Optical Variability Properties of High Luminosity AGN Classes

Journal of astrophysics and astronomy

C. S. Stalin1 2¹  Ram Sagar¹  Gopal-Krishna³  Paul J. Wiita² 

[1] Aryabhatta Research Institute of Observational Sciences (ARIES), Manora Peak Nainital 263 129, India.$$;Department of Physics & Astronomy, MSC 8R0314, Georgia State University, Atlanta, Georgia 30303-3088, USA.$$;National Centre for Radio Astrophysics, TIFR, Pune University Campus, Pune 411 007, India.$$

关键词: Galaxies: active;    galaxies: jets;    galaxies: photometry;    quasars: general.;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

We present the results of a comparative study of the intra-night optical variability (INOV) characteristics of radio-loud and radio-quiet quasars, which involves a systematic intra-night optical monitoring of seven sets of high luminosity AGNs covering the redshift range 𝑧 ≃ 0.2 to 𝑧 ≃ 2.2. The sample, matched in the optical luminosity – redshift (𝑀𝐵-𝑧) plane, consists of seven radio-quiet quasars (RQQs), eight radio lobe-dominated quasars (LDQs), five radio core-dominated quasars (CDQs) and six BL Lac objects (BLs). Systematic CCD observations, aided by a careful data analysis procedure, have allowed us to detect INOV with amplitudes as low as about 1%. Present observations cover a total of 113 nights (720 hours) with only a single qusar monitored as continuously as possible on a given night. Considering the cases of only unambiguous detections of INOV we have estimated duty cycles (DCs) of 17%, 12%, 20% and 61% for RQQs, LDQs, CDQs, and BLs, respectively. The much lower amplitude and DC of INOV shown by RQQs compared to BLs may be understood in terms of their having optical synchrotron jets which are modestly misdirected from us. From our fairly extensive dataset, no general trend of a correlation between the INOVamplitude and the apparent optical brightness of the quasar is noticed. This suggests that the physical mechanisms of INOV and long term optical variability (LTOV) do not have a one-to-one relationship and different factors are involved. Also, the absence of a clear negative correlation between the INOV and LTOV characteristics of blazars of our sample points toward an inconspicuous contribution of accretion disk fluctuations to the observed INOV. The INOV duty cycle of the AGNs observed in this program suggests that INOV is associated predominantly with the highly polarized optical emission components. We also report new VLA imaging of two RQQs (1029 + 329 & 1252 + 020) in our sample which has yielded a 5 GHz detection in one of them (1252 + 020; 𝑆5GHz ≃ 1 mJy)

【 授权许可】

Unknown