Applying the Jet Feedback Mechanism to Core-Collapse Supernova Explosions

I examine a mechanism by which two fast narrow jets launched by a newly formed neutron star (NS), or a black hole (BH), at the center of a core collapse supernovae (CCSN), form two slow massive wide (SMW) jets. Such SMW jets are assumed as initial conditions in some numerical simulations that demonstrate that SMW jets can expel the rest of the collapsing star. The original fast narrow jets must deposit their energy inside the star via shock waves, and form two hot bubbles that accelerate a much larger mass to form SMW jets. To prevent the jets from penetrating through the still infalling gas and escape instead of forming the hot bubbles, the jets should encounter fresh infalling gas. This condition is met if the jets’ axis changes its direction. The exact condition is derived. In addition, to maintain a small neutrino cooling the fast narrow jets must be shocked at a distance r>1000 km from the core, such that most of the post-shock energy is in radiation, and temperature is not too high. The scenario proposed here was shown to be able to suppress star formation in newly formed galaxies, and in forming SMW jets in cooling flow clusters of galaxies and in planetary nebulae. Namely, I suggest that NSs (or BHs) at the center of CCSNs shut off their own growth and expel the rest of the mass available for accretion by the same mechanism that super-massive BHs shut off their own growth, as well as that of their host bulge, in young galaxies.

💡 Research Summary

The paper proposes a jet‑feedback mechanism (JFM) as the engine behind core‑collapse supernova (CCSN) explosions. The author argues that two fast, narrow jets launched from a newly formed neutron star (NS) or black hole (BH) at the centre of a collapsing star can, under the right conditions, deposit their kinetic energy inside the star, inflate hot bubbles, and thereby drive a much slower, more massive, and wider outflow—referred to as a slow‑massive‑wide (SMW) jet. SMW jets have been used as initial conditions in several numerical studies that successfully unbind the stellar envelope; the present work seeks to explain how such jets can be generated in the first place.

Two essential physical requirements are identified. First, the fast jets must not simply drill a hole and escape; they must continuously encounter fresh infalling material so that their energy is thermalised rather than lost to collimation. This is achieved if the jet axis changes direction on a timescale comparable to the final accretion phase (≈0.1 s), corresponding to a transverse velocity of order 10⁴–5 × 10⁴ km s⁻¹ at a radius of a few thousand kilometres. Such jitter can arise from turbulence in the infalling gas, stochastic angular‑momentum accretion, or precession of the accretion disk. Second, neutrino cooling must remain negligible. The author shows that if the jets are shocked at radii larger than ∼10³ km, the post‑shock temperature stays below ∼7 × 10⁹ K, making the neutrino loss rate ε_ν≈10²⁵ T₁₀¹⁰⁹ erg cm⁻³ s⁻¹ insignificant compared with the ∼10⁵¹ erg kinetic energy carried by the jets. This requires pre‑shock jet velocities ≲5 × 10⁴ km s⁻¹, which is compatible with the escape speed from a NS (≈0.5 c) when a substantial fraction of the jet energy is thermal.

The paper adopts a set of scaling relations drawn from earlier work on AGN feedback. The mass outflow rate in the two jets is taken to be η≈0.1 of the accretion rate onto the compact object, and the escape speed from the NS/BH is v_esc≈0.5 c. The surrounding infalling envelope at a characteristic radius r_s≈3000 km is assumed to have a density ρ_s≈10⁶ g cm⁻³, yielding an inflow rate of order 1 M_⊙ s⁻¹. With these numbers the jet power (∼η Ṁ_acc v_esc²/2) is sufficient to accelerate the envelope to ∼10⁴ km s⁻¹ and to supply the canonical explosion energy of 10⁵¹ erg.

The author reviews observational evidence for SMW jets in various astrophysical contexts—AGN outflows, cooling‑flow clusters, and planetary nebulae—and notes that in all cases the jets are not launched directly from the accretion disk but are secondary outflows powered by the primary fast jets. By applying the same feedback physics to CCSNe, the paper suggests a unified picture: the central compact object self‑regulates its growth and simultaneously ejects the remaining stellar mass, analogous to how super‑massive black holes regulate galaxy bulge growth.

The paper also discusses prior CCSN simulations that injected jets at radii of 300–4000 km. Those studies found that when the injected jets carried a large thermal component they behaved effectively as SMW jets, supporting the present scenario. Conversely, simulations with strictly collimated, constant‑direction jets failed to unbind the envelope, underscoring the importance of jet jitter and wide‑angle expansion.

In summary, the work derives analytic criteria for (i) jet axis jitter (transverse velocity ≳10⁴ km s⁻¹), (ii) shock radius r_shock > 10³ km, (iii) post‑shock temperature T ≲ 7 × 10⁹ K (neutrino cooling negligible), and (iv) mass‑loading ratio η ≈ 0.1. When these conditions are satisfied, the fast narrow jets are thermalised, inflate bubbles, and drive SMW outflows that can explode the star. The author emphasizes that this jet‑feedback mechanism offers a compelling alternative to traditional neutrino‑driven explosion models, and calls for high‑resolution 3‑D simulations to test the proposed jitter, disk formation, and feedback efficiency in realistic CCSN environments.