Multi-band optical variability of 3C 279 on diverse timescales

AGARWAL, A.; CELLONE, S. A.,; ANDRUCHOW, I.; MAMMANA, L. A.; SINGH, M.; ANUPAMA, G. C.; MIHOV, B.; ASHISH RAJ; SLAVCHEVA-MIHOVA, L.; OZDONMEZ, A.; ERGUN, E.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2019 vol. 488 p. 4093 - 4105

0035-8711

We have monitored the FSRQ 3C 279 in the optical B, V, R and I passbands from February 2018 to July 2018 for 24 nights, with a total of ∼ 716 frames, to study flux, colour and spectral variability on diverse timescales. 3C 279 was observed using seven different telescopes: two in India, two in Argentina, two in Bulgaria and one in Turkey to understand the nature of the source in optical regime. The source was found to be active during the whole monitoring period and displayed significant flux variations in B, V, R, and I passbands. Variability amplitudes on intraday basis varied from 5.20% to 17.9%. A close inspection of variability patterns during our observation cycle reveals simultaneity among optical emissions from all passbands. During the complete monitoring period, progressive increase in the amplitude of variability with frequency was detected for our target. The amplitudes of variability in B,V,R and I passbands have been estimated to be 177%, 172%, 171% and 158% respectively. Using the structure function technique, we found intraday timescales ranging from ∼72 minutes to about 202 minutes. We also studied colour-magnitude relationship and found indications of mild bluer-when-brighter trend on shorter timescales. Spectral indices ranged from 2.3 to 3.0 with no clear trend on long term basis. We have also generated spectral energydistributions for 3C 279 in optical B, V, R and I passbands for 17 nights. Finally, possible emission mechanisms causing variability in blazars are discussed briefly.