AI 中文总结
本研究通过EHT与GRAVITY观测，结合MCMC分析约束ModMax黑洞的参数Q与v，揭示其对黑洞阴影及薄吸积盘辐射的影响，获得95%可信水平下的Q与v上限。
AI 中文摘要
本研究探讨ModMax黑洞周围薄吸积盘的光子传播与辐射特性，分析电荷Q（Q²=Qₑ²+Qₘ²，其中Qₑ为电荷、Qₘ为磁荷，Q为总双子荷）和非线性参数v的影响。我们确定了事件视界、光子球与阴影半径，发现增大Q会使这些半径减小，而增大v则会使这些半径趋近于史瓦西黑洞的对应值。结合EHT对M87*与Sgr A*的阴影测量结果，以及已有的质量与距离测量数据，我们开展马尔可夫链蒙特卡洛（MCMC）分析以约束ModMax参数，在95%可信水平下得到最强上限：Q<0.391，v<4.153。我们还研究了Novikov-Thorne薄吸积盘，并通过后向光线追踪生成模拟盘图像；观测通量随Q增大而升高，而v增大会使盘亮度略有下降。这些结果揭示了ModMax参数对黑洞阴影与薄盘辐射的影响，为Q和v提供了观测约束。
英文摘要
In this work, we study photon propagation and the radiative properties of a thin accretion disk around a ModMax black hole and examine the effects of the charge $Q$ (i.e. $Q^2 = Q^2_e +Q^2_m$ is the total dyonic charge, with $Q_e$ and $Q_m$ denoting the electric and magnetic charges, respectively) and the nonlinearity parameter $v$. We determine the event-horizon, photon-sphere, and shadow radii and find that increasing $Q$ decreases these radii, whereas increasing $v$ shifts them toward their Schwarzschild values. Using the EHT shadow measurements of M87$^\star$ and Sgr~A$^\star$, together with the available mass and distance measurements, we perform an MCMC analysis to constrain the ModMax parameters. The strongest upper limits are found to be $Q<0.391$ and $v<4.153$ at the 95\% credible level. We also investigate a Novikov-Thorne thin accretion disk and generate simulated disk images using backward ray tracing. The observed flux increases with $Q$, while increasing $v$ produces a slight decrease in the disk brightness. These results show how the ModMax parameters affect the black-hole shadow and thin-disk emission and provide observational constraints on $Q$ and $v$.
Comments12 pages, 6 captioned figures, 2 tables
