Editing Synchrotron radiation (section)

{{Short description|Electromagnetic radiation}}
{{About|the physical phenomenon|details on its production and applications in laboratories|Synchrotron light source}}

'''Synchrotron radiation''' (also known as '''magnetobremsstrahlung''') is the [[electromagnetic radiation]] emitted when [[Theory of relativity|relativistic]] charged particles are subject to an acceleration perpendicular to their velocity ({{math|'''a''' &perp; '''v'''}}). It is produced artificially in some types of [[particle accelerator]]s or naturally by fast electrons moving through magnetic fields. The radiation produced in this way has a characteristic [[polarization (waves)|polarization]], and the frequencies generated can range over a large portion of the [[electromagnetic spectrum]].<ref>{{Cite journal |date=2010-03-02 |title=What is synchrotron radiation? |url=https://www.nist.gov/pml/sensor-science/what-synchrotron-radiation |journal=NIST |language=en}}</ref>
[[File:Radiacao escalar SdS.pdf|thumb|Pictorial representation of the radiation emission process by a source moving around a [[Schwarzschild metric|Schwarzschild black hole]] in a [[de Sitter universe]]. ]]
[[File:Em perp field.png|thumb|Electromagnetic field observed far from the source (in arbitrary unit) of a positive accelerated point charge. When the velocity increase, the radiation concentrates along the trajectory. This field can be calculated using [[Liénard–Wiechert potential]].]]

Synchrotron radiation is similar to [[bremsstrahlung|bremsstrahlung radiation]], which is emitted by a charged particle when the acceleration is parallel to the direction of motion.  The general term for radiation emitted by particles in a magnetic field is ''gyromagnetic radiation'', for which synchrotron radiation is the ultra-relativistic special case. Radiation emitted by charged particles moving non-relativistically in a magnetic field is called [[cyclotron radiation|cyclotron emission]].<ref>{{cite journal|last1=Monreal|first1=Benjamin|title=Single-electron cyclotron radiation|journal=Physics Today|date=Jan 2016|volume=69|issue=1|page=70|doi=10.1063/pt.3.3060|bibcode=2016PhT....69a..70M|doi-access=free}}</ref> For particles in the mildly relativistic range (≈85% of the speed of light), the emission is termed ''gyro-synchrotron radiation''.<ref>{{cite web |last1=Chen |first1=Bin |title=Radiative processes from energetic particles II: Gyromagnetic radiation |url=https://web.njit.edu/~binchen/phys780/LectureNotes/lec21.pdf |website=New Jersey Institute of Technology |access-date=10 December 2021}}</ref>

In [[astrophysics]], synchrotron emission occurs, for instance, due to ultra-relativistic motion of a charged particle around a [[black hole]].<ref>{{Cite journal|last1=Brito|first1=João P. B.|last2=Bernar|first2=Rafael P.|last3=Crispino|first3=Luís C. B.|date=11 June 2020|title=Synchrotron geodesic radiation in Schwarzschild–de Sitter spacetime|journal=Physical Review D|language=en|volume=101|issue=12|pages=124019|doi=10.1103/PhysRevD.101.124019|issn=2470-0010|arxiv=2006.08887|bibcode=2020PhRvD.101l4019B|s2cid=219708236}}</ref> When the source follows a circular [[Geodesics in general relativity|geodesic]] around the black hole, the synchrotron radiation occurs for orbits close to the [[Photon sphere|photosphere]] where the motion is in the [[Ultrarelativistic limit|ultra-relativistic]] regime. 
[[File:Syncrotron.svg|thumb|Synchrotron radiation from a bending magnet]] [[File:Undulator (numbers).svg|thumb|Synchrotron radiation from an undulator]]
[[File:Emmaalexander synchrotron.png|thumb|Synchrotron radiation from an astronomical source]]