Title: Bright end of the luminosity function of high-mass X-ray binaries: contributions of hard, soft and supersoft sources Show Chinese title

Title: 高质量X射线双星光度函数的明亮端：硬、软和超软源的贡献

Abstract: Using a spectral analysis of bright Chandra X-ray sources located in 27 nearby galaxies and maps of star-formation rate (SFR) and ISM surface densities for these galaxies, we constructed the intrinsic X-ray luminosity function (XLF) of luminous high-mass X-ray binaries (HMXBs), taking into account absorption effects and the diversity of HMXB spectra. The XLF per unit SFR can be described by a power law dN/d log L=2.0(L/10^39 erg/s)^(-0.6) (M_Sun/yr)^(-1) from L=10^38 to 10^40.5 erg/s, where L is the unabsorbed luminosity at 0.25-8 keV. The intrinsic number of luminous HMXBs per unit SFR is a factor of ~2.3 larger than the observed number reported before. The intrinsic XLF is composed of hard, soft and supersoft sources (defined here as those with the 0.25-2 keV to 0.25-8 keV flux ratio of <0.6, 0.6-0.95 and >0.95, respectively) in ~2:1:1 proportion. We also constructed the intrinsic HMXB XLF in the soft X-ray band (0.25-2 keV). Here, the numbers of hard, soft and supersoft sources prove to be nearly equal. The cumulative present-day 0.25-2 keV emissivity of HMXBs with luminosities between 10^38 and 10^40.5 erg/s is ~5 10^39 erg/s (M_Sun/yr)^(-1), which may be relevant for studying the X-ray preheating of the early Universe. Show Chinese abstract

Abstract: 通过分析27个附近星系中明亮钱德拉X射线源的光谱，以及这些星系的恒星形成率（SFR）和星际介质表面密度图，我们构建了高质量X射线双星（HMXBs）的固有X射线光度函数（XLF），考虑了吸收效应和HMXB光谱的多样性。 每单位SFR的XLF可以用幂律dN/d log L=2.0(L/10^39 erg/s)^(-0.6) (M_Sun/yr)^(-1) 来描述，范围为L=10^38到10^40.5 erg/s，其中L是0.25-8 keV未被吸收的光度。 每单位SFR的明亮HMXB的固有数量比之前报告的观测数量大约2.3倍。 固有的XLF由硬、软和超软源（此处定义为0.25-2 keV与0.25-8 keV通量比小于0.6、0.6-0.95和大于0.95的源）组成，比例约为2:1:1。 我们还构建了软X射线波段（0.25-2 keV）内HMXB的固有XLF。 在此波段，硬、软和超软源的数量几乎相等。 当前HMXB在10^38到10^40.5 erg/s光度范围内的0.25-2 keV累积发射率约为5×10^39 erg/s (M_Sun/yr)^(-1)，这可能与研究早期宇宙的X射线预加热有关。