Redshift and radio magnitude of quasars

1987

Astron Nachr

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Strong emission lines may change the brightness of QSOs and hence their observed magnitudes. Since different lines will affect the magnitudes by entering a particular filter at different redshifts. this effect may alter the number of QSOs at a particular redshift and hence the redshift distribution. The present analysis shows that the influence of the emission lines on the U and B magnitudes are significantly correlated to the redshift distribution. I t is concluded that the changes in observed magnitudes of QSOs caused by the emission lines have significant effects on the present redshift distribution.Starke Emissionslinien konnen die Helligkeit von Quasaren und folglich die beobachtete GroBenklasse verandern. D a die einzelnen Linien sich auf die Helligkeit, je nach dem benutzten Filter und der Rotverschiebung, auswirken werden, kann dies die Zahl der QSO bei bestimmten Rotverschiebungen beeinflussen. Die vorliegende Analyse zeigt, daB der EinfluB von Emissionslinien auf die U-und B-Helligkeiten mit der Rotverschiebungsverteilung signifikant korreliert ist. Daraus wird der SchluD abgeleitet, daB die Veriinderungen in den beobachteten QSO-Helligkeiten, die durch Emissionslinien bedingt sind, signifikante Auswirkungen auf dic gegenwartig zu beobachtende Rotverschiebungsverteilung haben. K q ' words: quasars -redshift distributionThe importance of observational effects on the physical interpretation of the QSO redshift distribution is now well recognized and a number of such effects are already established (ROEDER 1971 ; ROEDER and DYER 1972;BASU 1973BASU , 1975 BASU , 1978BASU , 1983BASU , 1985. However several authors (KJAEGAARD 1978; KODYACHIKH 1979;DEPAQUIT and PECKER 1985;WAMPLER and PONZ 1985) have suggested yet another selection effect, viz., the effect of strong emission lines in changing the brightness of QSOs and hence their observed magnitudes. As different lines will affect the magnitude by entering a particular filter at different redshifts, this effect may alter the number of QSOs observed at a certain redshift and hence the redshift distribution. However, the suggestions referred to above are of purely qualitative nature and no statistical analysis has yet been carried out to test it.It is obvious that any such test must include the effect of the emission lines on all the three filters, viz. U , B and V at which magnitudes are evaluated. MCCREA (1966), KARDASHEV and KOMBERC (19661, SANDAGE (19661, STRITTMATTER and BURBIDCE ( 1967) Considering the importance of the effect mentioned above from cosmological point of view, we were prompted to analyse the present data thoroughly with a view to find out whether the emission lines influence the observed magnitudes of QSOs so as to affect the redshift distribution.We considered the effects of influence of all the emission lines observed in the QSO spectrum, falling within all the three U, B, V filters, with proper "weights", rather than very strong lines only. The "weight" being functions of strength, width and frequency of occurence of a line as report...

Section: K Q ' Words: Quasars -Redshift Distributionmentioning

confidence: 93%

Section: K Q ' Words: Quasars -Redshift Distributionmentioning

confidence: 96%

mentioning

confidence: 99%

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Effect of changes in magnitudes of QSO_s in their redshift distribution

1987

Astron Nachr

Self Cite

“…Existence of periodicities in the redshift (Þ) distribution of QSOs has been claimed since a long time (Burbidge & Burbidge 1967;Cowan 1969;Lake & Roeder 1972;Burbidge & O'Dell 1972;Barnothy & Barnothy 1976;Karlsson 1977Karlsson , 1990Arp et al 1990), while peaks and troughs in the Þ-distribution that are responsible for exhibiting periodicities have also been shown to be due to the presence of various selection effects (Basu 1973(Basu , 1975(Basu , 1978a(Basu , 1978b(Basu , 1985(Basu , 1992(Basu , 1999Willy & Ricklefs 1976;Box & Roeder 1984;Scott 1991). These studies include samples involving the total number of QSOs known at that time, as well as individual samples of QSOs spanning limited redshift ranges.…”

Section: Introductionmentioning

confidence: 99%

“…Basu (1973Basu ( , 1975, on the other hand, introduced two selection effects, viz. the availability of search lines in measuring redshifts of QSOs (A × ) and the effect of emission lines entering U, B filters in changing the color index of a QSO ((U-B) Ä ) resulting in the object being mistaken as an MS star.…”

Section: Introductionmentioning

confidence: 99%

Periodicity versus selection effects in the redshift distribution of QSOs

2001

Astron. Nachr.

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Periodicities and selection effects in the redshift (z) distribution of QSOs have been debated for a long time in the literature. Here we show that peaks and troughs in the redshift distribution of three new samples, claimed to demonstrate the existence of a periodicity, can be interpreted in terms of known selection effects. This analysis confirms earlier findings that the presence of such selection effects seriously weakens any suggestion for periodicity of the form Δl n (1 + z) = constant.

Periodicity versus selection effects in the redshift distribution of QSOs

2001

Astron. Nachr.

Self Cite

Periodicities and selection effects in the redshift (Þ) distribution of QSOs have been debated for a long time in the literature. Here we show that peaks and troughs in the redshift distribution of three new samples, claimed to demonstrate the existence of a periodicity, can be interpreted in terms of known selection effects. This analysis confirms earlier findings that the presence of such selection effects seriously weakens any suggestion for periodicity of the form ¡ Ð Ò ½ · Þ µ ÓÒ×Ø Ò Ø .