A new X-ray nova MAXI J1910-057 (= Swift J1910.2-0546) and mass accretion inflow
A new X-ray nova MAXI J1910-057 (= Swift J1910.2-0546) and mass accretion inflow
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新的 X 射线新星 MAXI J1910-057 (= Swift J1910.2-0546) 和质量吸积流入
DOI：
10.1093/pasj/psu060
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发表时间：
2014
影响因子：
2.3
通讯作者：
Masaru Matsuoka and Takuya Onodera
中科院分区：
文献类型：
--
作者：
Satoshi Nakahira;Hitoshi Negoro;Megumi Shidatsu;Yoshihiro Ueda;Tatehiro Mihara;Mutsumi Sugizaki;Masaru Matsuoka and Takuya Onodera
我们报告了 MAXI 和 Swift 对新发现的 X 射线新星 MAXI J1910−057 (= Swift J1910.2−0546) 的长期监测。 2012 年 5 月 31 日，MAXI 气体狭缝相机 (GSC) 和快速爆发警报望远镜 (BAT) 几乎同时首次检测到新的 X 射线瞬变。我们通过重复的 MAXI 扫描和 Swift 指向观测，分析了爆发爆发后 270 天的 X 射线和紫外线数据。获得的初始 90d 的 X 射线光曲线大致由快速上升和指数衰减曲线表示。然而，它在发病后约 110 天重新变亮，并最终在 240 天后降至 GSC 和 BAT 检测限以下。所有 X 射线能谱都与由多色盘黑体及其 Comptonized 硬尾组成的模型很好地拟合。在软状态期间，最佳拟合模型的内盘半径几乎恒定。如果半径代表非旋转黑洞最里面的稳定圆形轨道，并且软到硬的转变发生在爱丁顿光度的 1%–4% 处，则致密天体的质量估计为 > 2.9M⊙，距离为 > 1.70 kpc。内盘半径在硬/硬中间状态下变得更大。这表明吸积盘将被截断。我们检测到从 X 射线数据推断出的盘黑体分量上有过量的 UV 通量，这可以建模为由内盘照射的再处理发射。我们还发现，UV 光曲线主要追踪 X 射线曲线，但在 UV 和 X 射线波段均观察到短暂的下降事件，且 X 射线时滞为 3.5 d。这可以解释为吸积物质从外部 UV 区域径向流入内部 X 射线区域。
We report on long-term monitoring of a newly discovered X-ray nova, MAXI J1910−057 (= Swift J1910.2−0546) by MAXI and Swift. The new X-ray transient was first detected on 2012 May 31 by the MAXI Gas Slit Camera (GSC) and the Swift Burst Alert Telescope (BAT) almost simultaneously. We analyzed X-ray and UV data for 270 d following the outburst onset taken by repeated MAXI scans and Swift pointing observations. The obtained X-ray light curve for the inital 90 d is roughly represented by a fast-rise and exponential-decay profile. However, it re-brightened at ∼ 110 d after the onset and finally went down below both GSC and BAT detection limits after 240 d. All the X-ray energy spectra are fitted well with a model consisting of a multi-color-disk blackbody and its Comptonized hard tail. During the soft-state periods, the inner-disk radius of the best-fit model was almost constant. If the radius represents the innermost stable circular orbit of a non-spinning black hole and the soft-to-hard transitions occur at 1%–4% of the Eddington luminosity, the mass of the compact object is estimated to be > 2.9M⊙and the distance to be > 1.70 kpc. The inner-disk radius became larger in the hard/hard-intermediate state. This suggests that the accretion disk would be truncated. We detected an excess of the UV flux over the disk blackbody component extrapolated from the X-ray data, which can be modeled as reprocessed emission irradiated by the inner disk. We also found that the UV light curve mostly traced the X-ray curve, but a short dipping event was observed in both the UV and the X-ray bands with a 3.5 d X-ray time lag. This can be interpreted as the radial inflow of accreting matter from the outer UV region to the inner X-ray region.