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m Merged two paragraphs about SDSS. Redundant to say it's probably not selection effects and then it is selection effects in the next paragraph. |
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:"... fit very closely the long standing Karlsson formula and strongly suggest the existence of preferred values in the distribution of quasar redshifts."<ref>{{cite journal| last1=Arp| first1=H.| last2=Fulton| first2=C.| last3=Roscoe| first3=D.| title=Periodicities of Quasar Redshifts in Large Area Surveys|date=2005|arxiv=astro-ph/0501090 |bibcode = 2005astro.ph..1090A }}</ref>
A 2006 study of 46,400 quasars in the [[Sloan Digital Sky Survey|SDSS]] by Bell and McDiarmid discovered 6 peaks in the redshift distribution consistent with the decreasing intrinsic redshift (DIR) model.<ref name="adsabs.harvard.edu"/> However, Schneider ''et al.'' (2007) and Richards ''et al.'' (2006)
▲Schneider ''et al.'' (2007) and Richards ''et al.'' (2006) report that the periodicity reported by Bell and McDiarmid disappears after correcting for selection effects.<ref>{{cite journal | last1 = Schneider | display-authors =etal | date=2007| title = The Sloan Digital Sky Survey Quasar Catalog. IV. Fifth Data Release| bibcode=2007AJ....134..102S | journal = The Astronomical Journal | volume = 134 | issue = 1| pages = 102–117 |doi = 10.1086/518474 |arxiv = 0704.0806 | s2cid =14359163 }}</ref><ref>{{cite journal | last1 = Richards | first1 = G. T. | display-authors =etal | date=2006| title = The Sloan Digital Sky Survey Quasar Survey: Quasar Luminosity Function from Data Release 3| journal = The Astronomical Journal | volume = 131 | issue = 6 | pages = 2766–2787 |doi = 10.1086/503559 |arxiv = astro-ph/0601434 | bibcode=2006AJ....131.2766R| s2cid = 55346862 }}</ref> However, Bell and Comeau (2010) have since argued that this correction removes nearly half of the sample and does not explain how selection effects give rise to redshift peaks. The same study also concludes that a "filter gap footprint" renders it impossible to verify or falsify the presence of a true redshift peak at Δ''z'' = 0.60.<ref>{{cite journal | last1 = Bell| first1 = M. B. | last2 = Comeau | first2 = S. P. | date=2010| title = Selection Effects in the SDSS Quasar Sample: The Filter Gap Footprint| journal = Astrophys Space Sci | volume = 326 | issue = 1| pages = 11–17 |doi = 10.1007/s10509-009-0232-2 |arxiv = 0911.5700 |bibcode = 2010Ap&SS.326...11B | s2cid = 118655062 }}</ref>
A 2006 review by Bajan ''et al.'' discovered weak effects of redshift periodization in data from the [[Local Group]] of galaxies and the [[Hercules Supercluster]]. They conclude that "galaxy redshift periodization is an effect which can really exist", but that the evidence is not well established pending study of larger databases.<ref>{{cite journal |bibcode=2007PPNL....4....5B|arxiv=astro-ph/0606294 | title=On the Investigations of Galaxy Redshift Periodicity | journal=Physics of Particles and Nuclei Letters |date=2007 |volume=4 |issue=1 |pages=5–10 |first1=K. |last1=Bajan |first2=P. |last2=Flin |first3=W. |last3=Godlowski |first4=V. N. |last4=Pervushin |doi=10.1134/s1547477107010025|s2cid=15364493 }}</ref>
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