论文标题
积聚驱动的毫秒脉冲星IGR J17591-2342的高能特征在其2018年爆发期间
High-energy characteristics of the accretion-powered millisecond pulsar IGR J17591-2342 during its 2018 outburst
论文作者
论文摘要
IGR J17591-2342 is a recently INTEGRAL discovered accreting millisecond X-ray pulsar that went into outburst around July 21, 2018. To better understand the physics acting in these systems during the outburst episode we performed detailed temporal-, timing- and spectral analyses across the 0.3-300 keV band using data from NICER, XMM-Newton, NuSTAR and INTEGRAL.硬X射线20-60 KEV爆发轮廓由四个耀斑组成。在最后耀斑的最大值期间，我们发现了I-I型热核爆发在整体JEM-X数据中。我们得出了7.6 +/- 0.7 kpc的距离，采用Eddington Luminiuntosiment Limited Photompheric Radius膨胀爆发发射并假设各向异性发射。在使用所有更好的1-10 KEV监视数据的定时分析中，我们观察到从旋转期开始的相当复杂的行为，然后是频率下降，恒定频率的发作以及以不规则行为结束，直到爆发结束。脉冲排放的1-50 keV阶段分布使用积分ISGRI数据检测到高达$ \ sim $ 120 keV，被分解为三个傅立叶谐波，表明，基本的脉冲分数从〜10％增加到〜10％增加到〜17％，从〜1.5 kev 〜1.5 kev降至〜4 kev，而硬质光的脉冲量则比较早的光子<10 ke for ofergies kev kev kev kev。在0.3-150 keV频段中，IGR J17591-2342的总发射光谱可以用吸收的COMPPS模型作为最佳拟合参数的圆柱密度n_h =（2.09 +/- 0.05）x 10^{22}} {22}}/cm2，黑型播种温度0.64+0.64 0.64+0.64+0.64 kt_e = 38.8 +/- 1.2 keV和汤姆森光学深度tau_t = 1.59 +/- 0.04。拟合归一化导致排放面积半径为11.3 +/- 0.5 km，采用7.6 kpc的距离。最后，在积聚物理和X射线热核突发理论的框架内讨论了结果。
IGR J17591-2342 is a recently INTEGRAL discovered accreting millisecond X-ray pulsar that went into outburst around July 21, 2018. To better understand the physics acting in these systems during the outburst episode we performed detailed temporal-, timing- and spectral analyses across the 0.3-300 keV band using data from NICER, XMM-Newton, NuSTAR and INTEGRAL. The hard X-ray 20-60 keV outburst profile is composed of four flares. During the maximum of the last flare we discovered a type-I thermonuclear burst in INTEGRAL JEM-X data. We derived a distance of 7.6+/-0.7 kpc, adopting Eddington luminosity limited photospheric radius expansion burst emission and assuming anisotropic emission. In the timing analysis using all NICER 1-10 keV monitoring data we observed a rather complex behaviour starting with a spin-up period, followed by a frequency drop, a episode of constant frequency and concluding with irregular behaviour till the end of the outburst. The 1-50 keV phase distributions of the pulsed emission, detected up to $\sim$ 120 keV using INTEGRAL ISGRI data, was decomposed in three Fourier harmonics showing that the pulsed fraction of the fundamental increases from ~10% to ~17% going from ~1.5 to ~4 keV, while the harder photons arrive earlier than the soft photons for energies <10 keV. The total emission spectrum of IGR J17591-2342 across the 0.3-150 keV band could adequately be fitted in terms of an absorbed compPS model yielding as best fit parameters a column density of N_H=(2.09+/-0.05) x 10^{22} /cm2, a blackbody seed photon temperature kT_bb,seed of 0.64+/- 0.02 keV, electron temperature kT_e=38.8+/-1.2 keV and Thomson optical depth Tau_T=1.59+/-0.04. The fit normalisation results in an emission area radius of 11.3+/-0.5 km adopting a distance of 7.6 kpc. Finally, the results are discussed within the framework of accretion physics- and X-ray thermonuclear burst theory.
