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arXiv 1504.03136astro-ph.HE
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Gamma-ray活动耀变体的5年全球3毫米VLBI巡天

5 year Global 3-mm VLBI survey of Gamma-ray active blazars

J. A. Hodgson, T. P. Krichbaum, A. P. Marscher, S. G. Jorstad, I. Marti-Vidal, M. Lindqvist, M. Bremer, S. Sanchez, P. de Vicente, J. A. Zensus

摘要:

全球毫米VLBI阵列(GMVA)是一个由14台3.5毫米和7.5毫米望远镜组成的网络,覆盖欧洲和美国,并计划扩展到亚洲。该阵列能够敏感地图的角分辨率往往超过50\,$μ$作为。利用GMVA,从2008年晚些时候到现在,大约每6个月观测到一个大样本的显著的$γ$射线耀变体。结合GMVA的3,mm图、VLBA-BU-BLAZAR程序的近时7,mm图和MOJAVE程序的2,cm图,确定了$γ$射线耀变体的亚pc形态和高频谱结构。在磁场和相对论粒子能量均分的假设下,可以估计沿射流不同位置处的磁场强度。假设喷流磁场结构(例如极向或环形),我们可以估计毫米波“核心”和喷流底部的分离,并估计那里的磁场强度。该分析的结果表明,平均而言,磁场强度以幂律$B \propto r^{-n}$、$n=0.3 \pm 0.2$减小。这表明,平均而言,毫米波“核心”是去投影射流顶点下游的$\sim 1-3$ \,pc,并且磁场强度是$B_{\rm{apex}} \sim 5-20$ \,kG的量级,与磁射流发射的预测大致一致(例如,经由磁制动盘(MAD))。

英文摘要:

The Global mm-VLBI Array (GMVA) is a network of 14 3\,mm and 7\,mm capable telescopes spanning Europe and the United States, with planned extensions to Asia. The array is capable of sensitive maps with angular resolution often exceeding 50\,$μ$as. Using the GMVA, a large sample of prominent $γ$-ray blazars have been observed approximately 6 monthly from later 2008 until now. Combining 3\,mm maps from the GMVA with near-in-time 7\,mm maps from the VLBA-BU-BLAZAR program and 2\,cm maps from the MOJAVE program, we determine the sub-pc morphology and high frequency spectral structure of $γ$-ray blazars. The magnetic field strength can be estimated at different locations along the jet under the assumption of equipartition between magnetic field and relativistic particle energies. Making assumptions on the jet magnetic field configuration (e.g. poloidal or toroidal), we can estimate the separation of the mm-wave "core" and the jet base, and estimate the strength of the magnetic field there. The results of this analysis show that on average, the magnetic field strength decreases with a power-law $B \propto r^{-n}$, $n=0.3 \pm 0.2$. This suggests that on average, the mm-wave "core" is $\sim 1-3$\,pc downstream of the de-projected jet apex and that the magnetic field strength is of the order $B_{\rm{apex}} \sim 5-20$\,kG, broadly consistent with the predictions of magnetic jet launching (e.g. via magnetically arrested disks (MAD)).

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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