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arXiv 1703.03354astro-ph.HE
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发光高质量X射线双星的本征集体X射线谱

The intrinsic collective X-ray spectrum of luminous high-mass X-ray binaries

Sergey Sazonov, Ildar Khabibullin

摘要:

使用200个发光的样本(L_unabs>10^38 erg/s,其中L_unabs是0.25-8 keV的未吸收光度)的高质量X射线双星(HMXB)候选者,我们构造了本地宇宙中HMXB的集体X射线谱,校正了与HMXB光谱和星际介质中X射线吸收的内在多样性相关的观测偏差。该光谱与光子指数γ =2.1+/-0.1的幂律很好地拟合,并且由L_unabs>10^39 erg/s的超铝X射线源主导。硬源(0.25-2 keV与0.25-8 keV通量比<0.6的源)在~2 keV以上占主导地位,而软源和超软源(通量比分别为0.6-0.95和>0.95)在较低能量下占主导地位。导出的光谱可能代表了本机宇宙中近和超临界吸积恒星质量黑洞和中子星的角积分X射线发射。它为超临界吸积模型提供了一个重要的约束条件,并可用作计算第一代X射线双星对宇宙的X射线预热的参考谱。

英文摘要:

Using a sample of two hundred luminous (L_unabs>10^38 erg/s, where L_unabs is the unabsorbed 0.25-8 keV luminosity) high-mass X-ray binary (HMXB) candidates found with Chandra in 27 nearby galaxies, we have constructed the collective X-ray spectrum of HMXBs in the local Universe per unit star formation rate, corrected for observational biases associated with intrinsic diversity of HMXB spectra and X-ray absorption in the interstellar medium. This spectrum is well fit by a power law with a photon index Gamma=2.1+/-0.1 and is dominated by ultraluminous X-ray sources with L_unabs>10^39 erg/s. Hard sources (those with the 0.25-2 keV to 0.25-8 keV flux ratio of <0.6) dominate above ~2 keV, while soft and supersoft sources (with the flux ratios of 0.6-0.95 and >0.95, respectively) at lower energies. The derived spectrum probably represents the angle-integrated X-ray emission of the near- and super-critically accreting stellar mass black holes and neutron stars in the local Universe. It provides an important constraint on supercritical accretion models and can be used as a reference spectrum for calculations of the X-ray preheating of the Universe by the first generations of X-ray binaries.

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