Synchrotron radiation

This article is about the physical phenomenon. For details on its production and applications in laboratories, see Synchrotron light source.

Synchrotron radiation (also known as magnetobremsstrahlung) is the electromagnetic radiation emitted when relativistic charged particles are subject to an acceleration perpendicular to their velocity (a ⊥ v). It is produced artificially in some types of particle accelerators or naturally by fast electrons moving through magnetic fields. The radiation produced in this way has a characteristic polarization, and the frequencies generated can range over a large portion of the electromagnetic spectrum.[1]

Pictorial representation of the radiation emission process by a source moving around a Schwarzschild black hole in a de Sitter universe.
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 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 emission.[2] For particles in the mildly relativistic range (≈85% of the speed of light), the emission is termed gyro-synchrotron radiation.[3]

In astrophysics, synchrotron emission occurs, for instance, due to ultra-relativistic motion of a charged particle around a black hole.[4] When the source follows a circular geodesic around the black hole, the synchrotron radiation occurs for orbits close to the photosphere where the motion is in the ultra-relativistic regime.

Synchrotron radiation from a bending magnet
Synchrotron radiation from an undulator
Synchrotron radiation from an astronomical source
  1. ^ "What is synchrotron radiation?". NIST. 2010-03-02.
  2. ^ Monreal, Benjamin (Jan 2016). "Single-electron cyclotron radiation". Physics Today. 69 (1): 70. Bibcode:2016PhT....69a..70M. doi:10.1063/pt.3.3060.
  3. ^ Chen, Bin. "Radiative processes from energetic particles II: Gyromagnetic radiation" (PDF). New Jersey Institute of Technology. Retrieved 10 December 2021.
  4. ^ Brito, João P. B.; Bernar, Rafael P.; Crispino, Luís C. B. (11 June 2020). "Synchrotron geodesic radiation in Schwarzschild–de Sitter spacetime". Physical Review D. 101 (12): 124019. arXiv:2006.08887. Bibcode:2020PhRvD.101l4019B. doi:10.1103/PhysRevD.101.124019. ISSN 2470-0010. S2CID 219708236.