发表机构
Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR), Universität Heidelberg; Department of Physics and Astronomy, Georgia State University; Institut für Theoretische Physik, Universität Heidelberg; CP3-Origins, University of Southern Denmark; Department of Astronomy, University of Maryland, College Park（海德堡大学跨学科科学计算中心; 佐治亚州立大学物理与天文系; 海德堡大学理论物理研究所; 南丹麦大学CP3起源研究中心; 马里兰大学帕克分校天文学系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过多频段VLBA观测分析J0011+3443，结合谱特性等证据支持其为GPS类致密对称天体，暂无法排除双活动星系核的可能。
AI 中文摘要
我们呈现了对天体J0011+3443（TXS 0008+344，红移z=0.89）的新的多频段甚长基线阵列（VLBA）观测结果，观测频段包括2.3、4.9、8.5 GHz，以及首次观测的23.6 GHz。该源由两个致密成分A和B组成，投影间距为314±2 pc，此外在23.6 GHz频段探测到第三个特征C，位于A的0.6角秒处。存档的低分辨率射电测量结果证实其具有积分的千兆赫峰谱，观测帧的峰值频率ν_peak=0.73±0.08 GHz，峰值流量密度S_peak=879±125 mJy。与频率匹配度较高的低分辨率测量结果对比显示，VLBA恢复了4.85 GHz流量密度的0.85±0.11，以及8.46 GHz流量密度的0.50±0.06。8.5 GHz处较低的恢复比例表明，低表面亮度辐射被分辨出去或低于VLBA的表面亮度灵敏度，因此我们将VLBA成分谱解释为仅致密恢复辐射的谱。23.6 GHz的形态、未探测到平坦谱核、A和B的致密谱相似，以及积分千兆赫谱较陡，这些特征支持将J0011+3443解释为GPS类致密对称天体，可能处于短寿命或遗迹阶段，不过若无多历元天体测量，无法排除双活动星系核的起源。
英文摘要
We present new multi-frequency VLBA observations of J0011+3443 (TXS 0008+344, z = 0.89) at 2.3, 4.9, 8.5, and, for the first time, 23.6 GHz. The source consists of two compact components A and B at a projected separation of 314 +/- 2 pc, plus a third feature C detected at 23.6 GHz at 0.6 mas from A. Archival low-resolution radio measurements confirm an integrated gigahertz-peaked spectrum, with an observed-frame peak frequency of 0.73 +/- 0.08 GHz and a peak flux density of 879 +/- 125 mJy. Comparison with nearly frequency-matched low-resolution measurements shows that the VLBA recovers 0.85 +/- 0.11 of the 4.85 GHz flux density and 0.50 +/- 0.06 of the 8.46 GHz flux density. The lower recovered fraction at 8.5 GHz suggests that low-surface-brightness emission is resolved out or falls below the VLBA surface-brightness sensitivity. We therefore interpret the VLBA component spectra as spectra of the compact recovered emission only. The 23.6 GHz morphology, the absence of a detected flat-spectrum core, the similar compact spectra of A and B, and the steep integrated GHz spectrum favor an interpretation of J0011+3443 as a GPS-class compact symmetric object, possibly in a short-lived or relic phase, although a dual-AGN origin cannot be excluded without multi-epoch astrometry.
Comments8 pages, 3 figures, 3 tables. Accepted for publication in A&A
