Variability of extragalactic objects in relation to redshift, color, radio spectral index and absorption lines |
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Authors: | D Basu |
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Institution: | (1) Department of Physics, Carleton University, K1S 5B6 Ottawa, ON, Canada |
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Abstract: | Optical variability of extragalactic objects, viz., QSOs, BL Lacs and Seyfert galaxies has been monitored systematically over
an appreciable period of time and a large amount of data have accumulated. The present work reports results of investigations
involving statistical analysis of updated data on relationships between variability and various observed properties of the
objects, viz., redshift, color indices, radio spectral index and absorption lines. It is found that at high frequencies (rest
frame) radio spectral index does not change significantly with the degree of variability. However, the degree of variability
depends on redshifts. On the other hand, presence or absence of absorption lines is significantly associated with variability
for QSOs with larger redshifts (z > 1.0), while no such relationship exists for QSOs at smaller redshifts (z < 1.0) or other objects. Correlation between color indices and redshifts depends on the degree of variability and the sample
chosen for the color index. |
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Keywords: | Galaxies active: galaxies quasars: general |
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