论文标题
Maxi J1820+070与Nustar II。在难以柔软的状态过渡期间爆炸
MAXI J1820+070 with NuSTAR II. Flaring during the hard to soft state transition with a long soft lag
论文作者
论文摘要
我们继续对Maxi J1820+070（光学对应物Asassn-18ey）的最新发现爆发中的Nustar数据进行分析，重点关注观察结果，包括在难以软状态过渡期间的异常爆炸行为，这是爆发的短期爆发阶段，并且相当地观察到了较少的观察。两次通量中的两个高原通过持续约10 k的可变间隔隔开，该间隔显示浸入然后膨胀阶段。可变性最强（分数可变性高达$ f _ {\ rm var} \ sim10 \％$），并且随着圆盘排放的贡献变得更强大，可变性。磁通分辨的光谱表明，可变性主要是由于幂定律通量改变。我们还发现了幂定律发射背后的热滞后，在耀斑阶段为$ 20 _ { - 1.2}^{+1.6} $。浸入阶段的滞后具有不同的滞后频谱，这可能是由于波浪向外传递的波浪。时间解析的光谱拟合表明，在耀斑阶段的滞后可能是由于盘盘被破坏后重新填充以产生功率定律耀斑，这可能与在1天前大约发生的射流弹射后沉降的系统有关。这些现象的时间尺度意味着对于圆盘的内部区域，粘度参数低，$α\ sim10^{ - 3} $。
We continue the analysis of NuSTAR data from the recent discovery outburst of MAXI J1820+070 (optical counterpart ASASSN-18ey), focussing on an observation including unusual flaring behaviour during the hard to soft state transition, which is a short phase of outbursts and so comparatively rarely observed. Two plateaus in flux are separated by a variable interval lasting ~10 ks, which shows dipping then flaring stages. The variability is strongest (with fractional variability up to $F_{\rm Var}\sim10\%$) at high energies and reduces as the contribution from disc emission becomes stronger. Flux-resolved spectra show that the variability is primarily due to the power law flux changing. We also find a long soft lag of the thermal behind the power law emission, which is $20_{-1.2}^{+1.6}$ s during the flaring phase. The lag during the dipping stage has a different lag-energy spectrum, which may be due to a wave passing outwards through the disc. Time resolved spectral fitting suggests that the lag during the flaring stage may be due to the disc re-filling after being disrupted to produce the power law flare, perhaps related to the system settling after the jet ejection which occurred around 1 day before. The timescales of these phenomena imply a low viscosity parameter, $α\sim10^{-3}$, for the inner region of the disc.
