发表机构
Max Planck Institute for Astronomy; Department of Astronomy, Astrophysics and Space Engineering, Indian Institute of Technology Indore（马克斯·普朗克天文学研究所; 印度印多尔理工学院天文、天体物理与空间工程系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过三维相对论磁流体动力学模拟发现，团块状星际介质显著增强AGN喷流的质量夹带、激波形成和同步辐射亮度，对理解年轻喷流早期演化至关重要。
AI 中文摘要
来自活动星系核（AGN）的相对论性喷流预计会穿过不均匀的星际介质（ISM），但小尺度气体不均匀性在塑造其早期演化中的作用仍不确定。我们使用PLUTO代码进行三维特殊相对论磁流体动力学模拟来研究这个问题，跟踪一个洛伦兹因子为10的喷流在秒差距尺度介质中的传播。我们将均匀环境介质与两个团块环境介质模型进行比较，这两个模型受核区星际介质中致密气体的启发，其中云团占据的体积填充因子分别为$0.1\\%$和$1\\%$。我们从经过扩散激波加速的拉格朗日宏粒子计算合成同步辐射图和光谱。喷流-云团相互作用偏转流动，增强激波形成，并产生比均匀星际介质情况更不对称的茧状结构。总的来说，这导致显著更强的质量加载：夹带质量从均匀运行中的$0.43\\,M_{\odot}$增加到团块运行中的$5.3$和$8.8\\,M_{\odot}$。团块星际介质还改变了喷流茧内的湍流和物质混合。我们发现的动力学差异转化为更亮且更不规则的同步辐射。对于相同的注入喷流，具有团块介质的模型产生比均匀运行更强的频率积分同步辐射，其中SED的最大差异出现在从亚毫米到红外/光学波段。我们的结果表明，包含小尺度星际介质结构为年轻AGN喷流的早期动力学演化及其辐射特性提供了更完整的描述。
英文摘要
Relativistic jets from AGN are expected to propagate through an inhomogeneous ISM, but the role of small-scale gas inhomogeneities in shaping their early evolution remains uncertain. We investigate this problem using 3D special-relativistic magnetohydrodynamic simulations with PLUTO, following a jet with a Lorentz factor of 10 propagating through a pc-scale medium. We compare a homogeneous ambient medium with two clumpy ambient-medium models, motivated by dense gas in the nuclear ISM, in which clouds occupy volume filling factors of $0.1$ and $1$ per cent. We compute synthetic synchrotron maps and spectra from Lagrangian macro-particles that have been accelerated by diffusive shock acceleration. Jet-cloud interactions deflect the flow, enhance shock formation, and produce a more asymmetric cocoon than in the homogeneous ISM case. Altogether, this results in a substantially stronger mass loading: the entrained mass increases from $0.43$ M$_{\odot}$ in the homogeneous run to $5.3$ and $8.8$ M$_{\odot}$ in the clumpy runs. The clumpy ISM also modifies the turbulence and the material mixing within the jet cocoon. The dynamical differences we find translate into brighter and more irregular synchrotron emission. For the same injected jet, the models with a clumpy medium produce stronger frequency-integrated synchrotron emission than the homogeneous run, with the largest differences in the SED occurring from the sub-mm to the infrared/optical bands. Our results demonstrate that including a small-scale ISM structure provides a more complete description of the early dynamical evolution of young AGN jets and their radiative properties.
Comments19 pages, 13 figures, accepted for publication in MNRAS
