[论文解读] Investigating the origin of radio emission in candidate super-Eddington accreting black holes

Marie-Lou Gendron-Marsolais, Paola Marziani+9 more|arXiv (Cornell University)|Jan 30, 2026

Astrophysical Phenomena and Observations被引用 0

一句话总结

该研究使用多波段射电（VLA、LOFAR、VLASS）和红外数据对18个xA类准星体进行分析，以判断其射电辐射是由星体形成还是与AGN相关过程主导，结果显示混合情况，若干为SF主导，且少数同时存在超Eddington吸积与相对论喷射。

ABSTRACT

Recent works show that the radio power of quasars accreting at very high rates can reach surprisingly high values. These studies suggest that this radio emission might originate from star formation, but lack of data leaves open the possibility that they could also contain a jetted active galactic nucleus (AGN). We investigate the origin of the radio emission of a sample of 18 super-Eddington candidates, over a wide range of redshifts. These sources are expected to have extreme radiative output per unit black hole mass, show high-velocity outflows and are therefore thought to be a prime mover of galactic evolution via radiative and mechanical feedback. We present new Karl G. Jansky Very Large Array (VLA) observations at L, C and X-band of these sources, which we combine with observations from the LOw-Frequency ARray (LOFAR) Two-metre Sky Survey (LoTSS) and the Very Large Array Sky Survey (VLASS). We also use optical and IR data to derive estimates of accretion and wind parameters, as well as star formation rates to compare with the ones derived from the radio emission. Based on the radio variability, luminosity, morphology, radio spectral properties, radio vs IR estimates of star formation rate and radio-to-mid IR flux ratio, we find that 7 of our 18 targets are likely to have their radio emission predominantly coming from SF, and 6 from a combination of SF and AGN-related mechanisms, while only three sources indicate a core or jetted AGN only origin for the detected radio emission. This is consistent with previous studies, and supports the prevalence of lower power radio structures associated with star-forming activity rather than relativistic jets in the high Eddington ratio regime. In the same sample, however, we find three sources for which the data suggest a concomitant presence of super-Eddington accretion and relativistic ejections.

研究动机与目标

• 评估18个xA（高Fe II）准星体样本的射电辐射是否主要来自星体形成还是AGN相关的外流/喷射。
• 将VLA、LOFAR和VLASS射电数据与光学/IR测量结合，以估算吸积、风和星形成参数。
• 对射电形态和谱特性进行分类，以推断每个源的主导发射机制。

提出的方法

• 用VLA在L、C和X带（1.5、5、10 GHz）对18个xA类准星体进行观测，并用LOFAR LoTSS（144 MHz）和VLASS（3 GHz）补充。
• 用CASA数据处理，进行宽带成像，并应用自校准与宽带主波束修正。
• 从多带通量计算谱指数，推导射电光度与Kellermann R_K 值，比较射电与中红外通量比（Q22）及SFR指示量。
• 用峰值/总通量比定义射电形态，将其分类为Compact、Intermediate或Extended。
• 从IR光度估算SFR，并使用已建立的标定（如Kennicutt）将射电推导的SFR进行比较。

Figure 1: Prevalence of FIRST-detected type-1 AGN (Marziani et al. , 2013 ) (blue circles and cyan shading) and median radio power (red circles and rose shading) as a function of spectral type along the quasar main sequence.

实验结果

研究问题

• RQ1 xA类准星体中，射电辐射有多少比例来自星体形成与AGN相关过程？
• RQ2 射电形态、谱指数以及射电-红外诊断是否能区分SF主导与喷射主导的超Eddington候选对象？
• RQ3 是否存在同时具有超Eddington吸积与相对论喷射的源？
• RQ4 xA对象的射电活动如何与它们在准星序列上的位置及Eddington比相关？

主要发现

• 18个目标中有7个的射电辐射主要来自星体形成。
• 6个源显示星体形成与AGN相关机制共同贡献射电辐射的混合特征。
• 3个源表明检测到的射电辐射源于核心或喷射（仅AGN）。
• 有三条源显示同时存在超Eddington吸积与相对论喷射的证据。
• 在LOFAR频率下看起来扩展性更高，而大多数高频数据较为紧凑。
• 射电-中红外诊断总体上并未将整个样本置于blazar域，大多数源并非由射电喷射主导。

Figure 2: Radio morphology distribution across the redshifts of the sources. C indicates compact at all frequencies observed, I is intermediate morphology detected in at least one band, and E indicates the presence of diffuse emission in at least one band.