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arXiv 2205.02808astro-ph.HEastro-ph.GA
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Blazar VER J0521 +211在高TeV Gamma-Ray状态期间的多波长观测

Multiwavelength Observations of the Blazar VER J0521+211 During an Elevated TeV Gamma-Ray State

The VERITAS Collaboration, The MAGIC Collaboration

摘要:

我们报告了VERITAS,MAGIC和Fermi-LAT在2013年和2014年观测到的VER J 0521 +211的长期,高伽马射线通量状态。在200 GeV以上的峰值积分通量是$(8.8 \pm 0.4) \times 10^{-7} \;\text{ph}\;\text{m}^{-2}\; \text{s}^{-1}$,约为蟹状星云通量的37%。还介绍了X射线、紫外线和光学仪器的多波长观测结果。观察到X射线和TeV γ射线通量之间的适度相关性,并且当通量较高时,X射线谱出现更硬。利用伽玛射线谱和河外背景光(EBL)的四种模型,发现源红移的保守95%置信上限为z<=0.31。与伽马射线和X射线波段不同,在研究期间,光通量与存档的低态通量相比没有显着增加。从光学到X射线波段的光谱可变性表明,光谱能量分布(SED)的同步峰值在耀斑状态期间可能会变得更宽,这可以用改变底层粒子光谱的高能端的单区同步自康普顿模型来充分描述。同步辐射峰值频率的SED,以及从MOJAVE程序的射流的无线电形态,是一致的源是一个中频峰值BL湖对象。

英文摘要:

We report on a long-lasting, elevated gamma-ray flux state from VER J0521+211 observed by VERITAS, MAGIC, and Fermi-LAT in 2013 and 2014. The peak integral flux above 200 GeV measured with the nightly-binned light curve is $(8.8 \pm 0.4) \times 10^{-7} \;\text{ph}\;\text{m}^{-2}\; \text{s}^{-1}$, or ~37% of the Crab Nebula flux. Multiwavelength observations from X-ray, UV, and optical instruments are also presented. A moderate correlation between the X-ray and TeV gamma-ray fluxes was observed, and the X-ray spectrum appeared harder when the flux was higher. Using the gamma-ray spectrum and four models of the extragalactic background light (EBL), a conservative 95% confidence upper limit on the redshift of the source was found to be z<=0.31. Unlike the gamma-ray and X-ray bands, the optical flux did not increase significantly during the studied period compared to the archival low-state flux. The spectral variability from optical to X-ray bands suggests that the synchrotron peak of the spectral energy distribution (SED) may become broader during flaring states, which can be adequately described with a one-zone synchrotron self-Compton model varying the high-energy end of the underlying particle spectrum. The synchrotron peak frequency of the SED, as well as the radio morphology of the jet from the MOJAVE program, are consistent with the source being an intermediate-frequency-peaked BL Lac object.

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