<p>Young supernova remnant release a substantial amount of radiation as they expand into the interstellar medium. In the free expansion phase, the outgoing shock wave heats up matter to <span class="math-container">$\sim10^6$</span> Kelvin, producing thermal x-ray emission. Throughout their lives, the remnants are responsible for quite a lot of non-thermal emission, including synchrotron radiation from relativistic electrons. This synchrotron emission stretches throughout the electromagnetic spectrum, including at radio frequencies. There is, additionally, non-thermal gamma ray emission through several mechanisms, including inverse Compton scattering and hadronic interactions.</p>

<p>Supernova remnants are also thought to be one of the main sources of galactic cosmic rays. Protons are accelerated through the shock front to energies of up to a few petaelectronvolts. Cosmic ray production may be associated with gamma ray emission if there is additional dense gas for the cosmic rays to interact with.</p>

<p>This brings us to the final point of your question: yes, supernova remnants are responsible for some neutrino production. Those cosmic ray/gas interactions produce (in addition to those gamma rays) neutrinos through hadronic channels and the decays of short-lived intermediate particles, including pions and kaons. This also means that probing the gamma ray spectrum of a supernova remnant can tell us something about its neutrino spectrum.</p>

CC BY-SA 4.0
2020-05-09T17:37:27.683Z
2020-05-11T15:38:59.060Z
2020-05-11T15:38:59.060Z
HDE 226868
<p>I assume you are talking about neutron stars. Some supernovae leave nothing except a black hole, and these dense remnant objects are typically surrounded by a lot of more scattered material that was blown off before and during the supernova.</p>

<p>Neutron stars and nebulae emit a wide range of EM radiation by a number of mechanisms: straightforward thermal radiation from very hot material; synchrotron radiation from charged particles moving in very strong magnetic fields and possibly other ways.</p>

<p>In the early stages after the supernova neutrinos will be emitted from the neutron star as it cools, and from radioactive isotopes in the nebula, but both of these processes will wind down over time, probably more quickly than the EM radiation decays.</p>

CC BY-SA 4.0
2020-05-10T00:38:42.040Z
To add to what Steve said, those radioisotopes in the nebula are mainly Ni-56 which beta decays to Co-56 which beta decays to Fe-56 (which is the usual stable isotope of iron). Those beta decays release antineutrinos, and the energy from those decays is a major source of the visible afterglow of the supernova.
PM 2Ring
CC BY-SA 4.0
2020-05-09T16:45:22.190Z
2020-05-09T16:45:22.190Z
Steve Linton
<p>Do supernova remnants emit EM radiation? Moreover can neutrinos be emitted by these remnants?</p>

CC BY-SA 4.0
2020-05-09T16:26:35.570Z
Everything in the universe emits EM radiation. Neutrinos are emitted in nuclear reactions. Stellar remnants usually do not host any nuclear reactions any more.
AtmosphericPrisonEscape
CC BY-SA 4.0
2020-05-09T16:36:46.467Z
Neutrinos are not EM radiation. But look up the Crab Nebula for a famous example of a supernova reminant that emits lots of EM radiation.
adrianmcmenamin
CC BY-SA 4.0
2020-05-09T16:45:47.860Z
There are several types of supernova. Are you asking about the remnant of the core (which can be a neutron star or a black hole), or about the remnant of the outer layers that get blown off in the explosion? See https://en.wikipedia.org/wiki/Type_II_supernova
PM 2Ring
<supernova><radiation><neutrinos><cosmic-ray><stellar-remnants>
What kind of radiation do supernova remnants emit?
learner
# What kind of radiation do supernova remnants emit?

(Asked by: username_0 on 2020-05-09)

Do supernova remnants emit EM radiation? Moreover can neutrinos be emitted by these remnants?

**Tags:** supernova, radiation, neutrinos, cosmic-ray, stellar-remnants
> **Comments:**
> **username_1**: Everything in the universe emits EM radiation. Neutrinos are emitted in nuclear reactions. Stellar remnants usually do not host any nuclear reactions any more.  
> **username_2**: Neutrinos are not EM radiation. But look up the Crab Nebula for a famous example of a supernova reminant that emits lots of EM radiation.  
> **username_3**: There are several types of supernova. Are you asking about the remnant of the core (which can be a neutron star or a black hole), or about the remnant of the outer layers that get blown off in the explosion? See https://en.wikipedia.org/wiki/Type_II_supernova  

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## 2 answers

### Answer by username_4 on 2020-05-09. Score: 2

Young supernova remnant release a substantial amount of radiation as they expand into the interstellar medium. In the free expansion phase, the outgoing shock wave heats up matter to $\sim10^6$ Kelvin, producing thermal x-ray emission. Throughout their lives, the remnants are responsible for quite a lot of non-thermal emission, including synchrotron radiation from relativistic electrons. This synchrotron emission stretches throughout the electromagnetic spectrum, including at radio frequencies. There is, additionally, non-thermal gamma ray emission through several mechanisms, including inverse Compton scattering and hadronic interactions.

Supernova remnants are also thought to be one of the main sources of galactic cosmic rays. Protons are accelerated through the shock front to energies of up to a few petaelectronvolts. Cosmic ray production may be associated with gamma ray emission if there is additional dense gas for the cosmic rays to interact with.

This brings us to the final point of your question: yes, supernova remnants are responsible for some neutrino production. Those cosmic ray/gas interactions produce (in addition to those gamma rays) neutrinos through hadronic channels and the decays of short-lived intermediate particles, including pions and kaons. This also means that probing the gamma ray spectrum of a supernova remnant can tell us something about its neutrino spectrum.


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### Answer by username_5 on 2020-05-09. Score: 1

I assume you are talking about neutron stars. Some supernovae leave nothing except a black hole, and these dense remnant objects are typically surrounded by a lot of more scattered material that was blown off before and during the supernova.

Neutron stars and nebulae emit a wide range of EM radiation by a number of mechanisms: straightforward thermal radiation from very hot material; synchrotron radiation from charged particles moving in very strong magnetic fields and possibly other ways.

In the early stages after the supernova neutrinos will be emitted from the neutron star as it cools, and from radioactive isotopes in the nebula, but both of these processes will wind down over time, probably more quickly than the EM radiation decays.

> **Comments:**
> **username_3**: To add to what Steve said, those radioisotopes in the nebula are mainly Ni-56 which beta decays to Co-56 which beta decays to Fe-56 (which is the usual stable isotope of iron). Those beta decays release antineutrinos, and the energy from those decays is a major source of the visible afterglow of the supernova.  

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