发表机构
Texas Tech University; INAF - Osservatorio Astronomico di Brera（德州理工大学; 意大利国家天体物理研究所-布雷拉天文台）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究报道了早期活动星系核在37 GHz的极端射电变异性，振幅变化达三至四个数量级，可能源于黑洞附近的相干辐射，而非相对论性喷流。
AI 中文摘要
我们报告了在早期活动星系核（AGN）中发现的极端37 GHz射电变异性。这些源中的大多数属于窄线 Seyfert 1（NLS1）星系类别，该类星系拥有快速增长、低质量的超大质量黑洞，并以高爱丁顿比率吸积。在37 GHz频率下，这些非凡的AGN在几天的时间尺度上表现出三到四个数量级的振幅变化。值得注意的是，尽管进行了多次尝试，我们未在这些源中探测到相对论性喷流，这表明该现象可能发生在非常靠近黑洞的区域，并可能代表一种新的AGN变异性形式。其中一个在37 GHz发生耀发的源，随后用卡尔·G·詹斯基甚大阵列和Swift XRT/UVOT进行了跟进观测。基于这些观测，我们估计了仅数小时的e折叠时间尺度，导致变异性亮温度和变异性多普勒因子极难用非相干辐射体来解释。这表明可能探测到了来自AGN的相干辐射，尽管还需要更多观测来区分其他可能的解释。
英文摘要
We report the discovery of extreme 37 GHz radio variability in early-stage active galactic nuclei (AGN). Most of these sources belong to the class of narrow-line Seyfert 1 (NLS1) galaxies, which harbour fast-growing, low-mass supermassive black holes that accrete at high Eddington ratios. At 37 GHz, these extraordinary AGN exhibit amplitude variability of three to four orders of magnitude over timescales of a few days. Notably, despite several attempts, we have not detected relativistic jets in these sources, suggesting that this phenomenon may occur very close to the black hole and may represent a new form of AGN variability. One of these sources, which flared at 37 GHz, was followed up with the Karl G. Jansky Very Large Array and Swift XRT/UVOT. Based on these observations, we estimated an e-folding timescale of mere hours, leading to variability brightness temperatures and variability Doppler factors that are extremely difficult to explain by an incoherent emitter. This suggests a possible detection of coherent emission from an AGN, although more observations will be needed to distinguish between alternative scenarios.
Comments5 pages, proceedings for the conference ZIHUAGN Redemption: central kpc region, Zihuatanejo, Gro., Mexico, October 27-31, 2025. Accepted for publication on Revista Mexicana de Astronomía y Astrofísica
