Multiwavelength Observations of Markarian 501 during the 1997 High State
Multiwavelength Observations of Markarian 501 during the 1997 High State
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1997 年高态期间 Markarian 501 的多波长观测
DOI：
10.1086/308955
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
M. Villata
中科院分区：
文献类型：
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作者：
D. Petry;M. Böttcher;V. Connaughton;A. Lähteenmäki;T. Pursimo;C. Raiteri;F. Schroeder;A. Sillanpää;G. Sobrito;L. Takalo;H. Teräsranta;G. Tosti;M. Villata
在1997年的观测期间，附近的耀变体Mrk 501表现出极强的辐射和高变异性。我们使用无线电、光学、软、硬x射线和TeV数据来研究这一事件的多波长方面。我们专注于宽带光谱的中时间尺度变异性，平均每周的间隔。我们证实了先前发现的软x射线和硬x射线发射与TeV能量发射之间的相关性，而源在射电和光波长的变化很小。硬x射线和TeV通量之间的非线性相关性与基于SSC模型的简单分析估计一致，其中Klein-Nishina效应对射流中最高能量的电子很重要，通量的变化是由电子密度和/或电子注入谱指数的变化引起的。时间平均光谱采用同步加速器自康普顿（SSC）主导的轻子射流模型，使用完整的Klein-Nishina横截面，并遵循相对论粒子沿射流的自一致演化，考虑源内的γγ吸收和对产生以及由于星系间红外背景辐射。外部逆康普顿散射的贡献受到最大EGRET通量较低的严格约束，在TeV能量下可以忽略不计。我们发现，高水平的x射线和TeV通量可以用喷流底部注入的电子能谱的硬化来解释，这与平谱射电类星体PKS 0528+134的γ射线耀斑的趋势形成鲜明对比。
During the observation period 1997, the nearby blazar Mrk 501 showed extremely strong emission and high variability. We examine multiwavelength aspects of this event using radio, optical, soft and hard X-ray, and TeV data. We concentrate on the medium-timescale variability of the broadband spectra, averaged over weekly intervals. We confirm the previously found correlation between soft and hard X-ray emission and the emission at TeV energies, while the source shows only minor variability at radio and optical wavelengths. The nonlinear correlation between hard X-ray and TeV fluxes is consistent with a simple analytic estimate based on an SSC model in which Klein-Nishina effects are important for the highest-energy electrons in the jet, and flux variations are caused by variations of the electron density and/or the spectral index of the electron injection spectrum. The time-averaged spectra are fitted with a synchrotron self-Compton (SSC) dominated leptonic jet model, using the full Klein-Nishina cross section and following the self-consistent evolution of relativistic particles along the jet, accounting for γγ absorption and pair production within the source as well as due to the intergalactic infrared background radiation. The contribution from external inverse-Compton scattering is tightly constrained by the low maximum EGRET flux and found to be negligible at TeV energies. We find that high levels of the X-ray and TeV fluxes can be explained by a hardening of the energy spectra of electrons injected at the base of the jet, in remarkable contrast to the trend found for γ-ray flares of the flat-spectrum radio quasar PKS 0528+134.