高红移类星体与候选体最内侧喷流的总辐射与偏振辐射：秒差距尺度分辨率下的研究
The Total and Polarized Radio Emission from the Innermost Jets of a High-Redshift Quasar and a Candidate at Parsec-Scale Resolution
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中文总结 AI 辅助
该研究利用22 GHz欧洲VLBI网络观测高红移类星体J1510+5702及候选体J1606+3124，测得其喷流亮温度、偏振度等参数，表明厘米波VLBI可探测高红移喷流的静止帧毫米波偏振。
中文摘要 AI 辅助
高频甚长基线干涉测量（VLBI）偏振测量可探测射电噪活动星系核（AGN）中心引擎附近的同步辐射等离子体，但43 GHz以上的观测技术要求极高。我们报告了22 GHz欧洲VLBI网络对红移z=4.31的类星体J1510+5702及J1606+3124的观测结果，其中J1606+3124已发布的光谱红移z=4.56存在不确定性，测光估计给出z_phot=0.9±0.1。若采用已发布的z>4红移，22 GHz对应静止帧频率高于118 GHz。在J1510+5702中探测到偏振辐射，从J1606+3124最亮的特征中恢复出低水平偏振信号。采用z=4.56时，该特征的VLBI亮温度T_b,VLBI=(7.4±0.8)×10^10 K，可采用适度多普勒增强的解释，而年轻致密源的场景仍可行。J1510+5702的核的VLBI亮温度T_b,VLBI=(1.08±0.15)×10^12 K，在 equipartition 假设下意味着多普勒因子约为22，该成分的偏振度约为3.5%。这些观测表明，厘米波VLBI可探测到明亮z>4喷流中的静止帧毫米波偏振。
英文摘要
High-frequency very long baseline interferometry (VLBI) polarimetry probes synchrotron-emitting plasma closer to the central engines of radio-loud active galactic nuclei (AGNs), but observations above 43 GHz are technically demanding. We present 22-GHz European VLBI Network observations of the $z=4.31$ quasar J1510+5702 and J1606+3124, whose published spectroscopic redshift, $z=4.56$, is uncertain; a photometric estimate gives $z_{\rm phot}=0.9\pm0.1$. For the published $z>4$ redshifts, 22 GHz corresponds to rest-frame frequencies above 118 GHz. Polarized emission is detected in J1510+5702, and a low-level polarized signal is recovered from the brightest feature of J1606+3124. Adopting $z=4.56$, that feature has a brightness temperature of $T_{\mathrm{b,VLBI}}=(7.4\pm0.8)\cdot10^{10}$ K, allowing a mildly Doppler-boosted interpretation, while the young compact-source scenario also remains viable. The core of J1510+5702 has $T_{\mathrm{b,VLBI}}=(1.08\pm0.15) \cdot10^{12}$ K, implying a Doppler factor of ${\sim}22$ under the equipartition assumption. This component has a ${\sim}3.5$ % fractional polarization. These observations show that cm-wavelength VLBI can access rest-frame millimeter-band polarization in bright $z>4$ jets.
