AI 中文总结
该研究利用南极望远镜SPT-3G的毫米波观测，首次系统搜寻blazars毫米波EVPA摆动，发现其与伽马射线耀发存在部分关联，且现有随机游走模型无法解释观测到的摆动特性。
AI 中文摘要
我们利用南极望远镜（South Pole Telescope）的SPT-3G相机在95和150 GHz波段五年的观测数据，首次对blazars毫米波（mm-wave）辐射中的电矢量位置角（EVPA）摆动进行系统搜寻，并探究其与伽马射线耀发的关联。在约1500平方度的SPT-3G主天区中的168个亮源里，8个拥有足够的偏振信噪比以进行可靠的EVPA测量，其中4个有费米LAT卫星的连续伽马射线探测。我们在所有4个伽马射线活跃的blazars中均探测到EVPA摆动，而在其余4个中未探测到，这与光学波段已确立的EVPA摆动和高能辐射的关联一致。观测到的摆动振幅和旋转速率小于光学研究中的结果，符合毫米波EVPA变率比短波长更慢的结论。采用多胞模型的偏振角随机游走模拟无法同时复现观测到的摆动数量、振幅和持续时间，表明该机制不足以解释观测到的摆动群体。对一周时标上的EVPA变率分析与光学波段先前观测到的偏振度与EVPA旋转速率的反相关一致。在14个探测到的摆动中，8个出现在伽马射线耀发的30天内。尽管许多单个摆动-耀发关联的偶然发生概率极低，但95和150 GHz波段摆动相对于伽马射线耀发的时间滞后整体集合符合随机巧合。
英文摘要
We present the first systematic search for electric vector position angle (EVPA) swings in the millimeter-wave (mm-wave) emission of blazars, using five years of observations from the South Pole Telescope SPT-3G camera at 95 and 150 GHz, and investigate their connection to gamma-ray flares. Of the 168 bright sources in the ~1500 square degrees SPT-3G Main Field, eight have sufficient polarization signal-to-noise for reliable EVPA measurement, four of which have continuous Fermi LAT gamma-ray detections. We detect EVPA swings in all four gamma-ray-active blazars and in none of the remaining four, consistent with the established connection between EVPA swings and high-energy emission seen at optical wavelengths. The observed swing amplitudes and rotation rates are smaller than those found in optical studies, consistent with mm-wave EVPA variability being slower than at shorter wavelengths. Random walk simulations of the polarization angle using a multi-cell model fail to reproduce both the number, amplitude, and duration of the observed swings, suggesting that this mechanism is insufficient to explain the observed swing population. Analysis of EVPA variability on one-week timescales is consistent with the anti-correlation between polarization degree and EVPA rotation rate previously observed at optical wavelengths. Of the 14 detected swings, eight are within 30 days of a gamma-ray flare. While many individual swing-flare associations are found to have a very low probability of happening by chance, the full ensembles of 95 and 150 GHz swing time lags with respect to gamma-ray flares are found to be consistent with random coincidence.
CommentsTo be submitted to ApJ
