论文标题
49年沉默后的4U〜1730--22的返回：nicer和Insight-HXMT观察到的2021/2022爆发的光谱特性以及由螺旋桨效应引起的软对状态过渡
Return of 4U~1730--22 after 49 years silence: the spectral properties of the 2021/2022 outbursts observed by NICER and Insight-HXMT and the soft-to-hard state transition caused by the propeller effect
论文作者
论文摘要
在静止49年后，4U〜1730--22变得活跃，并在2021年\＆2022年爆发了两次爆发，Nicer观察到了爆发的爆发和尾巴，这使我们有一个无与伦比的机会来研究国家过渡及其潜在机制。在这项工作中，我们同时将NS表面和积聚磁盘发射作为组合物的种子光子，并在1 \％-15 \％$ L _ {\ rm EDD} $的降压亮度范围内得出光谱演化。在高/软状态下，被推断的内磁盘半径和NS半径良好，这意味着吸积盘接近NS表面。对于衰变阶段，我们报告了一天之内的吸积盘排放的急剧变化，即柔软的过渡，这可能是由于螺旋桨效应和相应的中子星形表面磁场为1.8---2.2 $ \ times10^{8} $G。此外4U〜1608--52。在难以柔软的状态过渡中，螺旋桨效应的不存在意味着磁层积聚与磁盘积聚之间的过渡不是状态过渡的唯一原因。
After in quiescence for 49 years, 4U~1730--22 became active and had two outbursts in 2021 \& 2022, the onset and tail of the outbursts were observed by NICER, which give us a peerless opportunity to study the state transition and its underlying mechanism. In this work, we take both the NS surface and accretion disk emission as the seed photons of the Comptonization and derive their spectral evolution in a bolometric luminosity range of 1\%--15\%$L_{\rm Edd}$. In the high/soft state, the inferred inner disk radius and the NS radius are consistent well, which implies that the accretion disk is close to the NS surface. For the decay stage, we report a steep change of the accretion disk emission within one day, i.e., the soft-to-hard transition, which could be due to the propeller effect and the corresponding neutron star surface magnetic field is 1.8--2.2$\times10^{8}$ G. Moreover, the inner disk radius is truncated at the corotation radius, which is similar to the propeller effect detected from 4U~1608--52. The absence of the propeller effect in the hard-to-soft state transition implies that the transition between the magnetospheric accretion and the disk accretion is not the sole cause of the state transitions.
