Editing Supernova (section)

===Energy output===
[[Image:SNIacurva.png|thumb|The radioactive decays of nickel-56 and cobalt-56 that produce a supernova visible light curve<ref name="explosion_model"/><ref name="mazzali"/>]]
Although supernovae are primarily known as luminous events, the [[electromagnetic radiation]] they release is almost a minor side-effect. Particularly in the case of core collapse supernovae, the emitted electromagnetic radiation is a tiny fraction of the total energy released during the event.<ref>{{cite journal |doi=10.1126/science.1075935 |title=The Secrets Behind Supernovae |year=2002 |last1=Janka |first1=H.-Th. |journal=Science |volume=297 |issue=5584 |pages=1134–1135 |pmid=12183617 |s2cid=34349443 }}</ref>

There is a fundamental difference between the balance of energy production in the different types of supernova. In type Ia white dwarf detonations, most of the energy is directed into [[nucleosynthesis|heavy element synthesis]] and the [[kinetic energy]] of the ejecta.<ref>{{cite journal |doi=10.1126/science.276.5317.1378|title=Type Ia Supernovae: Their Origin and Possible Applications in Cosmology |year=1997 |last1=Nomoto |first1=Ken'Ichi |last2=Iwamoto |first2=Koichi |last3=Kishimoto |first3=Nobuhiro |journal=Science |volume=276 |issue=5317 |pages=1378–1382 |pmid=9190677 |arxiv=astro-ph/9706007 |bibcode=1997Sci...276.1378N |s2cid=2502919 }}</ref> In core collapse supernovae, the vast majority of the energy is directed into [[supernova neutrino|neutrino]] emission, and while some of this apparently powers the observed destruction, 99%+ of the neutrinos escape the star in the first few minutes following the start of the collapse.<ref name="Antonioli-2004"/>

Standard type Ia supernovae derive their energy from a runaway nuclear fusion of a carbon-oxygen white dwarf. The details of the energetics are still not fully understood, but the result is the ejection of the entire mass of the original star at high kinetic energy. Around half a solar mass of that mass is [[nickel-56|<sup>56</sup>Ni]] generated from [[Silicon-burning process|silicon burning]]. <sup>56</sup>Ni is [[radioactive]] and decays into [[cobalt-56|<sup>56</sup>Co]] by [[beta plus decay]] (with a [[half life]] of six days) and gamma rays. <sup>56</sup>Co itself decays by the beta plus ([[positron]]) path with a half life of 77 days into stable <sup>56</sup>Fe. These two processes are responsible for the electromagnetic radiation from type Ia supernovae. In combination with the changing transparency of the ejected material, they produce the rapidly declining light curve.<ref name="mazzali"/>

Core collapse supernovae are on average visually fainter than type Ia supernovae,<ref name="Springer-2016"/><ref name="Modjaz-2019"/><ref name="Nyholm-2020"/> but the total energy released is far higher, as outlined in the following table.

{|class="wikitable"
|+Energetics of supernovae
!Supernova !!Approximate total energy<br/>x10<sup>44</sup> joules ([[Foe (unit)|foe]]){{ref|c|c}} !!Ejected Ni<br/>(solar masses) !!Neutrino energy<br/>(foe) !!Kinetic energy<br/>(foe) !!Electromagnetic radiation<br/>(foe)
|-
|Type Ia<ref name="mazzali">{{Cite journal
 |last1=Mazzali
 |first1=P. A.
 |last2=Nomoto
 |first2=K. I.
 |last3=Cappellaro
 |first3=E.
 |last4=Nakamura
 |first4=T.
 |last5=Umeda
 |first5=H.
 |last6=Iwamoto
 |first6=K.
 |year=2001
 |title=Can Differences in the Nickel Abundance in Chandrasekhar-Mass Models Explain the Relation between the Brightness and Decline Rate of Normal Type Ia Supernovae?
 |journal=The Astrophysical Journal
 |volume=547
 |issue=2
 |pages=988
 |arxiv=astro-ph/0009490
 |bibcode=2001ApJ...547..988M
 |doi=10.1086/318428 |doi-access=free
 |s2cid=9324294
 }}</ref><ref>
{{Cite journal
 |last1=Iwamoto |first1=K.
 |year=2006
 |title=Neutrino Emission from Type Ia Supernovae
 |journal=AIP Conference Proceedings
 |volume=847 |pages=406–408
 |doi=10.1063/1.2234440
|bibcode=2006AIPC..847..406I
 }}</ref><ref>
{{Cite journal
 |last1=Hayden |first1=B. T.
 |last2=Garnavich |first2=P. M.
 |last3=Kessler |first3=R.
 |last4=Frieman |first4=J. A.
 |last5=Jha |first5=S. W.
 |last6=Bassett |first6=B.
 |last7=Cinabro |first7=D.
 |last8=Dilday |first8=B.
 |last9=Kasen |first9=D.
 |last10=Marriner |first10=J.
 |last11=Nichol |first11=R. C.
 |last12=Riess |first12=A. G.
 |last13=Sako |first13=M.
 |last14=Schneider |first14=D. P.
 |last15=Smith |first15=M.
 |last16=Sollerman |first16=J.
 |year=2010
 |title=The Rise and Fall of Type Ia Supernova Light Curves in the SDSS-II Supernova Survey
 |journal=The Astrophysical Journal
 |volume=712 |issue=1 |pages=350–366
 |arxiv=1001.3428
 |bibcode=2010ApJ...712..350H
 |doi=10.1088/0004-637X/712/1/350
|s2cid=118463541
 }}</ref> ||style="text-align:right"|1.5 ||style="text-align:right"|0.4 – 0.8 ||style="text-align:right"|0.1 ||style="text-align:right"|1.3 – 1.4 ||style="text-align:right"|~0.01
|-
|Core collapse<ref>
{{cite journal
 |last1=Janka |first1=H.-T.
 |year=2012
 |title=Explosion Mechanisms of Core-Collapse Supernovae
 |journal=[[Annual Review of Nuclear and Particle Science]]
 |volume=62 |issue=1 |pages=407–451
 |arxiv=1206.2503
 |bibcode=2012ARNPS..62..407J
 |doi=10.1146/annurev-nucl-102711-094901|doi-access=free
|s2cid=118417333
 }}</ref><ref>
{{cite journal
 |last1=Smartt |first1=Stephen J.
 |last2=Nomoto |first2=Ken'ichi
 |last3=Cappellaro |first3=Enrico
 |last4=Nakamura |first4=Takayoshi
 |last5=Umeda |first5=Hideyuki
 |last6=Iwamoto |first6=Koichi
 |date=2009
 |title=Progenitors of core-collapse supernovae
 |journal=[[Annual Review of Astronomy and Astrophysics]]
 |volume=47 |issue=1 |pages=63–106
 |arxiv=0908.0700
 |bibcode=2009ARA&A..47...63S
 |doi=10.1146/annurev-astro-082708-101737
|s2cid=55900386
 }}</ref> ||style="text-align:right"|100 ||style="text-align:right"|(0.01) – 1 ||style="text-align:right"|100 ||style="text-align:right"|1 ||style="text-align:right"|0.001 – 0.01
|-
|Hypernova ||style="text-align:right"|100 ||style="text-align:right"|~1 ||style="text-align:right"|1–100 ||style="text-align:right"|1–100 ||style="text-align:right"|~0.1
|-
|Pair instability<ref name=kasen/> ||style="text-align:right"|5–100 ||style="text-align:right"|0.5 – 50 ||style="text-align:right"|low? ||style="text-align:right"|1–100 ||style="text-align:right"|0.01 – 0.1
|}

In some core collapse supernovae, fallback onto a black hole drives [[relativistic jet]]s which may produce a brief energetic and directional burst of gamma rays and also transfers substantial further energy into the ejected material. This is one scenario for producing high-luminosity supernovae and is thought to be the cause of type Ic hypernovae and long-duration gamma-ray bursts.<ref>{{Cite journal |last1=Dessart |first1=L. |last2=Burrows |first2=A. |last3=Livne |first3=E. |last4=Ott |first4=C. D. |date=20 January 2008 |title=The Proto-Neutron Star Phase of the Collapsar Model and the Route to Long-Soft Gamma-Ray Bursts and Hypernovae |doi-access=free |journal=The Astrophysical Journal |language=en |volume=673 |issue=1 |pages=L43–L46 |bibcode=2008ApJ...673L..43D |arxiv=0710.5789 |doi=10.1086/527519 |issn=0004-637X}}</ref> If the relativistic jets are too brief and fail to penetrate the stellar envelope then a low-luminosity gamma-ray burst may be produced and the supernova may be sub-luminous.<ref>{{Cite journal |last1=Senno |first1=Nicholas |last2=Murase |first2=Kohta |last3=Mészáros |first3=Peter |date=8 April 2016 |title=Choked jets and low-luminosity gamma-ray bursts as hidden neutrino sources |url=https://link.aps.org/doi/10.1103/PhysRevD.93.083003 |journal=Physical Review D |language=en |volume=93 |issue=8 |pages=083003 |doi=10.1103/PhysRevD.93.083003 |bibcode=2016PhRvD..93h3003S |arxiv=1512.08513 |s2cid=16452722 |issn=2470-0010}}</ref>

When a supernova occurs inside a small dense cloud of circumstellar material, it will produce a shock wave that can efficiently convert a high fraction of the kinetic energy into electromagnetic radiation. Even though the initial energy was entirely normal the resulting supernova will have high luminosity and extended duration since it does not rely on exponential radioactive decay. This type of event may cause type IIn hypernovae.<ref>{{Cite journal |last1=Woosley |first1=S. E. |last2=Blinnikov |first2=S. |last3=Heger |first3=Alexander |date=15 November 2007 |title=Pulsational pair instability as an explanation for the most luminous supernovae |url=https://www.nature.com/articles/nature06333 |journal=Nature |language=en |volume=450 |issue=7168 |pages=390–392 |bibcode=2007Natur.450..390W |arxiv=0710.3314 |doi=10.1038/nature06333 |pmid=18004378 |s2cid=2925738 |issn=0028-0836}}</ref><ref>{{Cite journal |last1=Barkov |first1=Maxim V. |last2=Komissarov |first2=Serguei S. |date=21 July 2011 |title=Recycling of neutron stars in common envelopes and hypernova explosions: Recycling of neutron stars and hypernovae |doi-access=free |journal=Monthly Notices of the Royal Astronomical Society |language=en |volume=415 |issue=1 |pages=944–958 |doi=10.1111/j.1365-2966.2011.18762.x |bibcode=2011MNRAS.415..944B |arxiv=1012.4565 }}</ref>

Although pair-instability supernovae are core collapse supernovae with spectra and light curves similar to type II-P, the nature after core collapse is more like that of a giant type Ia with runaway fusion of carbon, oxygen and silicon. The total energy released by the highest-mass events is comparable to other core collapse supernovae but neutrino production is thought to be very low, hence the kinetic and electromagnetic energy released is very high. The cores of these stars are much larger than any white dwarf and the amount of radioactive nickel and other heavy elements ejected from their cores can be orders of magnitude higher, with consequently high visual luminosity.<ref>{{Cite journal |last1=Wright |first1=Warren P. |last2=Gilmer |first2=Matthew S. |last3=Fröhlich |first3=Carla |last4=Kneller |first4=James P. |date=13 November 2017 |title=Neutrino signal from pair-instability supernovae |url=https://link.aps.org/doi/10.1103/PhysRevD.96.103008 |journal=Physical Review D |language=en |volume=96 |issue=10 |pages=103008 |bibcode=2017PhRvD..96j3008W |arxiv=1706.08410 |doi=10.1103/PhysRevD.96.103008 |s2cid=119487775 |issn=2470-0010}}</ref>