XMM-牛顿卫星和雨燕卫星揭示了 NGC 4945 中的另一个 X 射线瞬变源，XMM J130514.64-493311.27
XMM-Newton and Swift Unveil Another X-Ray Transient in NGC 4945, XMM J130514.64-493311.27
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中文总结 AI 辅助
研究利用 XMM-牛顿卫星和雨燕卫星在 NGC 4945 中发现 X 射线瞬变源 XMM J130514.64-493311.27，分析其特性并通过多种波段观测寻找对应体，最终提出该源是处于活跃阶段的 X 射线双星。
中文摘要 AI 辅助
NGC 4945 在其核心区域拥有一个康普顿厚、低光度的活动星系核和一个核星暴，此前一直是对活动星系核发射结构、核星暴特性和超亮 X 射线（ULX）源群体进行许多 X 射线研究的对象。在 NGC 4945 最新且最深的 XMM-牛顿观测中，报告了一个 X 射线瞬变源 XMM J130514.64-493311.27。该源位于核以南约 5.5 角分处，之前的 XMM-牛顿或钱德拉成像均未检测到，但雨燕-XRT 在 2008 年、2019 年和 2022 年检测到了它，2022 年的检测与新的 XMM-牛顿成像大致吻合。该源较软，Γ约为 3，光谱分析表明其最佳特征为多色盘+幂律模型或多色盘+热等离子体模型，0.3-10keV X 射线光度约为 2.2-2.3×10³⁸。在光学、近红外、紫外或射电波段未发现对应体，但在 NEOWISE 中红外光变曲线中识别出一个候选对应体。提出这个 X 射线源是 NGC 4945 中处于最近活跃阶段的一个 X 射线双星。
英文摘要
NGC 4945 hosts a Compton-thick, low luminosity AGN and a nuclear starburst in its core and has been the subject of many previous X-ray investigations of the AGN emission structure, nuclear starburst properties, and ultraluminous X-ray (ULX) source populations. Indeed, NGC 4945 has proven to be a rich system for ULX and X-ray transients, with at least four X-ray transients being reported over the last 15 years. Here we report the detection of an X-ray transient source, XMM J130514.64-493311.27, in NGC 4945 in the latest and deepest XMM-Newton observation of NGC 4945 to-date. The source lies $\sim5.5'$ south of the nucleus and was not detected in any previous XMM-Newton or Chandra imaging, but the source was detected by Swift-XRT in 2008, 2019, and in 2022, the latter of which coincides roughly with our new XMM-Newton imaging; we are therefore tracing the most recent outburst of this object with XMM-Newton. The source is soft with $Γ\approx3$, and our spectroscopic analysis suggests the source is best characterized by a multicolor disk + power law model or, alternatively, a multicolor disk + thermal plasma model, with a 0.3-10 keV X-ray luminosity of $\sim2.2-2.3\times10^{38}$. We find no evidence for a counterpart in the optical, near-infrared, ultraviolet, or in the radio, but we identify a candidate counterpart in NEOWISE mid-IR light curves. We propose that this X-ray source is an X-ray binary within NGC 4945 caught during its most recent active phase.
