AI 中文总结
研究SDSS J1548+2208这个部分遮挡核瞬变源，通过多波长观测发现其爆发六年后中红外、X射线通量仍处高通量水平，射电频谱能量分布异常，有再增亮及可能新耀斑迹象，用新生外流冲击介质解释其特性，为相关研究提供新见解。
AI 中文摘要
SDSS J1548+2208是一个独特的部分遮挡核瞬变源，在中红外、X射线和射电波段呈现多波长爆发。我们展示了自发现以来约2500天的多波长光度和光谱后续观测结果。发现中红外和X射线发射（硬X射线谱）仍处于相对于耀斑前状态的高通量水平，暗示中央黑洞吸积活动突然增加且可能长期持续，高电离日冕线缓慢演化也支持此点。中红外颜色在上升阶段缓慢变蓝，与恒星潮汐瓦解事件不同。射电频谱能量分布异常，有双峰特征和独特变化特性。还发现初始爆发六年多后射电再增亮及可能新的X射线耀斑迹象。其奇特的射电通量和SED演化可用新生外流冲击核周弥漫介质解释。SDSS J1548+2208是能发射射电外流的罕见可变型活动星系核。持续多波长观测有助于绘制pc尺度上的尘埃和气体分布，为调节活动星系核可变现象的环境特性提供新见解。
英文摘要
SDSS J1548+2208 is a unique partially-obscured nuclear transient that exhibits multiwavelength outbursts in mid-infrared, X-ray and radio. We present the results from multiwavelength photometric and spectroscopic follow-up observations with a time span of ~2500 days since its discovery. We find that the mid-infrared and X-ray emission (with a hard X-ray spectrum) are still in a high flux level relative to the pre-flare state, suggesting a sudden increased, and possibly long-sustained accreting activity from central black hole. This is supported by the slowly-evolving high-ionization coronal lines. The mid-infrared color turns blue slowly in the rising phase, which is distinct from stellar tidal disruption events (TDEs). All these properties point to the origin of outbursts from an extreme changing-look AGN and the scenario with a normal TDE seems disfavored. The radio spectral energy distribution (SED) in ~0.65-15 GHz is unusual, displaying a double-peak feature with distinct variability characteristics. In addition, we find evidence for the late-time radio rebrightening more than six years since the initial outburst, as well as a possibly new X-ray flare, though the significance for the latter is not high. The peculiar radio flux and SED evolution could be explained by a nascent outflow expanding into and shocking circumnuclear diffuse medium filled by denser clouds. In this case, SDSS J1548+2208 represents a rare changing-look AGN which can launch radio outflows. Continued multiwavelength observations are required to map the dust and gas distribution on pc-scales, providing new insights into the environmental properties that could regulate AGN changing-look phenomenon.
CommentsPublished in ApJ, 24 pages, 6 main figures
Journal refApJ, 1006, 6 (2026)
