Supernova hosts for gamma-ray burst jets: dynamical constraints

Abstract

I constrain a possible supernova origin for gamma‐ray bursts (GRBs) by modelling the dynamical interaction between a relativistic jet and a stellar envelope surrounding it. The delay in observer time introduced by the jet traversing the envelope should not be long compared with the duration of gamma‐ray emission; also, the jet should not be swallowed by the spherical explosion it powers. The only stellar progenitors that comfortably satisfy these constraints, if one assumes that jets move ballistically within their host stars, are compact carbon–oxygen or helium post‐Wolf–Rayet stars (type Ic or Ib supernovae); type II supernovae are ruled out. Notably, very massive stars do not appear to be capable of producing the observed bursts at any redshift unless the stellar envelope is stripped prior to collapse. The presence of a dense stellar wind places an upper limit on the Lorentz factor of the jet in the internal shock model; however, this constraint may be evaded if the wind is swept forward by a photon precursor. Shock breakout and cocoon blowout are considered individually; neither presents a likely source of precursors for cosmological GRBs. These envelope constraints could conceivably be circumvented if jets are laterally pressure‐confined while traversing the outer stellar envelope. If so, jets responsible for observed GRBs must have been launched from a region several hundred kilometres wide, have been crossed by strong shocks, or have mixed with envelope material as they travel. A phase of pressure confinement and mixing would imprint correlations among jets that may explain observed GRB variability–luminosity and lag–luminosity correlations.

On the composition of GRBs’ Collapsar jets

“…Hydrodynamic jet propagation within stellar envelopes was studied both analytically (Mészáros & Waxman, 2001;Matzner, 2003;Lazzati & Begelman, 2005; and numerically (MacFadyen & Woosley, 1999;Aloy et al, 2000;MacFadyen, Woosley & Heger, 2001;Zhang, Woosley, & MacFadyen, 2003;Lazzati & Begelman, 2005;Morsony, Lazzati, & Begelman, 2007;Mizuta & Aloy, 2009;Mizuta & Ioka, 2013), while the propagation of a magnetic jet in stars was discussed in (Proga et al, 2003;Uzdensky & MacFadyen, 2007;Bucciantini et al, 2009;Levinson & Begelman, 2013;Bromberg & Tchekhovskoy, in prep). These works show that as long as the jet does not breach out of the star it dissipates most of the energy that reaches its head.…”

Population III Gamma-Ray Burst

“…The shocked jet and shocked envelope go sideways and become the cocoon component (Matzner 2003. Figure 2 shows our results.…”

“…Especially for Pop III stars, the mass accretion continues during the main sequence phase, so that the chemically homogeneous evolution induced by rapid rotation might not work (Ohkubo et al 2009). Their extended envelopes may suppress the emergence of relativistic jets out of their surface even if such jets were produced (Matzner 2003). The observed burst duration T ∼ 100 s, providing an estimate for the lifetime of the central engine, suggests that the jet can only travel a distance of ∼ cT ∼ 10 12 cm before being slowed down to a nonrelativistic speed.…”

Magnetars and Gamma Ray Bursts

“…We know that, as the outflow emerges from the interior of the host star, it collimates into a jet that punches through the stellar envelope, creating a channel where material coming from the central engine can flow (e.g., Matzner 2003). Afterglow observations (jet breaks; Rhoads 1999) and GRB energetics (comparison of the total energy derived from late radio afterglow observations with respect to the prompt emission) confirm that a collimated flow is present.…”