发表机构
Durham University; University of Edinburgh; University of Hertfordshire（杜伦大学; 爱丁堡大学; 赫特福德大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究结合布茨天区深观测，分析红移0.3至2的2840个射电AGN，发现LERG的X射线吸积性质显著弱于HERG和RQ-AGN，且两类辐射的产生过程可能不耦合。
AI 中文摘要
我们结合布茨天区的深射电与X射线观测，表征了射电探测活动星系核（AGN）的吸积率性质。我们利用国际LOFAR望远镜的深观测，在红移0.3 < z ≤ 2范围内识别出2840个射电AGN，划分成射电光度完备的样本，并进一步将该样本分为四类：射电宁静AGN（RQ-AGN）、高激发射电星系（HERG），以及由恒星形成星系（SF-LERG）和宁静星系（Q-LERG）寄主的低激发射电星系（LERG）。通过X射线堆叠分析，我们测定了平均X射线光度$L_{\rm{X, 2-10 keV}}$和平均比X射线光度$\lambda_{sL_{X}}$（按恒星质量归一化的X射线光度，作为吸积率的 proxy），并研究了这四类AGN的X射线性质如何依赖于射电光度、恒星质量和红移。我们发现，无论恒星形成活动如何，LERG在所有红移下的$L_{\rm{X, 2-10 keV}}$和$\lambda_{sL_{X}}$均显著低于HERG和RQ-AGN；HERG、RQ-AGN和SF-LERG的平均X射线光度通常随红移增加而上升，这可能与早期冷气体占比更高、黑洞吸积更剧烈有关；在给定红移下，平均X射线光度与射电光度呈弱相关或无相关，表明产生X射线和射电辐射的物理过程在空间和/或时间尺度上可能并不耦合。
英文摘要
We characterise the accretion rate properties of radio-detected AGN by combining deep radio and X-ray observations of the Boötes field. We used deep international LOFAR telescope observations to identify 2840 radio-AGN across $0.3 < z \leq 2$, divided into samples that are complete in radio luminosity. We further split this sample into four different classes: radio-quiet AGN (RQ-AGN), high-excitation radio galaxies (HERGs), and low-excitation radio galaxies (LERGs) hosted by star-forming (SF-LERGs) and quiescent galaxies (Q-LERGs). Through performing X-ray stacking, we determined the average X-ray luminosities, $L_{\rm{X, 2-10\,keV}}$ and average specific X-ray luminosities, $λ_{sL_{X}}$ (X-ray luminosity scaled by the stellar mass; a proxy for the accretion rate). We studied how these X-ray properties depend on radio luminosity, stellar mass, and redshift for each of the four AGN classes. We found that the LERGs, regardless of their star-formation activity, show significantly lower $L_{\rm{X, 2-10\,keV}}$ and $λ_{sL_{X}}$ than both HERGs and RQ-AGN across all redshifts. The average X-ray luminosities for the HERGs, RQ-AGN, and SF-LERGs typically increase with redshift, which may be associated with the increased cold gas fractions at earlier times, resulting in more enhanced black hole accretion. The average X-ray luminosities show weak-to-no correlation with radio luminosity at a given redshift, suggesting that the physical processes producing the X-ray and radio emission may not be coupled on spatial and/or temporal scales.
CommentsSubmitted to Monthly Notices of the Royal Astronomical Society (MNRAS). 10 pages, 5 figures. Updated version to correct the author list
