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    • Keywords


      Accretion, accretion disks; galaxies: active; galaxies: nuclei; quasars: general.

    • Abstract


      Optical variability is an important feature of quasars. Taking advantage of a larger sample of 7658 quasars from SDSS Stripe 82 and relatively more photometric data points for each quasar, we estimate their variability amplitudes and divide the sample into small bins of various parameters. An anticorrelation between variability amplitude and rest-frame wavelength is found. Variability increases as either luminosity or Eddington ratio decreases. The relationship between variability and black hole mass is uncertain. The intrinsic distribution of variability amplitudes for radio-loud and radio-quiet quasars are different. Both radio-loud and radio-quiet quasars exhibit a bluer-when-brighter chromatism. With the Shakura–Sunyaev disk model, we find that changes of accretion rate play an important role in producing the observed optical variability. However, the predicted positive correlation between variability and black hole mass seems to be inconsistent with the observed negative correlation between them in small bins of Eddington ratio, which suggests that other physical mechanisms may still need to be considered in modifying the simple accretion disk model. The different mechanisms in radio-loud and radio-quiet quasars are discussed.

    • Author Affiliations


      Wenwen Zuo1 Xue-Bing Wu1 Yi-Qing Liu1 Cheng-Liang Jiao2

      1. Department of Astronomy, Peking University, Beijing 100871, China.
      2. Korea Astronomy and Space Science Institute, Daejeon, South Korea.
    • Dates

  • Journal of Astrophysics and Astronomy | News

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      Posted on January 27, 2016

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