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arXiv 1507.02411astro-ph.HE
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XMM-牛顿和日食极区CSS081231的光学观测:071126+440405

XMM-Newton and optical observations of the eclipsing polar CSS081231:071126+440405

H. Worpel, A. D. Schwope

摘要:

目的:我们的目标是研究日食极CSS 081231:071126+440405的时间和光谱行为,从红外到X射线制度。方法:我们在2012年和2013年两次获得了不同吸积状态下的相位分辨XMM-牛顿X射线观测。2013年,XMM-牛顿的X射线和紫外数据得到了光学光度和光谱观测的补充。结果:CSS 081231在高态下表现为两极吸积。两极的磁场为36和69 MG,表明非偶极场几何形状。低场主吸积极的X射线谱包括来自冷却吸积等离子体的几十keV的$kT_{plas}$的热的热分量和来自吸积区域的$kT_{\rm bb} \sim$ 50- 100 eV的低得多的发光的类黑体分量。高场极与质量贡献星相对,以低速吸积,等离子体温度约为4.keV。在这两种情况下,X射线日食的中点都比光学日食的中点早3.2秒。X射线亮相的中心显示了约20度的吸积率依赖的纵向运动。结论:CSS 081231是一个明亮的极性,在RASS调查中没有被检测到,因为它处于低吸积状态。即使在高状态下,它也缺乏以前认为在极性中普遍存在的突出的软成分。这种过量可能仍然存在于未观测到的极紫外线中。在XMM-牛顿时代发现的所有极性都缺乏突出的软成分。极地的固有光谱能量分布仍有待于未来的X射线调查,如eROSITA的特点。物质到达第二个极点的轨迹仍然不确定。

英文摘要:

Aims: We aim to study the temporal and spectral behaviour of the eclipsing polar CSS081231:071126+440405 from the infrared to the X-ray regime. Methods: We obtained phase-resolved XMM-Newton X-ray observations on two occasions in 2012 and 2013 in different states of accretion. In 2013 the XMM-Newton X-ray and UV data were complemented by optical photometric and spectroscopic observations. Results: CSS081231 displays two-pole accretion in the high state. The magnetic fields of the two poles are 36 and 69 MG, indicating a non-dipolar field geometry. The X-ray spectrum of the main accreting pole with the lower field comprises a hot thermal component from the cooling accretion plasma, $kT_{plas}$ of a few tens of keV, and a much less luminous blackbody-like component from the accretion area with $kT_{\rm bb} \sim$ 50-100\,eV. The high-field pole which was located opposite to the mass-donating star accretes at a low rate and has a plasma temperature of about 4\,keV. At both occasions the X-ray eclipse midpoint precedes the optical eclipse midpoint by 3.2 seconds. The center of the X-ray bright phase shows accretion-rate dependent longitudinal motion of ~20 degrees. Conclusions: CSS081231 is a bright polar that escaped detection in the RASS survey because it was in a low accretion state. Even in the high state it lacks the prominent soft component previously thought ubiquitous in polars. Such an excess may still be present in the unobserved extreme ultraviolet. All polars discovered in the XMM-Newton era lack the prominent soft component. The intrinsic spectral energy distribution of polars still awaits characterisation by future X-ray surveys such as eROSITA. The trajectory taken by material to reach the second pole is still uncertain.

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