论文标题
通过线性和圆极化图像中的通量分离研究M87中的圆盘喷射结构
Investigating the Disk-Jet Structure in M87 through Flux Separation in the Linear and Circular Polarization Images
论文作者
论文摘要
为了测试一般相对论磁性水力学（GRMHD）模拟的不同电子温度（$ t _ {\ rm e} $），我们建议利用线性极化（LP）和圆极化（CP）图像。我们根据各种$ t _ {\ rm e} $参数的半磁性磁盘（MAD）GRMHD模型来计算极化图像，考虑到M87。我们在230 GHz的低$ t _ {\ rm e} $磁盘盒的图像中找到了LP-CP分离；也就是说，LP通量主要起源于射流的下游，而CP通量来自柜台射流，而总强度在射流底座处最大。 This can be understood as follows: although the LP flux is generated through synchrotron emission widely around the black hole, most of the LP flux from the jet base does not reach the observer, since it undergoes Faraday rotation ($\propto T_{\rm e}^{-2}$) when passing through the outer cold disk and is thus depolarized.因此，只有从下游（不通过冷致密的等离子体）的LP通量才能生存。同时，CP通量是由Faraday转换（$ \ propto t _ {\ rm e} $）中的LP通量生成的。因此，从反侧射流观察到更强的CP通量。此外，在较低的频率（例如86 GHz）下，LP-CP分离更加增强，但在43 GHz时相当较弱，因为后一种情况下的介质对于同步体的自我吸收而光学厚度厚，因此所有磁通都应来自Photosphere。对于质量积聚率较高和/或较大倾斜角的病例也是如此。
For testing different electron temperature ($T_{\rm e}$) prescriptions in general relativistic magnetohydrodynamics (GRMHD) simulations through observations, we propose to utilize linear polarization (LP) and circular polarization (CP) images. We calculate the polarization images based on a semi-Magnetically Arrested Disk (MAD) GRMHD model for various $T_{\rm e}$ parameters, bearing M87 in mind. We find an LP-CP separation in the images of the low-$T_{\rm e}$ disk cases at 230 GHz; namely, the LP flux mainly originates from downstream of the jet and the CP flux comes from the counter-side jet, while the total intensity is maximum at the jet base. This can be understood as follows: although the LP flux is generated through synchrotron emission widely around the black hole, most of the LP flux from the jet base does not reach the observer, since it undergoes Faraday rotation ($\propto T_{\rm e}^{-2}$) when passing through the outer cold disk and is thus depolarized. Hence, only the LP flux from the downstream (not passing the cold dense plasmas) can survive. Meanwhile, the CP flux is generated from the LP flux by Faraday conversion ($\propto T_{\rm e}$) in the inner hot region. Stronger CP flux is thus observed from the counter-side jet. Moreover, the LP-CP separation is more enhanced at a lower frequency such as 86 GHz but is rather weak at 43 GHz, since the media in the latter case is optically thick for synchrotron self-absorption so that all the fluxes should come from the photosphere. The same is true for cases with higher mass accretion rates and/or larger inclination angles.
