<p>You are right. A direct collapse of a heavy star into a black hole can lead to a <a href="https://en.wikipedia.org/wiki/Failed_supernova" rel="nofollow noreferrer">failed supernova</a> without a detectable explosion.<br>
However, a black hole can also form with an SN explosion. One possibility would be the initial formation of a neutron star and bounce off of the outer layers but subsequent fall back of enough material to collapse the neutron star to a BH.<br>
In rapidly rotation stars the supernova can also be fueled by the energy released during the accretion of matter around the newly formed black hole. This would than be a <a href="http://astronomy.swin.edu.au/cosmos/H/Hypernova" rel="nofollow noreferrer">Collapsar</a>.<br>
There is also the possibility for rapidly spinning stars that a <a href="https://en.wikipedia.org/wiki/Magnetar" rel="nofollow noreferrer">magnetar</a> forms during the supernova. Here, the explosion is not primarily driven by the bounce off and the neutrino wind but by the release of magnetic energy and a subsequent spin-down of the neutron star. As the rapid rotation can stabile a NS against its collapse, this spin-down can also lead to a delayed black hole formation. Here a <a href="https://arxiv.org/pdf/1606.09316.pdf" rel="nofollow noreferrer">paper</a> about that.</p>

<p>So, SN explosions can become pretty complex and a black hole can form with and without a supernova explosion. All depending on mass, spin and metalicity of the progenitor star (&amp; whether these is a binary companion). </p>

CC BY-SA 4.0
2020-02-24T12:33:42.713Z
2020-02-24T12:33:42.713Z
SpaceCore
<p>My layman's understanding of a supernova explosion is that it's caused by a rebound when a massive star collapses. When the core collapses to a point where neutron degeneracy pressure dominates, the core collapse stops, and the matter falling in from the outer layers bounces back, causing a supernova (please correct me if I'm wrong). However, I've also read that the end result of the supernova can either be a neutron star or a black hole depending on the mass. When the star is massive enough to collapse into a black hole, what causes the supernova? What do the outer layers bounce off of? Shouldn't the whole thing just collapse into the black hole?</p>

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2020-02-24T08:26:40.747Z
There are various possibilities, depending on the star's mass, as described in https://en.wikipedia.org/wiki/Supernova#Core_collapse
PM 2Ring
<black-hole><supernova>
How does a supernova occur when a massive star collapses into a black hole?
adarsha joisa
# How does a supernova occur when a massive star collapses into a black hole?

(Asked by: username_0 on 2020-02-24)

My layman's understanding of a supernova explosion is that it's caused by a rebound when a massive star collapses. When the core collapses to a point where neutron degeneracy pressure dominates, the core collapse stops, and the matter falling in from the outer layers bounces back, causing a supernova (please correct me if I'm wrong). However, I've also read that the end result of the supernova can either be a neutron star or a black hole depending on the mass. When the star is massive enough to collapse into a black hole, what causes the supernova? What do the outer layers bounce off of? Shouldn't the whole thing just collapse into the black hole?

**Tags:** black-hole, supernova
> **Comments:**
> **username_1**: There are various possibilities, depending on the star's mass, as described in https://en.wikipedia.org/wiki/Supernova#Core_collapse  

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## 1 answers

### Answer by username_2 on 2020-02-24. Score: 3 | Accepted answer

You are right. A direct collapse of a heavy star into a black hole can lead to a [failed supernova](https://en.wikipedia.org/wiki/Failed_supernova) without a detectable explosion.  
However, a black hole can also form with an SN explosion. One possibility would be the initial formation of a neutron star and bounce off of the outer layers but subsequent fall back of enough material to collapse the neutron star to a BH.  
In rapidly rotation stars the supernova can also be fueled by the energy released during the accretion of matter around the newly formed black hole. This would than be a [Collapsar](http://astronomy.swin.edu.au/cosmos/H/Hypernova).  
There is also the possibility for rapidly spinning stars that a [magnetar](https://en.wikipedia.org/wiki/Magnetar) forms during the supernova. Here, the explosion is not primarily driven by the bounce off and the neutrino wind but by the release of magnetic energy and a subsequent spin-down of the neutron star. As the rapid rotation can stabile a NS against its collapse, this spin-down can also lead to a delayed black hole formation. Here a [paper](https://arxiv.org/pdf/1606.09316.pdf) about that.

So, SN explosions can become pretty complex and a black hole can form with and without a supernova explosion. All depending on mass, spin and metalicity of the progenitor star (& whether these is a binary companion).


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