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arXiv 2305.09698astro-ph.HE
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辐射冷却对克尔黑洞周围磁化几何薄吸积盘的影响

Impact of radiative cooling on the magnetised geometrically thin accretion disk around Kerr black hole

Indu K. Dihingia, Yosuke Mizuno, Christian M. Fromm, Ziri Younsi

AI总结:

本文通过GRMHD模拟研究克尔黑洞磁化薄吸积盘,揭示吸积率与磁场强度共同调控盘风结构和日冕温度,从而影响X射线双星爆发中的光谱态转变。

摘要:

人们普遍认为,X射线双星(XRBs)爆发过程中的光谱态转变是由底层吸积盘不稳定性导致的质量吸积率上升所触发的。近期观测发现,盘风的特征很可能与不同的光谱态有关,但其理论依据仍十分模糊。为了理解盘风与吸积流动力学之间的相关性,我们对具有不同吸积率和磁场强度的轴对称薄吸积盘进行了广义相对论磁流体动力学(GRMHD)模拟。我们的模拟表明,动力学性质和温度性质同时依赖于吸积率和磁场强度。我们随后发现,这些性质会极大地影响光谱特性。我们计算了不同模拟模型的平均日冕温度,该温度与高能康普顿发射相关。我们的模拟模型揭示,平均日冕温度与吸积率呈反相关,而吸积率与磁场强度呈正相关。我们还发现,随着吸积率和磁场强度的增加,盘风的结构化成分(Blandford-Payne盘风)占据主导地位。相比之下,随着吸积率和磁场强度的降低,盘风的湍流成分($B_{\ m tor}$盘风)占据主导地位。我们的结果表明,只有在磁场贡献随时间变化的情况下(例如,MAXI J1820+070),才能理解X射线双星爆发期间的盘风现象。

英文摘要:

It is believed that the spectral state transitions of the outbursts in X-ray binaries (XRBs) are triggered by the rise of the mass accretion rate due to underlying disc instabilities. Recent observations found that characteristics of disc winds are probably connected with the different spectral states, but the theoretical underpinnings of it are highly ambiguous. To understand the correlation between disc winds and the dynamics of the accretion flow, we have performed General Relativistic Magneto-hydrodynamic (GRMHD) simulations of an axisymmetric thin accretion disc with different accretion rates and magnetic field strengths. Our simulations have shown that the dynamics and the temperature properties depend on both accretion rates and magnetic field strengths. We later found that these properties greatly influence spectral properties. We calculated the average coronal temperature for different simulation models, which is correlated with high-energy Compton emission. Our simulation models reveal that the average coronal temperature is anti-correlated with the accretion rates, which are correlated with the magnetic field strengths. We also found that the structured component of the disc winds (Blandford-Payne disc wind) predominates as the accretion rates and magnetic field strengths increase. In contrast, the turbulent component of the disc winds ($B_{\rm tor}$ disc wind) predominates as the accretion rates and magnetic field strengths decrease. Our results suggest that the disc winds during an outburst in XRBs can only be understood if the magnetic field contribution varies over time (e.g., MAXI J1820+070).

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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