天文学进展2011，Vol.29Issue(1)：86-96,11.
3C 454.3伽玛射线和近红外辐射延时分析
Analysis for Time Lag Between γ-ray and NIR Variations in 3C 454.3
摘要
Abstract
Discrete Correlation Function (DCF) is a powerful tool to analyze correlation between two sets. A kind of the progressive DCF technique, time-transformed DCF (TDCF),is used to analyze time lag between variations of γ-ray and J or B bands for 3C 454.3. The TDCFs of Fermi/LAT γ-ray vs SMARTS J and B bands light curves both peak at (T) = -1.66 days. This implies that γ-ray variations lead the J band ones by about 2 days. The period of the data is from JD=2 454 710 to JD=2 454 770. Considering the effects of flux errors and sampling characteristics, FR, RSS and the combined of them are used to Monte Carlo simulations to estimate the time lags and the uncertainties. The simulations show that the γ-rays lead the J band emission. Thus it is reliable that the γ-rays lead the J band emission. The time lag might be due to the cooling time-scale of electrons' synchrotron and Compton radiations. In this case, the energy of ‘seed' photons couldn't be higher than 1.1 eV. The time lag also might be related to the different sizes of their emission regions. The strong correlation of the two variations indicates that the γ-rays and the J band emission are emitted from the same region. As a shock spreads in the region, it first influences the whole γ-ray emission region. At this time, the γ-ray flux reaches its maximum value. The inner -ray emission region is only a part of the NIR emission region. Thus the NIR flux has not reached its maximum value as the γ-rays reach the maximum. As the shock spreads the whole NIR emission region, a few days later, the NIR flux reaches its maximum.Time-scale of variations indicates the size of an emission region. The structure functions show that the timescale of the J band variations is larger than that of the γ-rays, about 2 days. This timescale difference of about 2 days is consistent with the time lag of the J band emission relative to the γ-rays. This agreement supports the above explanation of the time lag. Around JD(≈)2 454 712, both the γ-rays and the optical B band emission show their minimum flux, which also supports the above explanation.关键词
类星体/3C 454.3/延时Key words
quasars/ 3C 454.3/ time lag分类
天文与地球科学引用本文复制引用
李少昆,白金明,刘洪涛,张晋,陈亮..3C 454.3伽玛射线和近红外辐射延时分析[J].天文学进展,2011,29(1):86-96,11.基金项目
国家自然科学基金项目(10903025,10973034,11078008) （10903025,10973034,11078008）
科技部973项目(2009CB824800) （2009CB824800）
中科院西部之光人才培养计划博士项目 （）
