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arXiv 1207.2148astro-ph.HE
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X射线源1 RXS J180431 .1-273932作为磁激变变星的光学鉴别

Optical identification of X-ray source 1RXS J180431.1-273932 as a magnetic cataclysmic variable

N. Masetti, A. A. Nucita, P. Parisi

摘要:

X射线源1 RXS J180431.1-273932被认为是共生X射线双星(SyXB)系统的新成员,SyXB系统由一颗晚型巨星组成,它的物质被一个非常紧凑的物体(很可能是中子星)所吸收。在本文中,我们提出了一个光学运动的成像加上光谱学上选择的候选人对应的这个对象。我们还重新分析了可用的档案X射线数据收集与XMM牛顿。我们发现,最亮的光源内的90%的X射线位置误差圆光谱确定为一个磁激变变量(CV),最有可能的中间极性类型,通过检测突出的巴耳末,他我,他II,和鲍文混合排放。无论是光谱或统计的理由,我们丢弃的对应物的X射线源的其他光学对象在XMM牛顿误差圆。在X射线位置之外发现了一颗光谱型为M5 III的红巨星:我们认为后者是前/背景天体,同样排除了它是1 RXS J180431.1-273932的对应物。使用韧致辐射加黑体模型的源的X射线光谱的描述给出了这两个组件的温度分别为约40 keV和约0.1 keV。利用X射线谱分析得到的信息,我们估计该系统的距离约为450秒差距,0.2-10千电子伏的X射线光度约为1.7e ~(32)erg/s,并估计吸积中的白矮星(WD)的质量约为0.8太阳质量。我们还确认了这个源的X射线周期为494秒,我们解释为WD的自旋周期。总之,1 RXS J180431.1-273932被确定为磁性CV,其SyXB性质被排除在外。

英文摘要:

The X-ray source 1RXS J180431.1-273932 has been proposed as a new member of the symbiotic X-ray binary (SyXB) class of systems, which are composed of a late-type giant that loses matter to an extremely compact object, most likely a neutron star. In this paper, we present an optical campaign of imaging plus spectroscopy on selected candidate counterparts of this object. We also reanalyzed the available archival X-ray data collected with XMM-Newton. We find that the brightest optical source inside the 90% X-ray positional error circle is spectroscopically identified as a magnetic cataclysmic variable (CV), most likely of intermediate polar type, through the detection of prominent Balmer, He I, He II, and Bowen blend emissions. On either spectroscopic or statistical grounds, we discard as counterparts of the X-ray source the other optical objects in the XMM-Newton error circle. A red giant star of spectral type M5 III is found lying just outside the X-ray position: we consider this latter object as a fore-/background one and likewise rule it out as a counterpart of 1RXS J180431.1-273932. The description of the X-ray spectrum of the source using a bremsstrahlung plus black-body model gives temperatures of around 40 keV and around 0.1 keV for these two components, respectively. We estimate a distance of about 450 pc and a 0.2-10 keV X-ray luminosity of about 1.7e32 erg/s for this system and, using the information obtained from the X-ray spectral analysis, a mass of about 0.8 solar masses for the accreting white dwarf (WD). We also confirm an X-ray periodicity of 494 s for this source, which we interpret as the spin period of the WD. In summary, 1RXS J180431.1-273932 is identified as a magnetic CV and its SyXB nature is excluded.

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