The flat spectrum radio quasar 3C 279 was observed in an extremely high activity state on June 16, 2015 (MJD 57189). In this paper, we investigate the properties of this flaring episode in the high energy γ-ray and optical bands using data from the Fermi-LAT, SMARTS, and SPOL observations during the period June 1-30, 2015 (MJD 57174-57203). The highest emission state in the γ-ray band detected by the Fermi-LAT exhibits a peak flux of ∼ 2×10⁻⁷ erg cm⁻² s⁻¹ which is more than 25 times the flux level measured in the low activity state of the source. The temporal analysis of the daily Fermi-LAT light curve suggests that the giant flaring episode has characteristic rise and decay times less than one day. The optical daily light curves in B, V, R, and J bands also indicate the flaring activity from 3C 279 with flux levels peaking for two days on June 16-17, 2015 (MJD 57189-57190). The discrete correlation function analysis indicates a time lag of 1 day or longer between the γ-ray and optical peaks during the flaring episode. The γ-ray emission is also observed to show a harder-when-brighter behaviour whereas optical emission exhibits an opposite behaviour. The γ-ray emission region during the flare is observed to be very compact and is located close to the base of the jet. The degree of linear polarization in the wavelength range 500-700 nm measured using SPOL during this period is also highly variable with a peak of ∼ 30% one day after the γ-ray flare. Near simultaneous γ-ray flux points show a linear anti-correlation with the degree of polarization during the period of γ-ray flare. The significant drop in the degree of linear polarization suggests a sudden increase in the tangled magnetic field strength in the emission region.

2015年6月16日，在超高活动状态下观测到了平面频谱类星体3C 279（MJD 57189）。在本文中，我们使用2015年6月1日至30日（MJD 57174-57203）的费米-LAT，SMARTS和SPOL观测数据，研究了高能γ射线和光学带中这种爆发现象的性质。费米-LAT探测到的γ射线波段的最高发射态呈现出约2×10 ^-7 erg cm ^-2 s ^-1的峰值通量，大于在低活性态下测量的通量水平的25倍。来源。每日费米的时间分析-LAT光曲线表明，巨大的爆发事件具有少于一天的特征上升和下降时间。B，V，R和J波段的每日光学光曲线还表明3C 279的燃烧活动，通量水平在2015年6月16日至17日连续两天达到峰值（MJD 57189-57190）。离散相关函数分析表明，在爆发期间，γ射线和光学峰之间存在1天或更长时间的时滞。该γ射线发射，也观察到显示一个更难时-亮行为而光学发射显示出相反的行为。该γ观察到耀斑中的射线发射区域非常紧凑，并且位于射流的底部附近。在此期间，使用SPOL在500-700 nm波长范围内测得的线性偏振度也是高度可变的，在γ射线爆发后的一天达到30％的峰值。在γ射线耀斑期间，几乎同时出现的γ射线通量点与偏振度呈线性反相关。线性极化程度的显着下降表明发射区域中纠缠的磁场强度突然增加。