Editing Magnetar (section)

==Description==
Like other [[Neutron star|neutron stars]], magnetars are around {{convert|20|km}} in diameter, and have a mass of about 1.4 solar masses. They are formed by the collapse of a star with a mass 10–25 times that of the [[Sun]]. The density of the interior of a magnetar is such that a tablespoon of its substance would have a mass of over 100 million tons.<ref name="Ward"/> Magnetars are differentiated from other neutron stars by having even stronger magnetic fields, and by rotating more slowly in comparison. Most observed magnetars rotate once every two to ten seconds,<ref name="sciam_article">
{{cite journal |date=April 2010 |title=Grand unification of neutron stars |journal=Proceedings of the National Academy of Sciences |publisher=Proceedings of the National Academy of Sciences of the United States of America |doi=10.1073/pnas.1000812107 |doi-access=free |last1=Kaspi |first1=V. M. |volume=107 |issue=16 |pages=7147–7152 |pmid=20404205 |pmc=2867699 |arxiv=1005.0876 |bibcode=2010PNAS..107.7147K}}
</ref> whereas typical neutron stars, observed as radio [[pulsar]]s, rotate one to ten times per second.<ref name="nrao">{{cite web |url=https://www.cv.nrao.edu/~sransom/web/Ch6.html |title=Pulsar Properties (Essential radio Astronomy) |publisher=National Radio Astronomy Observatory |access-date=26 Feb 2021 |first1=J. J. |last1=Condon |first2=S. M. |last2=Ransom |name-list-style=amp }}</ref> A magnetar's magnetic field gives rise to very strong and characteristic bursts of X-rays and gamma rays. The active life of a magnetar is short compared to other celestial bodies. Their strong magnetic fields decay after about 10,000 years, after which activity and strong X-ray emission cease. Given the number of magnetars observable today, one estimate puts the number of inactive magnetars in the [[Milky Way]] at 30 million or more.<ref name="sciam_article"/>

[[Quake (natural phenomenon)#Starquake|Starquake]]s triggered on the surface of the magnetar disturb the magnetic field which encompasses it, often leading to extremely powerful [[Gamma-ray burst|gamma-ray flare]] emissions which have been recorded on Earth in 1979, 1998 and 2004.<ref name="journal2"/>
[[File:PIA23863-NeutronStars-Types-20200624.jpg|thumb|center|800px|<div align="center">Neutron Star Types (24 June 2020)</div>]]

=== Magnetic field ===
Magnetars are characterized by their extremely powerful magnetic fields of ~10<sup>9</sup> to 10<sup>11</sup> [[Tesla (unit)|T]].<ref name="mcgill"/> These magnetic fields are a hundred million times stronger than any man-made magnet,<ref>{{cite web |url=http://www.fzd.de/db/Cms?pNid=1482 |title=HLD user program, at Dresden High Magnetic Field Laboratory |access-date = 2009-02-04}}</ref> and about a trillion times more powerful than the [[Earth's magnetic field|field surrounding Earth]].<ref>{{cite news |url=https://skyandtelescope.org/astronomy-news/the-brightest-blast |title=The Brightest Blast |first=Robert |last=Naeye |date=February 18, 2005 |work=[[Sky & Telescope]] |access-date=10 November 2020}}</ref> Earth has a [[geomagnetic]] field of 30–60 microteslas, and a [[neodymium magnet|neodymium-based, rare-earth magnet]] has a field of about 1.25 tesla, with a magnetic energy density of 4.0 × 10<sup>5</sup> J/m<sup>3</sup>. A magnetar's 10<sup>10</sup> tesla field, by contrast, has an energy density of {{val|4.0|e=25|u=J/m3}}, with an [[Mass–energy equivalence#Massless particles|''E''/''c''<sup>2</sup>]] mass density more than 10,000 times that of [[lead]]. The magnetic field of a magnetar would be lethal even at a distance of 1,000&nbsp;km due to the strong magnetic field distorting the electron clouds of the subject's constituent atoms, rendering the chemistry of sustaining life impossible.<ref>{{cite web |last=Duncan |first=Robert |title='MAGNETARS', SOFT GAMMA REPEATERS & VERY STRONG MAGNETIC FIELDS |url=http://solomon.as.utexas.edu/magnetar.html |archive-url= |archive-date= |access-date= |publisher=University of Texas}}</ref> At a distance of halfway from Earth to the Moon, an average distance between the Earth and the Moon being {{Convert|384400|km|abbr=in}}, a magnetar could wipe information from the magnetic stripes of all [[credit card]]s on Earth.<ref>{{cite web |url=http://www.nasa.gov/vision/universe/watchtheskies/swift_nsu_0205.html |title=Cosmic Explosion Among the Brightest in Recorded History |date=February 18, 2005 |first=Christopher |last=Wanjek |publisher=[[NASA]] |access-date=17 December 2007}}</ref> {{as of|2020}}, they are the most powerful magnetic objects detected throughout the universe.<ref name="journal2">Kouveliotou, C.; Duncan, R. C.; Thompson, C. (February 2003). "[http://solomon.as.utexas.edu/~duncan/sciam.pdf Magnetars] {{webarchive |url=https://web.archive.org/web/20070611144829/http://solomon.as.utexas.edu/~duncan/sciam.pdf |date=2007-06-11 }}". ''[[Scientific American]]''; Page 36.</ref><ref>{{cite web |url=https://science.nasa.gov/newhome/headlines/ast20may98_1.htm |title="Magnetar" discovery solves 19-year-old mystery |date=May 20, 1998 |first=Dave |last=Dooling |work=Science@NASA Headline News |access-date=17 December 2007 |archive-url=https://web.archive.org/web/20071214033454/http://science.nasa.gov/newhome/headlines/ast20may98_1.htm |archive-date=14 December 2007 |url-status=dead }}</ref>

As described in the February 2003 ''[[Scientific American]]'' cover story, remarkable things happen within a magnetic field of magnetar strength. "[[X-ray]] [[photon]]s readily split in two or merge. The vacuum itself is [[Vacuum_polarization|polarized]], becoming strongly [[birefringent]], like a [[calcite]] crystal. [[Atom]]s are deformed into long cylinders thinner than the quantum-relativistic [[de Broglie wavelength]] of an electron."<ref name="journal"/> In a field of about 10<sup>5</sup> teslas [[atomic orbital]]s deform into rod shapes. At 10<sup>10</sup> teslas, a [[hydrogen atom]] becomes 200 times as narrow as its normal diameter.<ref name="journal">Kouveliotou, C.; Duncan, R. C.; Thompson, C. (February 2003). "[http://solomon.as.utexas.edu/magnetar.html#SciAm Magnetars]". ''[https://solomon.as.utexas.edu/sciam.pdf Scientific American]''; Page 41.</ref>

====Origins of magnetic fields====
The dominant model of the strong fields of magnetars is that it results from a [[magnetohydrodynamic dynamo]] process in the turbulent, extremely dense conducting fluid that exists before the neutron star settles into its equilibrium configuration.<ref>{{Cite journal |last1=Thompson |first1=Christopher |last2=Duncan |first2=Robert C. |date=1993 |title=Neutron Star Dynamos and the Origins of Pulsar Magnetism |url=https://articles.adsabs.harvard.edu/pdf/1993ApJ...408..194T |journal=Astrophysical Journal |volume=408 |pages=194–217 |doi=10.1086/172580 |bibcode=1993ApJ...408..194T |via=NASA Astrophysics Data System |doi-access= }}</ref> These fields then persist due to persistent currents in a proton-superconductor phase of matter that exists at an intermediate depth within the neutron star (where neutrons predominate by mass). A similar magnetohydrodynamic dynamo process produces even more intense transient fields during [[Neutron star merger|coalescence of a pair of neutron stars]].<ref>{{Cite journal
|last1        = Price
|first1       = Daniel J.
|last2        = Rosswog
|first2       = Stephan
|title        = Producing Ultrastrong Magnetic Fields in Neutron Star Mergers
|doi          = 10.1126/science.1125201
|journal      = Science
|volume       = 312
|issue        = 5774
|pages        = 719–722
|date         = May 2006
|pmid         = 16574823
|arxiv        = astro-ph/0603845
|url          = http://users.monash.edu.au/~dprice/research/nsmag/
|bibcode      = 2006Sci...312..719P
|s2cid        = 30023248
|access-date  = 2012-07-13
|archive-date = 2018-07-17
|archive-url  = https://web.archive.org/web/20180717141702/http://users.monash.edu.au/~dprice/research/nsmag/
|url-status   = dead
}} {{open access}}</ref> An alternative model is that they simply result from the collapse of stars with unusually strong magnetic fields.<ref>{{Cite journal
| last1 = Zhou | first1 = Ping
| last2 = Vink | first2 = Jacco
| last3 = Safi-Harb | first3 = Samar
| last4 = Miceli | first4 = Marco
| title = Spatially resolved X-ray study of supernova remnants that host magnetars: Implication of their fossil field origin
| doi = 10.1051/0004-6361/201936002
| journal = Astronomy & Astrophysics
| volume = 629
| issue = A51
| pages = 12
| date = September 2019
| arxiv = 1909.01922
| bibcode = 2019A&A...629A..51Z
| s2cid = 201252025
}} {{open access}}</ref>

=== Formation ===
[[Image:Dust Ring around Magnetar1.jpg|thumb|right|Magnetar SGR 1900+14 (center of image) showing a surrounding ring of gas 7 light-years across in infrared light, as seen by the [[Spitzer Space Telescope]]. The magnetar itself is not visible at this wavelength but has been seen in X-ray light.]]
In a [[supernova]], a star collapses to a neutron star, and its magnetic field increases dramatically in strength through conservation of [[magnetic flux]]. Halving a linear dimension increases the magnetic field strength fourfold. Duncan and Thompson calculated that when the spin, temperature and magnetic field of a newly formed neutron star falls into the right ranges, a [[Dynamo theory|dynamo mechanism]] could act, converting heat and rotational energy into magnetic energy and increasing the magnetic field, normally an already enormous 10<sup>8</sup> [[Tesla (unit)|tesla]]s, to more than 10<sup>11</sup> teslas (or 10<sup>15</sup> [[gauss (unit)|gauss]]). The result is a ''magnetar''.<ref>Kouveliotou, p.237</ref> It is estimated that about one in ten supernova explosions results in a magnetar rather than a more standard neutron star or pulsar.<ref>{{Cite journal |last1 = Popov |first1 = S. B. |last2 = Prokhorov |first2 = M. E. |doi = 10.1111/j.1365-2966.2005.09983.x |title = Progenitors with enhanced rotation and the origin of magnetars |journal = Monthly Notices of the Royal Astronomical Society |volume = 367 |issue = 2 |pages = 732–736 |date=April 2006 |doi-access = free
|arxiv = astro-ph/0505406 |bibcode = 2006MNRAS.367..732P |s2cid = 14930432
}} {{open access}}</ref>

=== 1979 discovery ===
On March 5, 1979, a few months after the successful dropping of [[Lander (spacecraft)|landers]] into the atmosphere of [[Venus]], the two uncrewed Soviet spaceprobes [[Venera 11]] and [[Venera 12|12]], then in [[heliocentric orbit]], were hit by a blast of gamma radiation at approximately 10:51 EST. This contact raised the radiation readings on both the probes from a normal 100 counts per second to over 200,000 counts a second in only a fraction of a millisecond.<ref name="journal"/>

Eleven seconds later, [[Helios (spacecraft)|Helios 2]], a [[NASA]] probe, itself in orbit around the [[Sun]], was saturated by the blast of radiation. It soon hit Venus, where the [[Pioneer Venus Orbiter]]'s detectors were overcome by the wave. Shortly thereafter the gamma rays inundated the detectors of three [[U.S. Department of Defense]] [[Vela (satellite)|Vela satellites]], the [[Prognoz (satellite)|Soviet Prognoz 7 satellite]], and the [[Einstein Observatory]], all orbiting Earth. Before exiting the [[Solar System]] the radiation was detected by the [[International Cometary Explorer|International Sun–Earth Explorer]] in [[halo orbit]].<ref name="journal"/>

This was the strongest wave of extra-solar gamma rays ever detected at over 100 times as intense as any previously known burst. Given the [[speed of light]] and its detection by several widely dispersed spacecraft, the source of the [[gamma radiation]] could be triangulated to within an accuracy of approximately 2 [[arcseconds]].<ref>{{cite journal
| title = Precise source location of the anomalous 1979 March 5 gamma-ray transient
| journal = The Astrophysical Journal
| volume = 255
|date=Apr 1982
| page = L45–L48
| doi = 10.1086/183766
| author = Cline, T. L., Desai, U. D., Teegarden, B. J., Evans, W. D., Klebesadel, R. W., Laros, J. G.
|bibcode = 1982ApJ...255L..45C
| hdl = 2060/19820012236
| hdl-access = free
}} {{open access}}</ref> The direction of the source corresponded with [[SGR 0525−66]], the remnant of a star that had exploded as a supernova around 3000 BCE.<ref name="journal2"/> It was in the [[Large Magellanic Cloud]] and the event was named [[GRB 790305b]], the first-observed SGR megaflare.

===Recent discoveries===
[[File:Artist’s impression of a gamma-ray burst and supernova powered by a magnetar.jpg|thumb|Artist's impression of a gamma-ray burst and supernova powered by a magnetar<ref>{{cite web |title=Biggest Explosions in the Universe Powered by Strongest Magnets |url=http://www.eso.org/public/news/eso1527/ |access-date=9 July 2015}}</ref>]]
On February 21, 2008, it was announced that NASA and researchers at [[McGill University]] had discovered a neutron star with the properties of a radio pulsar which emitted some magnetically powered bursts, like a magnetar. This suggests that magnetars are not merely a rare type of pulsar but may be a (possibly reversible) phase in the lives of some pulsars.<ref>{{Cite web |url=https://www.mcgill.ca/channels/news/jekyll-hyde-neutron-star-discovered-researchers-29230 |title=Jekyll-Hyde neutron star discovered by researchers] |date=21 February 2008 |publisher=[[McGill University]] |first=Mark |last=Shainblum}}</ref> On September 24, 2008, [[ESO]] announced what it ascertained was the first optically active magnetar-candidate yet discovered, using ESO's [[Very Large Telescope]]. The newly discovered object was designated SWIFT J195509+261406.<ref name="eso.org">{{cite web |url=http://www.eso.org/public/news/eso0831/ <!-- old URL, retained for archival purposes: http://www.eso.org/public/outreach/press-rel/pr-2008/pr-31-08.html --> |title=The Hibernating Stellar Magnet: First Optically Active Magnetar-Candidate Discovered |date=23 September 2008 |publisher=[[European Southern Observatory|ESO]]}}</ref> On September 1, 2014, [[ESA]] released news of a magnetar close to supernova remnant [[Kesteven 79]]. Astronomers from Europe and China discovered this magnetar, named 3XMM J185246.6+003317, in 2013 by looking at images that had been taken in 2008 and 2009.<ref>{{Cite web |url=http://www.esa.int/spaceinimages/Images/2014/08/Magnetar_discovered_close_to_supernova_remnant_Kesteven_79 |title=Magnetar discovered close to supernova remnant Kesteven 79 |date=1 September 2014 |publisher=ESA/XMM-Newton/ Ping Zhou, Nanjing University, China}}</ref> In 2013, a magnetar [[SGR J1745−2900|PSR J1745−2900]] was discovered, which orbits the [[black hole]] in the [[Sagittarius A*]] system. This object provides a valuable tool for studying the ionized [[interstellar medium]] toward the [[Galactic Center]]. In 2018, the temporary result of the [[GW170817#Astrophysical origin and products|merger of two neutron stars]] was determined to be a hypermassive magnetar, which shortly collapsed into a black hole.<ref name="MNRAS-20180904">{{Cite journal |last1=van&nbsp;Putten |first1=Maurice H P M |last2=Della&nbsp;Valle |first2=Massimo |date=2018-09-04 |title=Observational evidence for extended emission to GW170817 |journal=Monthly Notices of the Royal Astronomical Society: Letters |language=en |volume=482 |issue=1 |pages=L46–L49 |doi=10.1093/mnrasl/sly166 |doi-access=free |issn=1745-3925 |arxiv=1806.02165 |bibcode=2019MNRAS.482L..46V |s2cid=119216166}}</ref>

In April 2020, a possible link between [[fast radio burst]]s (FRBs) and magnetars was suggested, based on observations of [[SGR 1935+2154]], a likely magnetar located in the [[Milky Way]] galaxy.<ref name="AT-20201104">{{cite news |last=Timmer |first=John |title=We finally know what has been making fast radio bursts - Magnetars, a type of neutron star, can produce the previously enigmatic bursts. |url=https://arstechnica.com/science/2020/11/its-coming-from-inside-the-galaxy-first-fast-radio-burst-source-idd/ |date=4 November 2020 |work=[[Ars Technica]] |access-date=4 November 2020 }}</ref><ref name="NASA-20201104">{{cite news |last1=Cofield |first1=Calla |last2=Andreoli |first2=Calire |last3=Reddy |first3=Francis |title=NASA Missions Help Pinpoint the Source of a Unique X-ray, Radio Burst |url=https://www.jpl.nasa.gov/news/news.php?feature=7776 |date=4 November 2020 |work=[[NASA]] |access-date=4 November 2020 }}</ref><ref name="NAT-20201104">{{cite journal |author=Andersen, B. |display-authors=et al.|title=A bright millisecond-duration radio burst from a Galactic magnetar |url=https://www.nature.com/articles/s41586-020-2863-y |date=4 November 2020 |journal=[[Nature (journal)|Nature]] |volume=587 |issue=7832|pages=54–58 |doi=10.1038/s41586-020-2863-y |pmid=33149292|arxiv=2005.10324|bibcode=2020Natur.587...54C|s2cid=218763435|access-date=5 November 2020 }}</ref><ref name="SA-20200505">{{cite news |last=Drake |first=Nadia |author-link=Nadia Drake |title='Magnetic Star' Radio Waves Could Solve the Mystery of Fast Radio Bursts - The surprise detection of a radio burst from a neutron star in our galaxy might reveal the origin of a bigger cosmological phenomenon |url=https://www.scientificamerican.com/article/magnetic-star-radio-waves-could-solve-the-mystery-of-fast-radio-bursts/ |date=5 May 2020 |work=[[Scientific American]] |access-date=9 May 2020 }}</ref><ref name="SA-20200501">{{cite news |last=Starr |first=Michelle |title=Exclusive: We Might Have First-Ever Detection of a Fast Radio Burst in Our Own Galaxy |url=https://www.sciencealert.com/a-galactic-magnetar-just-spat-out-something-shockingly-like-a-fast-radio-burst |date=1 May 2020 |work=ScienceAlert.com |access-date=9 May 2020 }}</ref>