对准周期X射线爆发子GS 0836 - 429的新认识
New insights into the quasi-periodic X-ray burster GS 0836-429
摘要：
GS 0836 - 429是一个中子星X射线瞬变，显示I型X射线爆发。在2003年和2004年，它经历了两次X射线爆发。我们在这里提出的系统在这些爆发的爆发属性的分析。我们研究了2003 - 2004年爆发的演变，软X射线使用RXTE（2.5 - 12千电子伏; ASM），并在硬X射线与INTEGRAL（17 - 80千电子伏，IBIS/ISGRI）。使用INTEGRAL机载JEM-X监测器的数据，我们检测到61个I型X射线爆发，并确认该源显示了约2.3小时的准周期爆发重复时间。我们改进了燃料成分的表征，以及典型的爆发持续时间和注量的描述。我们估计$α$的平均值为$49\pm\,3$。这个值与观察到的突发配置文件一起表示由不稳定的氦点火触发的混合He/H失控的制度。此外，我们报告了四个系列的双突发，突发复发时间为$\leq\,20$分钟的检测。在双爆发中测量的重现时间太短，不允许足够的新鲜材料的积累，这是触发I型X射线爆发所必需的。这表明存在前一次爆炸留下的未燃烧物质，这些物质在几分钟的时间内被点燃。二次爆发的能量和时间尺度表明氢的比例较低，估计为主要爆发。在探测到I型X射线爆发期间，持续发射大致恒定。在观测$\dot{m}\sim\,8\,\%\,\dot{m}_{Edd}$的过程中，我们得到了一个平均吸积率。持续发射的光谱可以与非热分量相拟合，这表明当进行INTEGRAL观测时，源处于硬状态。
英文摘要：
GS 0836-429 is a neutron star X-ray transient that displays Type-I X-ray bursts. In 2003 and 2004 it experienced two outbursts in X-rays. We present here an analysis of the system bursting properties during these outbursts. We studied the evolution of the 2003-2004 outbursts in soft X-rays using RXTE (2.5-12 keV; ASM), and in hard X-rays with INTEGRAL (17-80 keV, IBIS/ISGRI). Using data from the JEM-X monitor onboard INTEGRAL we detected 61 Type-I X-ray bursts, and confirm that the source displayed a quasi-periodic burst recurrence time of about 2.3 hours. We improve the characterization of the fuel composition, as well as the description of the typical burst durations and fluences. We estimate the average value of $α$ to be $49\pm\,3$. This value together with the observed burst profiles indicate a regime of a mixed He/H runaway triggered by unstable helium ignition. In addition, we report the detection of four series of double bursts, with burst recurrence times of $\leq\,20$ minutes. The measured recurrence time in double bursts is too short to allow the accretion of enough fresh material, necessary to trigger a Type-I X-ray burst. This suggests the presence of left-over, unburned material from the preceding burst which gets ignited in a time scale of minutes. The energies and time scales of the secondary bursts suggest a lower fraction of hydrogen compared to that estimated for the primary bursts. The persistent emission was roughly constant during the period when the Type I X-ray bursts were detected. We derive an average accretion rate during our observations of $\dot{m}\sim\,8\,\%\,\dot{m}_{Edd}$. The spectrum of the persistent emission can be fit with a non-thermal component, indicative for the source to be in a hard state when the INTEGRAL observations were performed.
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