用ATCA和VLASS观测窄线Seyfert 1星系的射电谱
Radio spectra of narrow-line Seyfert 1 galaxies observed with ATCA and VLASS
摘要：
我们提出了一个样本的29无线电安静（RQ）和无线电响亮（RL）窄线塞弗特1星系（NLS 1 s）检测与澳大利亚望远镜紧凑阵列在5.5 GHz和9.0 GHz的射电光谱分析。样品的特征在于L_bol/L_Edd > 0.15。在29个RQ NLS 1中，有25个的射电斜率较陡（α_5.5 -9.0 < -0.5），这与早先对RQ高L_bol/L_Edd活动星系核的研究结果一致。这种陡峭的射电辐射可能与活动星系核驱动的外流有关，这种外流在高L_bol/L_Edd活动星系核中可能更为普遍。在三个RL NLS 1中的两个中，射电斜率是平坦的或反向的（α_5.5 -9.0 > -0.5），表明一个紧凑的光学厚源，可能是相对论性喷流。在3.0 GHz，1.4 GHz和0.843 GHz的存档数据也被编译，产生一个样本的17个NLS 1在三个频段或更多的检测。在9个天体中，无线电频谱在较低频率处变平，中值斜率为α_5.5 -9.0 = -1.21 +/- 0.17，变平到α_3.0 -5.5 = -0.97 +/- 0.27和α_1.4 -3.0 = -0.63 +/- 0.16。一个抛物线拟合表明一个中位数的频谱营业额为1 GHz，这意味着同步自吸收源的大小只有一小部分的1 pc，可能是一个紧凑的风或弱喷流。两个物体在3 GHz或5 GHz以上显示出显著的光谱陡化，α < -2，这可能表明过去几年到几十年前的射电发射等离子体喷射的遗迹发射。最后，两个天体呈现出与恒星形成活动一致的单一光谱斜率。
英文摘要：
We present radio spectral analyses for a sample of 29 radio-quiet (RQ) and three radio-loud (RL) narrow-line Seyfert 1 galaxies (NLS1s) detected with the Australia Telescope Compact Array at both 5.5 GHz and 9.0 GHz. The sample is characterized by L_bol/L_Edd > 0.15. The radio slopes in 25 of the 29 RQ NLS1s are steep (alpha_5.5-9.0 < -0.5), as found in earlier studies of RQ high L_bol/L_Edd AGN. This steep radio emission may be related to AGN-driven outflows, which are likely more prevalent in high L_bol/L_Edd AGN. In two of the three RL NLS1s, the radio slopes are flat or inverted (alpha_5.5-9.0 > -0.5), indicating a compact optically-thick source, likely a relativistic jet. Archival data at 3.0 GHz, 1.4 GHz, and 0.843 GHz are also compiled, yielding a sample of 17 NLS1s detected in three bands or more. In nine objects, the radio spectra flatten at lower frequencies, with median slopes of alpha_5.5-9.0 = -1.21 +/- 0.17, flattening to alpha_3.0-5.5 = -0.97 +/- 0.27, and to alpha_1.4-3.0 = -0.63 +/- 0.16. A parabolic fit suggests a median spectral turnover of ~ 1 GHz, which implies synchrotron self-absorption in a source with a size of only a fraction of 1 pc, possibly a compact wind or a weak jet. Two objects show significant spectral steepening to alpha < -2 above 3 GHz or 5 GHz, which may suggest relic emission from past ejection of radio emitting plasma, of the order of a few years to a few decades ago. Finally, two objects present a single spectral slope consistent with star-forming activity.
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