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arXiv 2108.07288astro-ph.GAastro-ph.HE
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3C 273在150 MHz的分辨喷流

The resolved jet of 3C 273 at 150 MHz

Jeremy J. Harwood, Sean Mooney, Leah K. Morabito, John Quinn, Frits Sweijen, Christian Groeneveld, Etienne Bonnassieux, Alexander Kappes, Javier Moldon

备注：
Accepted to a special issue of A&A on sub-arcsecond imaging with LOFAR. 13 pages, 10 figures, 2 tables
发表信息：
A&A 658, A8 (2022)
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摘要：

自1963年发现以来，3C 273已成为研究最广泛的类星体之一，研究范围涵盖电磁波谱。虽然关于这个历史上著名的来源已经发现了很多，但它的低频发射远没有那么好理解。在MHz范围内的观测传统上缺乏探索小尺度结构所需的分辨率，而小尺度结构是理解导致观测到的发射的过程的关键。在本文中，我们使用的第一个亚弧秒图像的3C 273在MHz的频率，调查的形态紧凑的喷流结构和过程，导致观察到的频谱。使用LOFAR的国际站的全部补充，我们产生$0.31 \times 0.21$ arcsec图像的3C 273在150 MHz，以确定喷流的动力学功率，放置约束的批量速度和倾斜角的喷流，并寻找证据的难以捉摸的反喷流在150 MHz。在GHz频率的辅助数据，我们拟合自由-自由吸收（FFA）和同步辐射自吸收（SSA）模型，以确定其有效性解释所观察到的光谱。所展示的图像首次显示，使用LOFAR国际基线，现在可以对低赤纬复杂源进行稳健、高保真的成像。我们发现，3C 273的主要小尺度结构匹配那些在较高的频率和吸收是存在于所观察到的发射。我们确定喷流的动能在$3.5 \times 10^{43}$ - $1.5 \times 10^{44}$ erg s $^{-1}$的范围内，这与使用更高频率观测所作的估计一致。我们分别推导了$β\gtrsim 0.55$和$Γ\geq 1.2$的体速度和洛伦兹因子的下限。在$150$ MHz下，反喷流仍然未被检测到，这对$S_\mathrm{cj\_150} < 40$ mJ γ束$^{-1}$的峰值亮度施加了限制。

英文摘要：

Since its discovery in 1963, 3C273 has become one of the most widely studied quasars with investigations spanning the electromagnetic spectrum. While much has been discovered about this historically notable source, its low-frequency emission is far less well understood. Observations in the MHz regime have traditionally lacked the resolution required to explore small-scale structures that are key to understanding the processes that result in the observed emission. In this paper we use the first sub-arcsecond images of 3C273 at MHz frequencies to investigate the morphology of the compact jet structures and the processes that result in the observed spectrum. Using the full complement of LOFAR's international stations, we produce $0.31 \times 0.21$ arcsec images of 3C273 at 150 MHz to determine the jet's kinetic power, place constraints on the bulk speed and inclination angle of the jets, and look for evidence of the elusive counter-jet at 150 MHz. Using ancillary data at GHz frequencies, we fit free-free absorption (FFA) and synchrotron self-absorption (SSA) models to determine their validity in explaining the observed spectra. The images presented display for the first time that robust, high-fidelity imaging of low-declination complex sources is now possible with the LOFAR international baselines. We show that the main small-scale structures of 3C273 match those seen at higher frequencies and that absorption is present in the observed emission. We determine the kinetic power of the jet to be in the range of $3.5 \times 10^{43}$ - $1.5 \times 10^{44}$ erg s$^{-1}$ which agrees with estimates made using higher frequency observations. We derive lower limits for the bulk speed and Lorentz factor of $β\gtrsim 0.55$ and $Γ\geq 1.2$ respectively. The counter-jet remains undetected at $150$ MHz, placing a limit on the peak brightness of $S_\mathrm{cj\_150} < 40$ mJy beam$^{-1}$.

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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