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arXiv 1603.07892astro-ph.HE
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GK每2015年由朱雀星覆盖的矮新星

GK Per 2015 dwarf nova covered by Suzaku

Takayuki Yuasa, Takayuki Hayashi, Manabu Ishida

摘要:

中间极区的GK Per在2015年3月至4月间爆发了一次矮新星爆发。朱雀X射线望远镜在其预定的为期四天的定点观测中偶然捕捉到了爆发的开始。在本文中,我们提出的时间和频谱分析结果的爆发,连同那些从档案数据的静态在2009年和2014年获得的。我们的时间分析证实了先前报道的X射线计数率的自旋调制与WD自旋周期PWD =351.4+/-0.5秒的爆发。在硬X射线波段(16-60 keV)也检测到了这种调制,对吸收的光谱建模表明,这种调制被一种稠密的吸收所遮蔽,其视线柱密度N_H>10^23 cm^-2。一个复杂的时间演化的自旋调制配置文件中看到的自旋最小相位从相位~0.25在第一个半观测到~0.65在第二个,和脉冲形状显着改变历元。Fe Ka带的光谱拟合显示荧光线等效宽度增加,从~80 eV(静止)增加到~140 eV(爆发)。类He和类H Fe K α的等效宽度在两种状态下都是恒定的,约为40 eV。在2-60 keV波段进行宽波段光谱拟合,得到亚太阳Fe丰度约为0.1 Zsun,采用等压冷却流模型时等离子体最高温度kT_max约为50-60 keV。基于在6-7倍的吸积速率下温度变化很小的情况,讨论了爆发早期的吸积几何。

英文摘要:

The intermediate polar GK Per exhibited a dwarf nova outburst in March-April 2015. Suzaku X-ray telescope serendipitously captured the onset of the outburst during its pre-scheduled pointing observation spanning four days. In this paper, we present temporal and spectral analysis results of this outburst, together with those from archival data of quiescent obtained in 2009 and 2014. Our temporal analysis confirmed previously reported spin modulation of X-ray count rates in outburst with a WD spin period of P_WD=351.4+/-0.5 s. The modulation is also detected in the hard X-ray band (16-60 keV), and spectral modeling of the absorption suggests obscuration by a dense absorption with a line-of-sight column density of N_H>10^23 cm^-2. A complex time evolution of spin modulation profiles is seen; the spin minimum phase shifts from phase ~0.25 in the first half of the observation to ~0.65 in the second one, and the pulse shape significantly changes epoch by epoch. Spectral fitting in the Fe Kalpha band revealed an increase of the fluorescent line equivalent width, from ~80 eV (quiescent) to ~140 eV (outburst). The equivalent widths of He-like and H-like Fe Kalpha are consistent with being constant at ~40 eV in the two states. Broad-band spectral fitting in the 2-60 keV band resulted in a sub-solar Fe abundance of ~0.1 Z_sun and the maximum plasma temperature kT_max~50-60 keV when the isobaric cooling flow model was applied. Based on the very small temperature change against a 6-7-times increased accretion rate, the accretion geometry in early outburst is discussed.

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