Nättilä Joonas
Department of Physics, University of Helsinki, P.O. Box 64, FI-00014, University of Helsinki, Finland.
Physics Department and Columbia Astrophysics Laboratory, Columbia University, 538 West 120th Street, New York, NY, 10027, USA.
Nat Commun. 2024 Aug 15;15(1):7026. doi: 10.1038/s41467-024-51257-1.
Stellar-mass black holes in x-ray binary systems are powered by mass transfer from a companion star. The accreted gas forms an accretion disk around the black hole and emits x-ray radiation in two distinct modes: hard and soft state. The origin of the states is unknown. We perform radiative plasma simulations of the electron-positron-photon corona around the inner accretion flow. Our simulations extend previous efforts by self-consistently including all the prevalent quantum electrodynamic processes. We demonstrate that when the plasma is turbulent, it naturally generates the observed hard-state emission. In addition, we show that when soft x-ray photons irradiate the system-mimicking radiation from an accretion disk-the turbulent plasma transitions into a new equilibrium state that generates the observed soft-state emission. Our findings demonstrate that turbulent motions of magnetized plasma can power black-hole accretion flow coronae and that quantum electrodynamic processes control the underlying state of the plasma.
X射线双星系统中的恒星质量黑洞由伴星的物质转移提供能量。吸积的气体在黑洞周围形成一个吸积盘，并以两种不同模式发射X射线辐射：硬态和软态。这两种状态的起源尚不清楚。我们对内吸积流周围的电子-正电子-光子冕进行了辐射等离子体模拟。我们的模拟通过自洽地纳入所有普遍的量子电动力学过程，扩展了先前的研究。我们证明，当等离子体呈湍流状态时，它自然会产生观测到的硬态辐射。此外，我们还表明，当软X射线光子照射该系统（模拟来自吸积盘的辐射）时，湍流等离子体会转变为一种新的平衡状态，从而产生观测到的软态辐射。我们的研究结果表明，磁化等离子体的湍流运动可以为黑洞吸积流冕提供能量，并且量子电动力学过程控制着等离子体的基本状态。
