Enhanced Polarized Emission from the One-parsec-scale Hotspot of 3C 84 as a Result of the Interaction with the Clumpy Ambient Medium
Enhanced Polarized Emission from the One-parsec-scale Hotspot of 3C 84 as a Result of the Interaction with the Clumpy Ambient Medium
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DOI：
10.3847/1538-4357/aa8e43
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发表时间：
2017-09
期刊：
影响因子：
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通讯作者：
H. Nagai;Y. Fujita;M. Nakamura;M. Orienti;M. Kino;K. Asada;G. Giovannini
中科院分区：
文献类型：
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作者：
H. Nagai;Y. Fujita;M. Nakamura;M. Orienti;M. Kino;K. Asada;G. Giovannini
本文介绍了在43 GHz频率上对3C 84（NGC 1275）最内层喷流的甚长基线阵列偏振观测。一个显着的偏振发射检测在热点的最里面的重新启动喷流，这是位于1 pc南从无线电核心。虽然上一份报告在西翼的南端提出了一个热点，但热点位置已被移至东翼的南端。在43 GHz频带的整个带宽内检测法拉第旋转。测得的自转测量值（RM）最多为（6.3 ± 1.9）× 105 rad m−2，并且在一个月的时间尺度上可能会有轻微的时间变化。我们测得的RM和RM先前报告的CARMA和SMA观测不能一致地解释球形吸积流与幂律配置文件。我们建议，cluberous/不均匀的环境介质是负责所观察到的RM。使用均分磁场，我们导出电子密度为2 × 104 cm−3。这样的电子密度与中心发动机周围的窄线发射区域的云是一致的。我们还讨论了从黑洞尺度到秒差距尺度的磁场位形和低极化的起源。
We present Very Long Baseline Array polarimetric observations of the innermost jet of 3C 84 (NGC 1275) at 43 GHz. A significant polarized emission is detected at the hotspot of the innermost restarted jet, which is located 1 pc south from the radio core. While the previous report presented a hotspot at the southern end of the western limb, the hotspot location has been moved to the southern end of the eastern limb. Faraday rotation is detected within an entire bandwidth of the 43 GHz band. The measured rotation measure (RM) is at most (6.3 ± 1.9) × 105 rad m−2 and might be slightly time variable on the timescale of a month by a factor of a few. Our measured RM and the RM previously reported by the CARMA and SMA observations cannot be consistently explained by the spherical accretion flow with a power-law profile. We propose that a clumpy/inhomogeneous ambient medium is responsible for the observed RM. Using an equipartition magnetic field, we derive the electron density of 2 × 104 cm−3. Such an electron density is consistent with the cloud of the narrow line emission region around the central engine. We also discuss the magnetic field configuration from the black hole scale to the parsec scale and the origin of low polarization.