失配还是混沌？利用VLT/FORS2偏振光谱学揭示本地LRD J1025中轴对称性的强破缺
Misaligned or chaotic? A strong break of axial symmetry in the local LRD J1025 revealed with VLT/FORS2 spectropolarimetry
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中文总结 AI 辅助
研究利用VLT/FORS2偏振光谱观测发现本地LRD J1025存在显著的偏振角偏移，证实其内部轴对称性破缺，对现有LRD模型提出挑战并探讨未来观测方向。
中文摘要 AI 辅助
小红点（LRDs）是具有不寻常光谱能量分布和宽巴耳末发射的致密活动星系核（AGN），是黑洞快速增长的候选标志。我们利用VLT/FORS2对已知最近的LRD SDSS J102530.29+140207.3（红移z=0.1）开展光学线性偏振光谱观测。在总光中，我们探测到空间延展的窄Hα发射，可能追踪到寄主星系。测得近灰色连续谱偏振度p_cont=1.53±0.04（随机误差）±0.20（系统误差）%，而宽Hα偏振度更低，为p_Hα=0.58-0.84%。我们排除了银河系尘埃偏振及非偏振谱线的稀释作用。这种带退偏振谱线的偏振连续谱与本地赛弗特1型核相似，支持单主导源而非多源解释。扣除斯托克斯连续谱后，宽Hα未出现蓝到红的摆动，但偏振角存在显著的（48±4）°的连续谱-谱线偏移，这意味着该天体内部存在轴对称性破缺，对现有所有LRD模型和框架构成有趣的几何挑战。我们讨论了这种对称性破缺的不同可能起源，以及未来观测区分这些起源的可能路径。
英文摘要
Little Red Dots (LRDs) are compact active galactic nuclei (AGN) with unusual spectral energy distributions and broad Balmer emission, candidate signposts of rapid black-hole growth. We present VLT/FORS2 optical linear spectropolarimetry of the closest known LRD, SDSS J102530.29+140207.3, at z=0.1. In total light, we detect spatially extended narrow-H$α$ emission, probably tracing the host galaxy. We measure a nearly grey continuum polarisation $p_{\rm cont}=1.53\pm0.04$(rand.)$\pm$0.20(syst.) per cent, while broad H$α$ is less polarised, $p_{\rm Hα}=0.58-0.84$ per cent. We rule out polarisation by Milky Way dust and dilution by an unpolarised line. The polarised continuum with a depolarised line resembles local Seyfert-1 nuclei and favours a single dominant source over multi-source explanations. After Stokes-continuum subtraction, broad H$α$ shows no blue-to-red swing, but there is a significant (48$\pm$4)$^\circ$ continuum-to-line offset in polarisation angle. This implies a break of axial symmetry inside this object, posing interesting geometrical challenges to all existing LRD models and frameworks. We discuss different possible origins of this symmetry break and possible paths to discriminate between them with future observations.
