费米 Blazars 的射电-伽马射线性质及高能辐射意义
Radio-Gamma-Ray Properties and High-Energy Implications for Fermi Blazars
浏览论文内容
中文总结 AI 辅助
本研究基于1687个费米Blazars样本，探究射电与伽马射线辐射关联，明确不同子类的相关性及磁场约束，揭示高能辐射机制。
中文摘要 AI 辅助
Blazars 是活动星系核（AGNs）的一个子类，其射电与伽马射线辐射为研究高能辐射过程提供了重要线索。本研究基于射电基础星表及最新的第四代费米 AGN 星表第三次数据释放，对 1687 个 Fermi Blazars 大样本开展射电与伽马射线辐射的关联研究。BL Lac 天体（BL Lacs）与平谱射电类星体（FSRQs）的射电和伽马射线流量均呈现明显相关性，表明两类天体均存在同步自康普顿（SSC）贡献。进一步对伽马射线与射电辐射的比值——伽马射线光度比（$G_{\rm r}$），与伽马射线光子指数（$\rm \bar{\rm \nu_{\rm peak}}$）开展研究，发现 $G_{\rm r}$ 与 $\rm \bar{\rm \nu_{\rm peak}}$ 呈反相关，该现象由能谱能量分布的偏移而非康普顿冷却效应导致。研究还发现，低同步峰 BL Lac 天体（LBLs）与 FSRQs 的 $G_{\rm r}$ 对 $\nu_{\rm peak}$ 呈正依赖，与 SSC 贡献的情形一致，不过 LBLs 和 FSRQs 中观测到的显著散射或可由额外的外康普顿贡献解释。与之相反，高同步峰 BL Lac 天体（HBLs）在 $\rm \nu_{\rm peak}/{\rm Hz} \rightleftharpoons15.5-16$ 区间达到 $G_{\rm r}$ 平台，可能标志着从汤姆逊区到克莱因- Nishina（KN）区的转变。在单区 SSC 框架下解释该特征，可对受 KN 抑制影响的 HBLs 磁场强度进行约束，其范围为 $-4.14 < \rm \bar{\rm \nu_{\rm peak}} < -1.69$（单位：G）。
英文摘要
Radio and $γ$-ray emissions in blazars, a subclass of active galactic nuclei (AGNs), provide important insight into their high-energy radiation processes. We studied the relation between radio and $γ$-ray emissions using a large sample of 1687 \textit{Fermi} blazars, based on the Radio Fundamental Catalogue and the latest Third Data Release of the Fourth \textit{Fermi} AGN Catalogue. A clear correlation between radio and $γ$-ray fluxes for both BL Lacertae objects (BL Lacs) and flat-spectrum radio quasars (FSRQs) suggests a synchrotron self-Compton (SSC) contribution to both subclasses. The ratio of $γ$-ray and radio emissions, $γ$-ray loudness ($G_{\rm r}$), is further examined with the $γ$-ray photon index ($Γ_γ$) and the synchrotron peak frequency ($ν_{\rm{peak}}$). An anti-correlation between $G_{\rm r}$ and $Γ_γ$ is explained by the shift of the spectral energy distribution rather than the Compton cooling effect. We found that $G_{\rm r}$ shows a positive dependence on $ν_{\rm{peak}}$ for low-synchrotron-peaked BL Lacs (LBLs) and FSRQs, in line with the SSC-contributed scenario, although additional external Compton contributions may account for the substantial scatter observed in LBLs and FSRQs. In contrast, high-synchrotron-peaked BL Lacs (HBLs) reach the plateau of $G_{\rm r}$ between $\log (ν_{\rm peak}/{\rm Hz}) \simeq15.5-16$, possibly indicating the transition from the Thomson to the Klein--Nishina (KN) regime. Interpreting this feature within a one-zone SSC framework could constrain the magnetic field strength of $-4.14 < \log (B/{\rm G}) < -1.69$ for those HBLs affected by the KN suppression.
