Long-Term multiband monitoring of blazar 3C 66A: Evidence of the two distinct states with different baseline flux

Krishna Mohana A, Debbijoy Bhattacharya, Ranjeev Misra, Subir Bhattacharyya, Nilay Bhatt

Research output: Contribution to journalArticlepeer-review

Abstract

Blazar variability can be described as flaring activities on a wide range of time-scales over a baseline flux level. It is important to detect and distinguish baseline flux changes from long-Term flare variations, since the former may reflect state transitions caused by a secular change in bulk properties such as the bulk Lorentz factor or the viewing angle. We report such a transition observed in the 11 yr Fermi γ-ray light curve of the blazar 3C 66A, where the baseline flux of ∼1.8 × 10-7 ph cm-2 s-1 persisted for three years and then changed over a month time-scale to ∼0.8 × 10-7ph cm-2s-1 and remained in that level for the next eight years. Moreover, there is evidence for a similar shift in baseline flux in the optical band. Broad-band spectral energy distribution modelling for the two activity states reveals that the baseline flux change is consistent with an overall decrease in the Doppler factor, which in turn implies an increase in the jet inclination angle by ∼1° or a decrease in the bulk Lorentz factor by ∼25 per cent. We discuss the implication of such a variation occurring on a month time-scale.

Original languageEnglish
Pages (from-to)3653-3659
Number of pages7
JournalMonthly Notices of the Royal Astronomical Society
Volume507
Issue number3
DOIs
Publication statusPublished - 01-11-2021

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Fingerprint

Dive into the research topics of 'Long-Term multiband monitoring of blazar 3C 66A: Evidence of the two distinct states with different baseline flux'. Together they form a unique fingerprint.

Cite this