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arXiv 1503.05090astro-ph.HE
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X1822-371中0.7 keV附近可能的回旋共振散射特征

A possible cyclotron resonance scattering feature near 0.7 keV in X1822-371

R. Iaria, T. Di Salvo, M. Matranga, C. G. Galiano, A. D'Aì, A. Riggio, L. Burderi, A. Sanna, C. Ferrigno, M. Del Santo, F. Pintore, N. R. Robba

摘要:

我们分析了XMM-牛顿,钱德拉,朱雀和INTEGRAL卫星对X1822-371的所有可用X射线观测。观察不是同时进行的。Suzaku和INTEGRAL宽带能量覆盖范围使我们能够很好地约束连续发射的光谱形状。我们使用的模型已经提出了这个源,由一个Comptonised组件吸收的星际物质和部分吸收的本地中性物质,我们添加了一个高斯吸收功能在$\sim 0.7$千电子伏。这一增加显著改善了拟合,并将残差在0.6和0.8 keV之间进行了调整。我们解释吸收的高斯特征作为一个回旋共振散射功能(CRSF)产生的中子星表面附近,并推导出在中子星表面的磁场强度,$(8.8 \pm 0.3) \times 10^{10}$ G为半径为10公里。我们推导出EPIC-pn数据中的脉冲周期为0.5928850(6)s,并使用所有可用的脉冲周期测量值估计X1822-371的自旋周期导数为$(-2.55 \pm 0.03) \times 10^{-12}$ s/s。假设X 1822 - 371的内禀光度处于爱丁顿极限,利用源的自旋周期和自旋周期导数值,我们约束了中子星和伴星的质量。我们发现中子星和伴星的质量分别为$1.69 \pm 0.13$ M $_{\odot}$和$0.46 \pm 0.02$ M $_{\odot}$,中子星半径为10 km。在自洽的情况下,X1822-371是自旋和在爱丁顿极限吸积,我们估计的磁场的中子星半径为10 km的中子星是$(8.8 \pm 0.3) \times 10^{10}$ G。如果我们的解释是正确的,高斯吸收功能附近的0.7 keV是第一次检测到CRSF低于1 keV的LMXB。(节略)

英文摘要:

We analyse all available X-ray observations of X1822-371 made with XMM-Newton, Chandra, Suzaku and INTEGRAL satellites. The observations were not simultaneous. The Suzaku and INTEGRAL broad band energy coverage allows us to constrain the spectral shape of the continuum emission well. We use the model already proposed for this source, consisting of a Comptonised component absorbed by interstellar matter and partially absorbed by local neutral matter, and we added a Gaussian feature in absorption at $\sim 0.7$ keV. This addition significantly improves the fit and flattens the residuals between 0.6 and 0.8 keV. We interpret the Gaussian feature in absorption as a cyclotron resonant scattering feature (CRSF) produced close to the neutron star surface and derive the magnetic field strength at the surface of the neutron star, $(8.8 \pm 0.3) \times 10^{10}$ G for a radius of 10 km. We derive the pulse period in the EPIC-pn data to be 0.5928850(6) s and estimate that the spin period derivative of X1822-371 is $(-2.55 \pm 0.03) \times 10^{-12}$ s/s using all available pulse period measurements. Assuming that the intrinsic luminosity of X1822-371is at the Eddington limit and using the values of spin period and spin period derivative of the source, we constrain the neutron star and companion star masses. We find the neutron star and the companion star masses to be $1.69 \pm 0.13$ M$_{\odot}$ and $0.46 \pm 0.02$ M$_{\odot}$, respectively, for a neutron star radius of 10 km.In a self-consistent scenario in which X1822-371 is spinning-up and accretes at the Eddington limit, we estimate that the magnetic field of the neutron star is $(8.8 \pm 0.3) \times 10^{10}$ G for a neutron star radius of 10 km. If our interpretation is correct, the Gaussian absorption feature near 0.7 keV is the very first detection of a CRSF below 1 keV in a LMXB. (abridged)

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