Blazar jets launched with similar energy per baryon, independently of their power
Blazar jets launched with similar energy per baryon, independently of their power
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DOI：
10.1093/mnras/staa3925
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发表时间：
2021-01
影响因子：
4.8
通讯作者：
J. M. Rueda-Becerril;A. Harrison;D. Giannios
中科院分区：
文献类型：
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作者：
J. M. Rueda-Becerril;A. Harrison;D. Giannios
最活跃的星系核(AGN)是射电活跃的星系核，其相对论喷流在我们的视线附近传播。这些天体首先根据它们的发射线特征被分为平谱射电类星体(FSRQs)和BLLac天体(BLLac)。最近，观测揭示了这些天体之间的一种趋势，即所谓的\emph{blazar序列}，以及观测到的功率和同步加速器峰频率之间的反相关。在目前的工作中，我们提出了一个相当简单的想法，可以解释整个blazar群体：所有的喷气式飞机发射时，每个重子的能量相似，与它们的功率无关。在FSRQ的情况下，最强大的喷流设法加速到无线电中观察到的高体积洛伦兹因子。因此，它们在发射区具有相当温和的磁化强度，导致磁重联注入陡峭的粒子能量分布，从而在γ射线中产生陡峭的发射谱。对于较弱的喷流，即BLLac，则相反；即，喷流不能达到很高的体积洛伦兹因子，导致更多的磁能可用于非热粒子加速，并在频率$gtrsim$GeV处有较强的发射光谱。在这个场景中，我们用我们的模拟恢复了blazar的所有可观察到的性质，包括具有轻微重子加载的模型的\emph{blazar序列}($50\less sim\u\less sim 80$)。因此，这种对blazar群体的解释严格限制了blazar喷流的每重子能量，而不考虑它们的吸积率。
The most extreme active galactic nuclei (AGN) are the radio active ones whose relativistic jet propagates close to our line of sight. These objects were first classified according to their emission line features into flat-spectrum radio quasars (FSRQs) and BL Lacertae objects (BL Lacs). More recently, observations revealed a trend between these objects known as the \emph{blazar sequence}, along with an anti-correlation between the observed power and the frequency of the synchrotron peak. In the present work, we propose a fairly simple idea that could account for the whole blazar population: all jets are launched with similar energy per baryon, independently of their power. In the case of FSRQs, the most powerful jets, manage to accelerate to high bulk Lorentz factors, as observed in the radio. As a result, they have a rather modest magnetization in the emission region, resulting in magnetic reconnection injecting a steep particle energy distribution and, consequently, steep emission spectra in the $\gamma$-rays. For the weaker jets, namely BL Lacs, the opposite holds true; i.e., the jet does not achieve a very high bulk Lorentz factor, leading to more magnetic energy available for non-thermal particle acceleration, and harder emission spectra at frequencies $\gtrsim$ GeV. In this scenario, we recover all observable properties of blazars with our simulations, including the \emph{blazar sequence} for models with mild baryon loading ($50 \lesssim \mu \lesssim 80$). This interpretation of the blazar population, therefore, tightly constrains the energy per baryon of blazar jets regardless of their accretion rate.