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| The '''Wolf effect''' (sometimes '''Wolf shift''') is a ] shift in the ].<ref>Emil Wolf, "" (2001) , {{ISBN|981-02-4204-2}}.</ref> | |||
| ), Doppler-shifted (dotted line ), and shifted by the process described in this paper (dashed line ), both by a relative amount z = 0.0714. The FWHM of both lines was taken as 84 km s<sup>-1</sup>. The constant ''C'' in eq. (23) was chosen so that the height of the | |||
| The phenomenon occurs in several closely related phenomena in ], with analogous effects occurring in the ] of light.<ref name="james">{{cite journal | last=James | first=Daniel F V | title=The Wolf effect and the redshift of quasars | journal=Pure and Applied Optics: Journal of the European Optical Society Part A | publisher=IOP Publishing | volume=7 | issue=5 | year=1998 | issn=0963-9659 | doi=10.1088/0963-9659/7/5/006 | pages=959–970|arxiv=astro-ph/9807205| bibcode=1998PApOp...7..959J | s2cid=17670250 }}</ref> It was first predicted by ] in 1987<ref name="wolf87nature">{{cite journal | last=Wolf | first=Emil | title=Non-cosmological redshifts of spectral lines | journal=Nature | publisher=Springer Science and Business Media LLC | volume=326 | issue=6111 | year=1987 | issn=0028-0836 | doi=10.1038/326363a0 | pages=363–365| bibcode=1987Natur.326..363W | s2cid=4337925 }}</ref><ref>{{cite journal | last=Wolf | first=Emil | title=Redshifts and blueshifts of spectral lines caused by source correlations | journal=Optics Communications | publisher=Elsevier BV | volume=62 | issue=1 | year=1987 | issn=0030-4018 | doi=10.1016/0030-4018(87)90057-5 | pages=12–16| bibcode=1987OptCo..62...12W | doi-access=free }}</ref> and subsequently confirmed in the laboratory in acoustic sources by Mark F. Bocko, ], and Robert S. Knox,<ref>{{cite journal | last1=Bocko | first1=Mark F. | last2=Douglass | first2=David H. | last3=Knox | first3=Robert S. | title=Observation of frequency shifts of spectral lines due to source correlations | journal=Physical Review Letters | publisher=American Physical Society (APS) | volume=58 | issue=25 | date=1987-06-22 | issn=0031-9007 | doi=10.1103/physrevlett.58.2649 | pages=2649–2651| pmid=10034809 | bibcode=1987PhRvL..58.2649B }}</ref> and a year later in optic sources by Dean Faklis and George Morris in 1988.<ref>{{cite journal | last1=Faklis | first1=Dean | last2=Morris | first2=G. Michael | title=Spectral shifts produced by source correlations | journal=Optics Letters | publisher=The Optical Society | volume=13 | issue=1 | date=1988-01-01 | issn=0146-9592 | doi=10.1364/ol.13.000004 | page=4—6| pmid=19741961 | bibcode=1988OptL...13....4F }}</ref> | |||
| stronger shifted line is the same as for the Doppler-shifted line. For shifts induced by the correlation mechanism and shown in the figure, σ = 50 μm, θ = 30°, and θ'= 21°89.</ref> ]] | |||
| The '''Wolf Effect''' (sometimes ''Wolf shift''), named after ], is a ] shift in the ] that has been considered to be a new ] mechanism.<ref>], "" (2001) , ISBN 981-02-4204-2.</ref> <ref>'' (2005) edited by M. Mamone Capria, ISBN: 1-58603-462-6.</ref> <ref>S. Roy, S. Data, in '''' (2002) by Colin Ray Wilks, Richard L. Amoroso, Geoffrey Hunter, Menas Kafatos; , ISBN: 1-4020-0885-6</ref> The phenomenon occurs in several closely related phenomena in radiation physics, with analogous effects occurring in the ] of light.<ref>James, Daniel, "" (1998) ''Pure Appl. Opt''. 7: 959-970. (, PDF)</ref> It was first predicted by ] in 1987 <ref name="wolf87nature">Wolf, Emil "" (1987) ''Nature'' 326: 363—365.</ref> <ref>Wolf, Emil, "" (1987) ''Optics Communications'' 62: 12—16.</ref> and subsequently confirmed in the laboratory by Dean Faklis and George Morris in 1988 <ref>Bocko, Mark F., Douglass, David H., and Knox, Robert S., "" (1987) ''Physical Review Letters'' 58: 2649—2651.</ref> <ref>Faklis, Dean, and Morris, George Michael, "" (1988) ''Optics Letters'' 13 (1): 4—6.</ref>. Under certain conditions, the shift may be distortion free, Wolf and James write: | |||
| :"A review is also presented of recent research, which has revealed that under certain circumstances the changes in the spectrum of light scattered on random media may imitate the ], even though the source, the medium and the observer are all at rest with respect to one another. This expression shows that the ''relative frequency shift is independent of the central frequency ω<sub>0</sub> of the incident light'' and thus imitates the Doppler effect."<ref name="wolf96james">Wolf, Emil, and James, Daniel F. V., "" (1996) ''Reports on Progress in Physics'' 59: 771—818. (, PDF)</ref> | |||
| The effect has been regarded by a small number of researchers as being possibly significant in the spectra of ]s. Wolf has gone as far as to advocate the effect as a '']'',<ref name="wolf87nature" />, apparently a reference to the controversies surrounding the nature of quasars that occurred in the ] where certain astronomers believed that quasars were local and others believed that quasars were at cosmological distances. Quasars have subsequently been found to be the distant cores of ] (AGN) and thus the Wolf Effect is not seen as a major component in the redshift of quasars by the vast majority of astrophysicists. | |||
| ==Theoretical description== | ==Theoretical description== | ||
| ⚫ | In ], two non-] sources that emit beamed energy can interact in a way that causes a shift in the spectral lines. It is analogous to a pair of tuning forks with similar frequencies (pitches), connected together mechanically with a sounding board; there is a strong coupling that results in the resonant frequencies getting "dragged down" in pitch. The Wolf Effect requires that the waves from the sources are partially ] - the wavefronts being partially in phase. ] light is coherent while candlelight is incoherent, each photon having random phase. It can produce either redshifts or blueshifts, depending on the observer's point of view, but is redshifted when the observer is head-on.<ref name="wolf87nature" /> | ||
| ⚫ | For two sources interacting while separated by a vacuum, the Wolf effect cannot produce shifts greater than the ] of the source ], since it is a position-dependent change in the distribution of the source spectrum, not a method by which new frequencies may be generated. However, when interacting with a medium, in combination with effects such as ] it may produce distorted shifts greater than the linewidth of the source. | ||
| ⚫ | In ], |
||
| The Wolf Effect requires that the waves from the sources are partially ] - the wavefronts being partially in phase. ] light is coherent while candle light is incoherent, each photon having random phase. | |||
| The Wolf Effect can produce either redshifts or blueshifts, depending on the observer's point of view, but is redshifted when the observer is head-on.<ref name="wolf87nature" /> A subsequent 1999 article by Sisir Roy ''et al.'' have suggested that the Wolf Effect may explain discordant redshift in certain quasars <ref>Roy, Sisir, Kafatos, Menas, and Datta, Suman, "" (2000) ''Astronomy and Astrophysics'', v.353, p.1134-1138 353: 1134—1138.</ref>. | |||
| ⚫ | For two sources interacting while separated by a vacuum, the Wolf effect cannot produce shifts greater than the ] of the source ], since it is a position-dependent change in the distribution of the source spectrum, not a method by which new frequencies may be generated. However, when interacting with a medium, in combination with effects such as ] it may produce shifts greater than the linewidth of the source. | ||
| ==Wolf effect and Quasars== | |||
| An example of such a medium which could produce Doppler-like shifts was found in 1990 by Daniel James, Malcolm Savedoff, Malcolm and Emil Wolf,<ref>James, Daniel F. V., Savedoff, Malcolm P., and Wolf, Emil, "" (1990) ''Astrophysical Journal'' 359: 67—71. (, PDF)</ref> and involved a highly ''statistically ]'' scattering medium, that is compatible with current models of quasars. A "no blueshift" condition has also been found by Datta, S. ''et al.'', <ref>Datta, S., Roy, S., Roy, M., and Moles, M., "" (1998) ''Physical Review A'' 58 (1): 720—723.</ref> <ref>Roy, S., Kafatos, M., and Datta, S., " (1999) astro-ph/9904061</ref>. | |||
| Wolf and James note <ref name="wolf96james" /> that: | |||
| :"Although we make no claim that correlation-induced spectral shifts account for all, or even for a majority, of the observed shifts of lines in the spectra of extra-galactic objects, we note the possibility that correlation-induced spectral shifts may contribute to the shifts observed in the spectra of some astronomical objects such as quasars. They might help to resolve a long-standing controversy relating to pairs of astronomical objects whose spectra have different redshifts, but which appear to be physically connected, such as the pair consisting of the galaxy NGC 4319 (''z'' = 0.006) and the quasar Markarian 205 (''z ''= 0.007/ (Arp 1971, Sulentic 1983). The possible 'excess' redshift observed in the spectrum of the quasar in such a galaxy-quasar pair may perhaps be induced by the mechanism that we have just discussed". | |||
| ==Notes== | ==Notes== | ||
| <div style="font-size: 95%"> | <div style="font-size: 95%"> | ||
| {{Reflist}} | |||
| <!--See ] for an explanation of how to generate footnotes using the <ref(erences/)> tags--> | |||
| <references/> | |||
| </div> | </div> | ||
| ==See also== | |||
| * ] | |||
| ] | ] | ||
| ] | ] | ||
| {{scattering-stub}} | |||
| {{spectroscopy-stub}} | |||
Latest revision as of 05:52, 11 December 2023
The Wolf effect (sometimes Wolf shift) is a frequency shift in the electromagnetic spectrum. The phenomenon occurs in several closely related phenomena in radiation physics, with analogous effects occurring in the scattering of light. It was first predicted by Emil Wolf in 1987 and subsequently confirmed in the laboratory in acoustic sources by Mark F. Bocko, David H. Douglass, and Robert S. Knox, and a year later in optic sources by Dean Faklis and George Morris in 1988.
Theoretical description
In optics, two non-Lambertian sources that emit beamed energy can interact in a way that causes a shift in the spectral lines. It is analogous to a pair of tuning forks with similar frequencies (pitches), connected together mechanically with a sounding board; there is a strong coupling that results in the resonant frequencies getting "dragged down" in pitch. The Wolf Effect requires that the waves from the sources are partially coherent - the wavefronts being partially in phase. Laser light is coherent while candlelight is incoherent, each photon having random phase. It can produce either redshifts or blueshifts, depending on the observer's point of view, but is redshifted when the observer is head-on.
For two sources interacting while separated by a vacuum, the Wolf effect cannot produce shifts greater than the linewidth of the source spectral line, since it is a position-dependent change in the distribution of the source spectrum, not a method by which new frequencies may be generated. However, when interacting with a medium, in combination with effects such as Brillouin scattering it may produce distorted shifts greater than the linewidth of the source.
Notes
- Emil Wolf, "Selected Works of Emil Wolf: With Commentary" (2001) p.638, ISBN 981-02-4204-2.
- James, Daniel F V (1998). "The Wolf effect and the redshift of quasars". Pure and Applied Optics: Journal of the European Optical Society Part A. 7 (5). IOP Publishing: 959–970. arXiv:astro-ph/9807205. Bibcode:1998PApOp...7..959J. doi:10.1088/0963-9659/7/5/006. ISSN 0963-9659. S2CID 17670250.
- ^ Wolf, Emil (1987). "Non-cosmological redshifts of spectral lines". Nature. 326 (6111). Springer Science and Business Media LLC: 363–365. Bibcode:1987Natur.326..363W. doi:10.1038/326363a0. ISSN 0028-0836. S2CID 4337925.
- Wolf, Emil (1987). "Redshifts and blueshifts of spectral lines caused by source correlations". Optics Communications. 62 (1). Elsevier BV: 12–16. Bibcode:1987OptCo..62...12W. doi:10.1016/0030-4018(87)90057-5. ISSN 0030-4018.
- Bocko, Mark F.; Douglass, David H.; Knox, Robert S. (1987-06-22). "Observation of frequency shifts of spectral lines due to source correlations". Physical Review Letters. 58 (25). American Physical Society (APS): 2649–2651. Bibcode:1987PhRvL..58.2649B. doi:10.1103/physrevlett.58.2649. ISSN 0031-9007. PMID 10034809.
- Faklis, Dean; Morris, G. Michael (1988-01-01). "Spectral shifts produced by source correlations". Optics Letters. 13 (1). The Optical Society: 4—6. Bibcode:1988OptL...13....4F. doi:10.1364/ol.13.000004. ISSN 0146-9592. PMID 19741961.
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