论文标题
无线电未定的类星体中堆叠的无线电排放的起源是什么？
What is the origin of the stacked radio emission in radio-undetected quasars?: Insights from a radio-infrared image stacking analysis
论文作者
论文摘要
最明亮的无线电类星体中的无线电发射可以归因于SMBH固有的过程，而无线电检测的数量中无线电通量的起源仍然不确定。我们研究了$ 9.3 \：\ textrm {deg}^{2} $ ndwfs-boortes field; RUQ是类星体，由Lofar在$ \geq5σ$上单独发现。我们使用了中位图像堆叠过程。这是以150 MHz，325 MHz，1.4 GHz和3.0 GHz的频率完成的，在$ 8 $至500 \;μ\μ\ textrm {M} $之间进行了9个红外（IR）频段。无线电和红外光度法使我们能够在$ 0 <z <6.15 $之间得出四个Z bin的RDQ和RUQ的中值光谱分布。使用SF星系的FAR-IR无线电相关性（FIRC）将IR星形形成率（SFR）与两个独立的无线电恒星形成（SF）示踪剂进行比较。我们发现我们的无线电和IR SFR测量与FIRC预测之间有很好的一致性。此外，我们使用FIRC预测来建立由于SMBH积聚对总射线luminition（RL）而产生的贡献。我们表明，SMBH积聚可以占中位RUQ的总RL的$ \ sim5-41 \％$，而对于中间RDQ，贡献为$ \ sim50-84 \％$。这意味着剧烈的SF活性与我们堆叠的类星体中位数中的SMBH生长是共同的。此外，我们研究了Radio-Loudness参数，$ r $。对于具有$ r \ geq-4.5 $的类星体，RL与由SMBH积聚支配的RL是一致的，而对于$ r <-4.5 $的低RL类星体，SF对无线电通量的相对贡献随着SMBH组件的相对贡献而增加。我们还发现，在150 MHz的最亮RDQ中，AGN反馈负反馈的标志。最后，我们发现类星体的光谱指数随着Z的变化并没有显着发展，但它们会朝着较低的频率变化。
Radio emission in the brightest radio quasars can be attributed to processes inherent to SMBHs, while the origins of the radio fluxes in quasars without radio detections is still uncertain. We investigate the radio-infrared continuum of LOFAR radio-detected quasars (RDQs) and LOFAR radio-undetected quasars (RUQs) in the $9.3\:\textrm{deg}^{2}$ NDWFS-Boötes field; RUQs are quasars that are individually undetected at $\geq5σ$ by LOFAR. We used a median image stacking procedure. This was done in the frequencies of 150 MHz, 325 MHz, 1.4 GHz and 3.0 GHz, and in nine infrared (ir) bands between $8$ and $500\;μ\textrm{m}$. The radio and ir photometry allow us to derive the median spectral energy distributions of RDQs and RUQs in four z-bins between $0<z<6.15$. The ir star-formation rate (SFR) is compared with two independent radio-based star-formation (SF) tracers using the far-ir radio correlation (FIRC) of SF galaxies. We find a good agreement between our radio and ir SFR measurements and the FIRC predictions. Moreover, we use the FIRC predictions to establish the contribution due to SMBH accretion to the total radio-luminosity (RL). We show that SMBH accretion can account for $\sim5-41\%$ of the total RL in median RUQs, while for median RDQs the contribution is $\sim50-84\%$. This implies that vigorous SF activity is coeval with SMBH growth in our median stacked quasars. Furthermore, we investigated the radio-loudness parameter, $R$. For quasars with $R\geq-4.5$, the RL is consistent with being dominated by SMBH accretion, while for low RL quasars with $R<-4.5$ the relative contribution of SF to the radio fluxes increases as the SMBH component becomes weaker. We also find signatures of negative AGN feedback in the brightest median RDQs at 150 MHz. Finally, we found that spectral indices of quasars do not evolve significantly with z, but they become flatter towards lower freqs.
