文章基本信息

标题：Modeling non-thermal emission from the jet-launching region of M 87 with adaptive mesh refinement
本地全文：下载
作者：Jordy Davelaar ; Hector Olivares ; Oliver Porth 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2019
卷号：632
页码：1-16
DOI：10.1051/0004-6361/201936150
语种：English
出版社：EDP Sciences
摘要：Context.The galaxy M 87 harbors a kiloparsec-scale relativistic jet, whose origin coincides with a compact source thought to be a supermassive black hole. Observational millimeter very long baseline interferometry campaigns are capable of resolving the jet-launching region at the scale of the event horizon. In order to provide a context for interpreting these observations, realistic general-relativistic magnetohydrodynamical (GRMHD) models of the accretion flow are constructed.Aims.Electrons in the jet are responsible for the observed synchrotron radiation, which is emitted in frequencies ranging from radio to near-infrared (NIR) and optical. The characteristics of the emitted radiation depend on the shape of the electrons’ energy-distribution function (eDF). The dependency on the eDF is omitted in the modeling of the first Event Horizon Telescope results. In this work, we aim to model the M 87 spectral-energy distribution from radio up to optical frequencies using a thermal-relativistic Maxwell–Jüttner distribution, as well as a relativisticκ-distribution function. The power-law index of the eDF is modeled based on sub-grid, particle-in-cell parametrizations for sub-relativistic reconnection.Methods.A GRMHD simulation in Cartesian–Kerr–Schild coordinates, using eight levels of adaptive mesh refinement (AMR), forms the basis of our model. To obtain spectra and images, the GRMHD data was post-processed with the ray-tracing codeRAPTOR, which is capable of ray tracing through GRMHD simulation data that is stored in multi-level AMR grids. The resulting spectra and images maps are compared with observations.Results.We obtain radio spectra in both the thermal-jet andκ-jet models consistent with radio observations. Additionally, theκ-jet models also recover the NIR and optical emission. The images show a more extended structure at 43 GHz and 86 GHz and more compact emission at 228 GHz. The models recover the observed source sizes and core shifts and obtain a jet power of ≈1043ergs s−1. In theκ-jet models, both the accretion rates and jet powers are approximately two times lower than the thermal-jet model. The frequency cut-off observed atν ≈ 1015Hz is recovered when the accelerator size is 106 − 108cm, this could potentially point to an upper limit for plasmoid sizes in the jet of M 87.
关键词：enblack hole physicsaccretionaccretion disksradiation mechanisms: non-thermalacceleration of particlesradiative transfer