We report on a multiwavelength campaign on the TeV γ-ray blazar Mrk 421 performed during 2002 December and 2003 January. These target of opportunity observations were initiated by the detection of X-ray and TeV γ-ray flares with the All Sky Monitor (ASM) on board the Rossi X-Ray Timing Explorer (RXTE) and the 10?m Whipple γ-ray telescope. The campaign included observational coverage in the radio (University of Michigan Radio Astronomy Observatory), optical (Boltwood, La Palma KVA 0.6 m; WIYN 0.9 m), X-ray (RXTE pointed telescopes), and TeV γ-ray (Whipple and HEGRA) bands. At TeV energies, the observations revealed several flares at intermediate flux levels, peaking between 1 and 1.5 times the flux from the Crab Nebula. While the time-averaged spectrum can be fitted with a single power law of photon index Γ = 2.8 from dNγ/dE ∝ E-Γ, we find some evidence for spectral variability. Confirming earlier results, the campaign reveals a rather loose correlation between the X-ray and TeV γ-ray fluxes. In one case, a very strong X-ray flare is not accompanied by a comparable TeV γ-ray flare. Although the source flux was variable in the optical and radio bands, the sparse sampling of the optical and radio light curves does not allow us to study the correlation properties in detail. We present a simple analysis of the data with a synchrotron self-Compton model, emphasizing that models with very high Doppler factors and low magnetic fields can describe the data.
展开▼
机译：我们报道了在2002年12月和2003年1月期间对TeVγ射线Blazar Mrk 421进行的多波长运动。这些机会观察的目标是通过在Rossi X射线定时探测器（RXTE）和10？m Whippleγ射线望远镜上使用全天候监视仪（ASM）检测X射线和TeVγ射线耀斑来启动的。这项运动包括在无线电（密歇根大学射电天文台），光学（博尔特伍德，拉帕尔玛KVA 0.6 m; WIYN 0.9 m），X射线（RXTE指向望远镜）和TeVγ射线（Whipple和HEGRA）的观测范围。 ）乐队。在TeV能量下，观测发现在中等通量水平上出现了几处耀斑，峰值在蟹状星云通量的1到1.5倍之间。虽然时间平均光谱可以根据dNγ/ dE ∝E-Γ拟合光子指数Γ= 2.8的单次幂定律，但我们发现了光谱可变性的一些证据。该活动证实了较早的结果，揭示了X射线和TeVγ射线通量之间存在相当松散的相关性。在一种情况下，非常强的X射线耀斑并没有可比的TeVγ射线耀斑。尽管源通量在光学和无线电频带中是可变的，但是光学和无线电光曲线的稀疏采样不允许我们详细研究相关特性。我们用同步加速器自康普顿模型对数据进行简单分析，强调具有非常高的多普勒因子和低磁场的模型可以描述数据。
展开▼
