Redshift asymmetries are found in almost all samples of paired galaxies with precise redshifts

Redshift asymmetries are found in almost all samples of paired galaxies with precise redshifts

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Redshift asymmetries are found in almost all samples of paired galaxies with precise redshifts, especially where spirals are involved. The tendency is for the fainter galaxy to have a slightly larger redshift, with a peak in the distribution at 50-80 km/s. The form of the distribution suggests that this is independent of background contamination. Conventional explanations have focussed on problem in measuring redshifts of dusty rotating disks (for example, if dust is stronger on the inside or outside of arms, the nuclear velocity may be distorted) or, for small groups, on expansion and perspective effects in unbound groupings (Byrd and Valtonen 1985 APJ 289, 535; 1986 ApJ 303, 523). This problem is not directly related to AGN, but letting one camel's nose into the Hubble tent might weaken its defenses for other applications. Detailed study of how one measures redshifts from optical spectra in complicated velocity fields shows that some of this effect comes from the different weightings of continuum and emission-line radiation (Keel 1996 ApJS 106, 27). Tifft has claimed that redshift differences in galaxy pairs are quantized , with intervals from 12- 72 km/s depending on sample size (Tiffy 1982 ApJ 257, 442; 257, 442, for example). Such an effect must nullify velocity Doppler shifts since, under conventional dynamics, they would smear
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This note was uploaded on 11/10/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.

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Redshift asymmetries are found in almost all samples of paired galaxies with precise redshifts

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