Spectral energy distribution
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A spectral energy distribution (SED) is a plot of energy versus frequency or wavelength of electromagnetic or mechanical radiation, most commonly light (not to be confused with a 'spectrum' of flux density vs frequency or wavelength).[1] It is used in many branches of astronomy to characterize astronomical sources. Features of the SED found in specific regions of the electromagnetic spectrum, such as absorption or emission lines, provide information about the object being studied.[2] For example, in radio astronomy they are used to show the emission from synchrotron radiation, free-free emission and other emission mechanisms.[3] In infrared astronomy, SEDs can be used to investigate young stellar objects, galaxies at high redshift, and objects heavily obscured by dust.[4][2]
Detector for spectral energy distribution
[edit]The count rates observed from a given astronomical radiation source have no simple relationship to the flux from that source, such as might be incident at the top of the Earth's atmosphere.[5] This lack of a simple relationship is due in no small part to the complex properties of radiation detectors.[5]
These detector properties can be divided into
- those that merely attenuate the beam, including
- residual atmosphere between source and detector,
- absorption in the detector window when present,
- quantum efficiency of the detecting medium,[5]
- those that redistribute the beam in detected energy, such as
- fluorescent photon escape phenomena,
- inherent energy resolution of the detector.[5]
The type of detector required to measure a spectral energy distribution changes based on the portion of the electromagnetic spectrum being observed.[2]
See also
[edit]References
[edit]- ↑ "SED plots - CoolWiki". coolwiki.ipac.caltech.edu. Retrieved 27 February 2018.
- 1 2 3 Iyer, Kartheik G.; Pacifici, Camilla; Calistro-Rivera, Gabriela; Lovell, Christopher C. (2025-02-24), The Spectral Energy Distributions of Galaxies, arXiv, doi:10.48550/arXiv.2502.17680, arXiv:2502.17680, retrieved 2026-08-02
- ↑ Harvey, V M; Franzen, T; Morgan, J; Seymour, N (2018-05-01). "A novel approach for characterizing broad-band radio spectral energy distributions". Monthly Notices of the Royal Astronomical Society. 476 (2): 2717–2730. doi:10.1093/mnras/sty386. ISSN 0035-8711.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ↑ Martínez-Galarza, J. Rafael; Protopapas, Pavlos; Smith, Howard A.; Morales, Esteban F. E. (2018-08-30). "Unraveling the Spectral Energy Distributions of Clustered YSOs". The Astrophysical Journal. 864 (1): 71. doi:10.3847/1538-4357/aad503. ISSN 0004-637X.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - 1 2 3 4 Dolan JF (Aug 1972). "The Direct Reduction of Astronomical X-Ray Spectra". Astrophys. Space Sci. 17 (2): 472–81. Bibcode:1972Ap&SS..17..472D. doi:10.1007/BF00642917. S2CID 123125127.
Further reading
[edit]- Eberhard Haug & Werner Nakel (2004). The elementary process of Bremsstrahlung. River Edge NJ: World Scientific. p. Scientific lecture notes in physics, vol. 73. ISBN 978-981-238-578-9.
- Jakob Walcher; Brent Groves; Tamás Budavári; Daniel Dale. "Fitting the spectral energy distributions of galaxies". Archived from the original on 2014-08-14.
External links
[edit]- The High Energy Astrophysics Science Archive Research Center (HEASARC) at NASA
- The Science of Spectroscopy Archived 2019-03-23 at the Wayback Machine