Relativistic Jets in Core-collapse Supernovae

Abstract

After several decades of extensive research the mechanism driving core-collapse supernovae (CCSNe) is still unclear. A common mechanism is a neutrino driven outflow, but others have been proposed. Among those, a long-standing idea is that jets play an important role in SN explosions. Gamma-ray bursts (GRBs) that accompany rare and powerful CCSNe, sometimes called "hypernovae", provide a clear evidence for a jet activity. The relativistic GRB jet punches a hole in the stellar envelope and produces the observed gamma-rays far outside the progenitor star. While SNe and jets coexist in long GRBs, the relation between the mechanisms driving the hypernova and the jet is unknown. Also unclear is the relation between the rare hypernovae and the more common CCSNe. Here we present observational evidence that indicates that choked jets are active in CCSNe types that are not associated with GRBs. A choked jet deposits all its energy in a cocoon. The cocoon eventually breaks out from the star releasing energetic material at very high, yet sub-relativistic, velocities. This fast moving material has a unique signature that can be detected in early time SN spectra. We find a clear evidence for this signature in several CC-SNe, all involving progenitors that have lost all, or most, of their hydrogen envelope prior to the explosion. These include CCSNe that don't harbor GRBs or any other relativistic outflows. Our findings suggest a continuum of central engine activities in different types of CCSNe and call for rethinking of the explosion mechanism of regular CCSNe.Massive stars end their lives in supernova (SN) explosions releasing typically ∼ 10 51 ergs (sometimes called FOE or Bethe) in kinetic energy and a fraction of that in a visible light. 1 arXiv:1704.08298v2 [astro-ph.HE] 2 Jun 2017As the star consumes its energy reservoir its core collapses (hence Core Collapse Supernova -CCSNe) and becomes a compact object. A shock wave that propagates outwards ejects the envelope and synthesizes radioactive 56 Ni that powers part of the visible SN light. So far, in addition to the explosions themselves, we have seen the massive stellar progenitors, neutrinos produced by the newborn neutron star, the compact objects left behind (typically a neutron star) and the expanding matter, (the supernova remnant). All these observations confirm the general picture outline by Baade and Zwicky already in the 1930's [1]. However, while the basic picture is well understood, in spite of several decades of research, the mechanism(s) powering the shocks that drive the SNe is not clear. Models suggested (see e.g.[2] and references therein) include neutrino heating, magnetohydrodynamic, thermonuclear, bounce-shock, acoustic and phase transition mechanisms. The neutrino driven explosion, possibly in combination with hydrodynamic non-spherical instabilities and non-radial flows, is the current favorite (at least for most common core collapses, type II SNe), while others (e.g., bounce-shock) seems highly unlikely. In spite of the importance of 3D effects, th...

Constraining the fraction of core-collapse supernovae harbouring choked jets with high-energy neutrinos

“…For LSST we assume a magnitude limit of R∼24 for a typical exposure of 2 × 15 s (Abell et al 2009). After assuming an absolute magnitude at maximum for CCSNe of is M= -17.5 (Patat et al 1994)), we find that they can be detected out to r ∼ 200 Mpc with ZTF, and out to r ∼ 1.5 Gpc with LSST.…”

“…The mechanism driving core-collapse supernova (CCSN) explosions is still unclear. A common explanation is neutrino driven outflows (Colgate & Petschek 1982), however a recent idea is that jets could play an important role in SN explosions (Piran et al 2019). CCSNe associated with long duration gamma-ray bursts (GRBs), sometimes called Hypernovae, provide a clear evidence for strongly aspherical explosions (Maeda et al 2008), suggesting a jet-like activity.…”

“…CCSNe associated with long duration gamma-ray bursts (GRBs), sometimes called Hypernovae, provide a clear evidence for strongly aspherical explosions (Maeda et al 2008), suggesting a jet-like activity. Piran et al (2019) proposed that a similar mechanism might be active also in "standard" CCSNe types not associated with GRBs. Such a scenario is suggested by observations indicating energy deposition by so called "choked" jets in a cocoon within the stellar envelope.…”

“…However, whether or not CCSNe that do not harbor GRBs might be powered by jet/cocoons activity is still a matter of active discussion within the community. The most natural interpretation of the energetic fast moving component observed in the early spectra of the supernovae by Piran et al 2019, is that this is the cocoons matter that breaks out from the progenitor. In a few cases such as SN 2008D/GRB 080109 , SN 2006aj/GRB 060218 (Campana et al 2006) and GRB 171205A/2017iuk (Izzo et al 2019) we might have even seen the direct thermal emission of this hot cocoon material.…”

The propagation of choked jet outflows in power-law external media

“…Interestingly, although they are more difficult to observe, llGRBs may be more common per cosmic volume than standard GRBs (Soderberg et al 2006), again hinting that choked jets may be common. Third, early spectroscopy of Type Ib and Ic supernovae (SNe) has unveiled a distinct high-velocity component in several cases (e.g., Piran et al 2019;Izzo et al 2019). The inferred energy (∼ 10 51 erg s −1 ) and velocity (∼ 0.1c) of this component are consistent with the expectations for a GRB jet's cocoon.…”