23,35], transrelativistic supernovae and GRBs [36,37,38,39,40]. But it is highly unclear whether different populations lead to a smooth power-law spectrum and why the energy budget of rare transients is almost comparable to that of ordinary supernovae [23].…”

TeV–PeV Neutrinos from Low-Power Gamma-Ray Burst Jets inside Stars

“…For l dec ≪ l u , since significant deceleration occurs over ∼ l dec , including the immediate upstream [28,29], CRs with r u L ≪ l dec do not feel the strong compression and the shock acceleration will be suppressed [27,33,34]. CRs are expected when photons readily escape from the system and the shock becomes radiation unmediated, which occurs when l u l dec [30,36]. Regarding this as a reasonably necessary condition for the CR acceleration, we have…”

“…LL GRBs can give ∼ 10 −8 GeV cm −2 s −1 sr −1 , as predicted in Refs. [6,7,30]. They are distinct from classical GRBs and they may be more baryon rich [46].…”

“…1), one no longer expects a strong shock jump (although a weak subshock may exist [29]), unlike the usual collisionless shock, and the shock width is determined by the deceleration scale l dec ≈ (n u σ T y ± ) −1 ≃ 1.5 × 10 5 cm n −1 u,19 y −1 ± when the comoving size of the upstream flow l u is longer than l dec . Here n u is the upstream proton density, and y ± (≥ 1) is the possible effect of pairs entrained or produced by the shock [30].…”

Astrophysical origin of high-energy cosmic neutrinos

“…Thanks to their high gas densities, f pp can be quite high and the observed neutrino flux level can be well explained as long as CRs can be accelerated above 100 PeV energies [10,21,[26][27][28]. However, ordinary supernova remnants are not able to accelerate CRs up to this energy, so a lot of speculations have recently been made, including super-massive black hole activities [10], galaxy mergers [29], super bubbles, interaction-powered supernovae [30], hypernovae [21,[31][32][33], transrelativistic supernovae and GRBs [34][35][36][37][38]. But it is highly unclear whether different populations lead to a smooth power-law spectrum and why the energy budget of rare transients is almost comparable to that of ordinary supernovae [21].…”