A polarimetric study of 9 PG quasars with the VLA
A polarimetric study of 9 PG quasars with the VLA
复制标题
用 VLA 对 9 个 PG 类星体进行偏振研究
DOI：
10.1093/mnras/stac3691
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发表时间：
2022
影响因子：
4.8
通讯作者：
Baghel J
中科院分区：
文献类型：
--
作者：
Baghel J
我们展示了来自 6 GHz VLA B 阵列的 9 个射电响 (RL) 类星体的偏振图像。这些类星体属于 Palomar-Green (PG)“耀变体”样本，由 16 个 RL 类星体和 8 个 BL Lac 天体组成。在所有类星体的核心、喷流和叶瓣中都检测到了广泛的极化，核心主要显示横向于喷流方向的磁场（B-），而喷流则显示与喷流方向对齐的磁场。热点显示横向 B 场（表示末端冲击时的 B 场压缩）或更复杂的结构。纤芯的分数极化范围为 1% 至 10%，射流/波瓣的范围为 10% 至 40%。一些类星体显示出扭曲或混合的 FRI/FRII 射电形态，表明银河核活动重新开始。我们将此归因于 PG 样品的光学/紫外选择标准在射频下保持无偏差。无线电核心的带内频谱指数相对平坦，而在热点区域则陡峭。这与极化结构一致，其中热点似乎是射流弯曲或弓形激波的位置。我们展示了整个 PG ‘blazar’ 样本的全局属性。我们发现喷射功率与类星体的吸积率相关。更高的吸积率会产生更强大的射电喷流。这里研究的九个类星体的射电核心分数极化和 150 MHz 总射电光度之间的相关性可能意味着射流基座上更有组织的 B 场会导致更高的核心分数极化和更强大的射电射流。
We present polarization images of nine radio-loud (RL) quasars from the VLA B-array at 6 GHz. These quasars belong to the Palomar-Green (PG) ‘blazar’ sample comprising 16 RL quasars and eight BL Lac objects. Extensive polarization is detected in the cores, jets, and lobes of all the quasars, with cores primarily displaying magnetic (B-) fields transverse to, and jets displaying fields aligned with the jet direction. Hotspots display either transverse B-fields signifying B-field compression at terminal shocks or more complex structures. The fractional polarization in the cores ranges from 1 per cent to 10 per cent and jets/lobes from 10 per cent to 40 per cent. Several of the quasars show distorted or hybrid FRI/FRII radio morphologies with indications of restarted active galactic nucleus activity. We attribute this to the optical/UV selection criteria of the PG sample that remains unbiased at radio frequencies. The in-band spectral indices of the radio cores are relatively flat, while they are steep in the hotspots. This is consistent with the polarization structures where the hotspots appear to be locations of jet bends or bow-shocks. We present global properties for the entire PG ‘blazar’ sample. We find that jet powers correlate with accretion rates for the quasars; higher accretion rates result in more powerful radio jets. A correlation between the radio core fractional polarization and the 150 MHz total radio luminosity for the nine quasars studied here may imply that more organized B-fields at the jet bases lead to higher core fractional polarization and to more powerful radio jets.
AGN 加油：观测角度
DOI：
--
发表时间：
2002
期刊：
影响因子：
--
作者：
Francoise Combes
通讯作者：
Francoise Combes
Nrao 的天文图像处理系统 (AIPS)
DOI：
--
发表时间：
1985
期刊：
影响因子：
--
作者：
D. Wells
通讯作者：
D. Wells