From Choked to Successful: The Role of Black Hole Spin in Collapsar Jet Breakout

Abstract

Long gamma-ray bursts (LGRBs) are believed to originate from the core collapse of massive Wolf-Rayet (WR) stars, leading to the formation of a spinning black hole that powers a relativistic jet. The prompt emission is produced once the jet emerges from the stellar envelope. We perform 2D axisymmetric RHD simulations using the PLUTO code to model semi-self-consistent, accretion-powered jets launched by Kerr black holes. For the two progenitor models, we adopt black hole masses of $4M_{\odot }$ and $5M_{\odot }$ corresponding to WR stars of $10M_{\odot }$ and $25M_{\odot }$, respectively. Unlike previous studies, our simulations employ continuous jet injection, with the injected power linked to black hole spin and accretion through an empirical relation motivated by GRMHD simulations, enabling a controlled exploration of jet energetics over $10^{48}$-$10^{52}\mathrm{erg}{\mathrm{s}}^{-1}$. We investigate jet breakout for WR progenitors of $10M_{\odot }$ and $25M_{\odot }$ and identify a critical spin threshold: jets are choked for $a\le 0.001$ and successfully break out for $a>0.001$. The breakout time ($t_B$) shows a correlation with jet luminosity ($L_{\mathrm{jet}}$) and spin ($a$), revealing three regimes: Newtonian ($a\lesssim 0.03$), relativistic ($a\gtrsim 0.3$), and intermediate. A dichotomy is observed in jet head velocity at breakout, with ${\beta }_h\gtrsim 0.8$ for high-spin and ${\beta }_h\sim 0.35$-$0.8$ for lower spins. In the Newtonian regime, simulations yield $t_B\propto L_{\mathrm{jet}}^{-0.48}$, steeper than analytical predictions, with systematically longer breakout times indicating modified jet-head scaling. In the relativistic regime, calibrated analytical models show improved agreement, with simulations indicating efficient jet propagation.

arXiv comment20 pages, 11 figures, Submitted. Comments and suggestions are welcome