Long-lived intermittent accretion disks in the jittering jets explosion mechanism (JJEM) of core-collapse supernovae

The Cosmic Fireworks Show

Imagine the universe as a grand, chaotic construction site where massive stars are the buildings. When these stellar giants run out of fuel, they don't just fade away; they collapse in on themselves and then explode with the force of a billion suns. This event is called a core-collapse supernova. For decades, astronomers have been trying to figure out exactly how these explosions happen. It's like trying to understand how a shaken soda bottle pops its cap off: is it the gas pressure inside, or is it something else?

Two main ideas have been fighting for the spotlight. One theory suggests that invisible ghost particles called neutrinos act like a blowtorch, heating the star's core until it blows apart. The other idea, which this paper explores, is the "Jittering Jets Explosion Mechanism" (JJEM). Think of this as a cosmic sprinkler system. Instead of a steady stream, imagine a sprinkler that spins wildly, shooting out pairs of water jets in random directions. In this scenario, the explosion is driven by these high-speed jets of gas shooting out from the newborn, ultra-dense core (a neutron star). The big mystery has been: how do these sprinklers keep shooting long enough and hard enough to blow up the whole star, especially when the star's core is spinning in all sorts of messy, unpredictable ways?

The Puzzle of the Long-Lasting Sprinklers

In this study, astrophysicist Noam Soker investigates a specific puzzle found in the "scars" left behind by these explosions, known as supernova remnants. When astronomers look at the debris of some exploded stars, they see a very specific pattern: just one, two, or three pairs of incredibly powerful jets that seem to have done most of the heavy lifting. This is strange because the standard model of the JJEM suggests that the chaotic spinning of the star's core should create a chaotic mess of many small, short-lived jet pairs—perhaps 5 to 20 pairs—rather than just a few massive ones.

The paper asks a simple question: How can a jet-launching disk survive long enough to fire just a few, super-energetic pairs of jets, instead of fizzling out after a split second? The author suggests that the answer lies in a clever feedback loop where the jets themselves help keep the party going.

The Three Tricks of the Trade

Soker proposes three mechanisms that work together to turn a short-lived jet burst into a long-lived, powerful explosion.

1. The "Polar Blockade" (The Bubbles)
Imagine the newborn neutron star as a spinning top that shoots out two jets of gas, one up and one down. As these jets blast into the surrounding star material, they inflate giant bubbles, like blowing soap bubbles. These bubbles act as a shield, blocking new material from falling in from the top and bottom (the polar directions). Because the jets are busy blocking the poles, the only place left for new gas to fall in is from the sides—the equatorial plane. This forces all the incoming material to swirl around the disk in the same direction as the jets, feeding the fire instead of smothering it. This is a positive feedback loop: the jets block the wrong way, forcing more fuel into the right way.

2. The "Angular Momentum Shuffle" (The Viscous Handoff)
Here is where the physics gets a bit like a game of musical chairs. Usually, if a spinning disk starts getting fed with material that has no spin (zero angular momentum), the disk should slow down and collapse. However, Soker shows that the "stickiness" (viscosity) inside the disk acts like a conveyor belt. It can take the spin from the inner parts of the disk and push it outward. Even if new, non-spinning material is added, the disk can rearrange its internal spin so that the inner part keeps spinning fast enough to launch jets for a longer time. The paper calculates that this process can extend the disk's life to about its "viscous timescale," which is roughly 0.01 to 0.1 seconds. While that sounds short, in the world of exploding stars, it's an eternity.

3. The "Random Walk" (The Lucky Coin Flip)
Finally, there is the element of chance. The material falling into the star doesn't have a perfect, steady spin; it fluctuates wildly, sometimes spinning left, sometimes right. Soker suggests that sometimes, by pure luck, these random fluctuations might all add up in the same direction as the original jets. It's like flipping a coin many times; occasionally, you might get a streak of heads. If the random "walk" of the spinning gas happens to align with the existing disk, it gives the disk an extra boost, allowing it to survive longer and launch those massive, energetic jets we see in the remnants.

What This Means for the Universe

The paper doesn't claim to have run a supercomputer simulation that proves this happens every time. Instead, it uses mathematical models and observations of supernova remnants (like the Crab Nebula and others) to suggest that these three effects—blocking the poles, shuffling the spin, and lucky random fluctuations—can work together.

The author argues that this explains why we see some supernova remnants dominated by just a few, very powerful jet pairs, while others show a chaotic mess of many smaller ones. It strengthens the case that the "Jittering Jets" mechanism is the primary way these stars explode, rather than the neutrino-heating theory. The paper suggests that while the neutrino theory struggles to explain the energy of these explosions, the jittering jets, aided by these long-lived disks, can do the job.

In short, the paper paints a picture of a cosmic explosion where the jets don't just shoot out and die; they build a shield, shuffle their energy, and get lucky with the wind, allowing them to keep blasting away until the star is completely blown apart. Future, more detailed computer simulations will need to test if these three tricks really work together in the chaotic reality of a dying star, but for now, the math and the telescope data point to a very dynamic, jet-powered universe.