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arXiv 2502.08239astro-ph.HEastro-ph.SR
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吸积毫秒脉冲星SRGA J144459.2-604207的盘反射与能谱学

Disk reflection and energetics from the accreting millisecond pulsar SRGA J144459.2-604207

Christian Malacaria, Alessandro Papitto, Sergio Campana, Alessandro Di Marco, Tiziana Di Salvo, Maria Cristina Baglio, Giulia Illiano, Riccardo La Placa, Ariann… 展开作者

Christian Malacaria, Alessandro Papitto, Sergio Campana, Alessandro Di Marco, Tiziana Di Salvo, Maria Cristina Baglio, Giulia Illiano, Riccardo La Placa, Arianna Miraval Zanon, Maura Pilia, Juri Poutanen, Tuomo Salmi, Andrea Sanna, Manoj Mandal

AI总结:

本文利用XMM和NuSTAR观测数据分析了吸积毫秒脉冲星SRGA J144459的持续发射与I型爆发,通过物理反射模型揭示了盘截断、相对论展宽铁线及超快外流特征,并探讨了爆发复发时间异常的物理机制。

摘要:

吸积毫秒脉冲星(AMSPs)是研究反射光谱及其特征的绝佳实验室,这些特征源自在中子星表面附近被快速旋转磁层截断的吸积盘。这些系统还表现出热核(I型)爆发,能够为吸积物理和燃料成分提供深刻见解。我们研究了在2024年2月最近发现该源的爆发期间观测到的AMSP SRGA J144459的光谱特性。我们旨在利用最近一次爆发期间进行的XMM + NuSTAR重叠观测,来表征持续发射的光谱形状并分析I型爆发的特性。我们对时间平均的持续(即非爆发)发射进行了光谱分析。为此,我们首先采用了一个半唯象连续谱模型,该模型由主导的热康普顿化加上两个热贡献组成。此外,还使用物理反射模型进行了单独的拟合。我们还采用黑体模型对I型爆发进行了时间分辨光谱分析。我们观测到展宽的铁发射线,从而表明存在相对论效应,这得到了考虑相对论模糊反射的物理模型的支持。由此得出的吸积盘延伸至6个引力半径处,倾角约为53度,且仅处于中等电离状态(logξ≃2.3)。我们观测到约9.7 keV处的吸收边,可解释为由超快(≃0.04c)外流引起蓝移的Fe XXVI边。我们对I型爆发的宽带观测未发现光球半径膨胀的证据。爆发复发时间表现出对计数率的依赖性,其斜率是这些系统中迄今为止观测到最陡的。我们还观测到观测到的与预期的爆发复发时间之间存在约3倍的差异,我们在燃料成分和高NS质量情景的框架下对此进行了讨论。

英文摘要:

Accreting millisecond pulsars (AMSPs) are excellent laboratories to study reflection spectra and their features from an accretion disk truncated by a rapidly rotating magnetosphere near the neutron star surface. These systems also exhibit thermonuclear (type-I) bursts that can provide insights on the accretion physics and fuel composition. We explore spectral properties of the AMSP SRGA J144459 observed during the outburst that recently led to its discovery in February 2024. We aim to characterize the spectral shape of the persistent emission and to analyze type-I bursts properties employing XMM + NuSTAR overlapping observations taken during the most recent outburst. We perform spectral analysis of the time-averaged persistent (i.e., non-bursting) emission. For this, we first employ a semi-phenomenological continuum model made of a dominant thermal Comptonization plus two thermal contributions. A separate fit has also been performed employing a physical reflection model. We also perform time-resolved spectral analysis of a type-I burst employing a blackbody model. We observe a broadened iron emission line, thus suggesting relativistic effects, supported by the physical model accounting for relativistically blurred reflection. The resulting accretion disk extends down to 6 gravitational radii, inclined at ~$53^{\circ}$, and only moderately ionized (log$ξ\simeq2.3$). We observe an absorption edge at ~9.7 keV that can be interpreted as an Fe XXVI edge blueshifted by an ultrafast ($\simeq0.04$c) outflow. Our broadband observations of type-I bursts do not find evidence of photospheric radius expansion. The burst recurrence time shows a dependence on the count rate with the steepest slope ever observed in these systems. We also observe a discrepancy of ~3 between the observed and expected burst recurrence time, which we discuss in the framework of fuel composition and high NS mass scenarios.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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