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    • Variability of extragalactic objects in relation to redshift, color, radio spectral index and absorption lines

      D. Basu

      Volume 22 Issue 4 December 2001 pp 263-282

    • Fulltext

       

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      Permanent link:
      https://www.ias.ac.in/article/fulltext/joaa/022/04/0263-0282

    • Keywords

       

      Galaxies active: galaxies; quasars: general

    • 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.

    • Author Affiliations

       

      D. Basu1

      1. Department of Physics, Carleton University, Ottawa, ON - K1S 5B6, Canada

    • Dates

       
      Published
      December 2001
      Manuscript received
      13 November 2000
      Accepted
      11 December 2001

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