论文标题
紧凑型喷气机占主导地位的低亮度活性银核中的连续发射
Compact jets dominate the continuum emission in low-luminosity active galactic nuclei
论文作者
论文摘要
在低亮度活性银河核（LLAGN）中，积聚盘的消失留下了微弱的光学核连续体，其性质在很大程度上进行了争论，这主要是由于IR到UV范围内的严重观察局限性。我们将多波长的亚弧形分辨率观测（能够分离真正的核连续体）与中IR中的nebular线相结合，以间接探测极端紫外线连续体的形状。我们发现，8个最接近的原型LLAGN与纯紧凑型喷气发射（自吸收同步加速器以及相关的自compton组件）兼容，频率超过十个数量级。与典型的射电星系相比，llagn Continua显示了两个特殊性：$ i）$在IR到光学/UV范围内非常陡峭的光谱斜率（$ -3.7 <α_0<-1.3 $; $ f_6 $; $f_ν\ propto c propto和$ ii）$一个很高的周转频率（$ 0.2-30 \，\ rm {thz} $; $ 1.3 \，\ rm {mm} -10 \，\ rm {μm{μm} $）。如果同步加速器连续体主要由射流底座或电动机的热质颗粒支配，则可以解释这些属性，而温度相当高，而只有一小部分能量（$ \ sim 20 \％$）将沿高耐加速粒子的高又经式施分布。另一方面，LLAGN中的Nebular气体激发与来自Compton Inverse Compton辐射（$α_ {\ rm X} \ SIM -0.7 $）的光电率一致，这将统治$ \ sim 3000 $Å的核连续性缩短。我们的结果表明，LLAGN连续体可以通过未开发的喷气机在所有波长中占主导地位，并由热颗粒分布提供动力，类似于在静态黑孔X射线二进制文件的紧凑型射流中观察到的行为。这在星系进化的背景下具有重要意义，因为LLAGN可能代表了星系中动力学反馈的主要但低估的来源。
The disappearance of the accretion disc in low-luminosity active galactic nuclei (LLAGN) leaves behind a faint optical nuclear continuum whose nature has been largely debated, mainly due to serious observational limitations in the IR to UV range. We combine multi-wavelength sub-arcsecond resolution observations -- able to isolate the genuine nuclear continuum -- with nebular lines in the mid-IR, to indirectly probe the shape of the extreme UV continuum. We found that 8 of the nearest prototype LLAGN are compatible with pure compact jet emission (self-absorbed synchrotron plus the associated self-Compton component) over more than ten orders of magnitude in frequency. When compared with typical radio galaxies, the LLAGN continua show two peculiarities: $i)$ a very steep spectral slope in the IR-to-optical/UV range ($-3.7 < α_0 < -1.3$; $F_ν\propto ν^{α_0}$); and $ii)$ a very high turnover frequency ($0.2-30\, \rm{THz}$; $1.3\,\rm{mm}-10\,\rm{μm}$). These attributes can be explained if the synchrotron continuum is mainly dominated by thermalised particles at the jet base or corona with considerably high temperatures, whereas only a small fraction of the energy ($\sim 20\%$) would be distributed along the high-energy power-law tail of accelerated particles. On the other hand, the nebular gas excitation in LLAGN is in agreement with photo-ionisation from inverse Compton radiation ($α_{\rm x} \sim -0.7$), which would dominate the nuclear continuum shortwards of $\sim 3000$ Å. Our results suggest that the LLAGN continuum can be dominated at all wavelengths by undeveloped jets, powered by a thermalised particle distribution, similar to the behaviour observed in compact jets of quiescent black hole X-ray binaries. This has important implications in the context of galaxy evolution, since LLAGN may represent a major but underestimated source of kinetic feedback in galaxies.
