The tunneling effect can also explain the mysterious spherical kilonova.

When neutrons are impacting, that causes an effect called neutron fusion.  

It's possible that when high-speed neutrons impact. When another neutron's north pole is against another neutron's south pole. That causes an impact even if the speed of those particles would be low. But those particles' impact speed in colliding neutron stars is very high. In some models impacting neutron stars form neutron vapor when their interaction pulls particles off their shells. 

The impact speed of those neutrons is high. That thing turns them into energy. That kind of neutron fusion is possible in high energy and strong gravitational environment. That means the impacting neutrons between neutron stars could form the spherical energy impulse. 

When neutron stars collide they turn the opposite poles against each other. That thing causes an extremely strong electromagnetic effect. That effect loads energy to neutrons that are starting to act like ions. Neutrons with a high energy load make it possible. Neutrons start to act like ions. Three quarks are forming neutrons. 

And when the neutron's energy level starts to rise the tip quark collects energy. Then two other quarks transmit energy to the neutron's sides. That thing makes it possible. That a neutron can push another neutron away from its route. 

The neutrons can tunnel through material like ions. And when they stop they are sending energy impulses. So if the tunneling neutrons stopped just in the middle of the neutron star. That could form the mystery spherical energy impulse from kilonova. 

In some models, when neutron stars collide. Those neutron stars are forming liquid. There is a layer of neutron liquid under the shell of the neutron star. The thickness of that material depends on gravity. So in high-mass neutron stars that material is extremely thick. And that makes the neutron star's shell's speed in comparison with its nucleus lower than low-mass neutron stars. And the name of those things is magnetars. 

If the neutron star has a very low mass. There is a possibility that the neutron fluid is like gas between the nucleus and its shell. That allows the small-mass neutron star's shell rotates at a very high speed if we compare that with the rotating speed of the nucleus. That makes its magnetic field very strong. 

And that makes low-mass neutron stars objects called magnetars. There is the possibility that some magnetar's shell hovers above neutron gas. And that can form the most powerful magnetic fields in the universe. 

When that kind of neutron star or magnetar faces another neutron star that breaks its shell. The neutron fluid or neutron gas travels to heavier neutron stars. Because the electromagnetic energy level in bigger neutron stars rises, that causes a situation the distance between neutrons increases. 

And that creates a situation in that neutrons can tunnel through the neutron structure. When those neutrons stop in the middle of the neutron stars they send radiation. That means neutrons have a similar form as ions. 

https://www.sciencealert.com/colliding-neutron-stars-created-a-sphere-so-perfect-its-shocked-physicists

https://scitechdaily.com/astrophysicists-discover-a-mysterious-perfect-explosion-in-space-it-makes-no-sense/

https://shorttextsofoldscholars.blogspot.com/