首次eROSITA巡天中的极亮X射线源 I. 候选体表
Ultraluminous X-ray sources in the first eROSITA survey I. Candidate catalogs
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中文总结 AI 辅助
该研究基于首次eROSITA巡天数据，从HECATE星表的约10^5个星系中筛选出高置信度90个、低置信度260个ULX候选体，揭示了ULX的瞬变特性，为ULX研究提供了可靠候选样本。
中文摘要 AI 辅助
极亮X射线源（ULXs）是嵌入星系中的明亮非核X射线点源，其光度超过10^39 erg/s，这可能需要质量约为10^2 M⊙至10^4 M⊙的天体以亚爱丁顿吸积模式吸积，或恒星级黑洞、中子星以超过爱丁顿极限的超临界吸积模式吸积。我们通过在首次eROSITA全天巡天的天区内，对HECATE星表中约10^5个星系搜索X射线对应体来识别ULXs，同时排除核区以避免选到活动星系核（AGN）。我们表征了样本的完整性、未认证AGN的污染情况，并确定了源混淆的影响；该星表不受X射线选择偏差的影响。我们移除了超新星、恒星、AGN等已知污染物，并对所有候选体进行人工审核以进一步去除污染物。我们通过模拟及后续源探测推导了X射线选择函数和未认证AGN干扰体的占比。我们给出了两个ULX候选体样本：主样本包含90个具有高置信度X射线探测的源，其中53个为首次识别；该样本在约7Mpc的距离内是完整的，包含的未知背景AGN占比最多为29%，且基本不受源混淆影响。部分候选体即使在其他仪器已观测过其位置的情况下仍被新识别，而一些我们预期会识别的先前报道的候选体未出现在我们的样本中，这体现了ULXs的瞬变特性。基于置信度较低的探测列表，我们还提供了包含260个源的扩展星表，作为进一步识别ULX的潜在候选体，其中245个为首次识别。
英文摘要
Ultraluminous X-ray sources (ULXs) are luminous non-nuclear X-ray point sources embedded in galaxies. Their luminosities exceeding 10^39 erg/s potentially require sub-Eddington accretion by objects with masses from ~10^2$M_{\odot}$ to ~10^4$M_{\odot}$ or supercritical accretion beyond the Eddington limit by stellar mass black holes or neutron stars. We identified ULXs by searching for X-ray counterparts in the ~10^5 galaxies of the HECATE catalog in the footprint of the first eROSITA all-sky survey, while excluding nuclear regions to avoid the selection of active galactic nuclei (AGN). We characterized the completeness of the sample and its contamination by unidentified AGN and determined the influence of source confusion. The catalog is unaffected by X-ray selection biases. We removed known contaminants such as supernovae, stars, and AGN, and manually vetted all candidates to further remove contaminants. We derived the X-ray selection function and fraction of unidentified AGN interlopers using a simulation with subsequent source detection. We present two samples of ULX candidates. The main sample consists of 90 sources with highly confident X-ray detections, 53 of which are identified for the first time. This sample is complete to a distance of ~7Mpc, contains at most 29% of unknown background AGN, and is mostly unaffected by source confusion. Several candidates are newly identified even though their locations have been observed by other instruments before, and some previously reported candidates we expected to identify are absent from our sample, demonstrating the transient behavior of ULXs. Based on our list of less confident detections, we also provide an extended catalog of 260 sources identified as potential candidates for further ULX identifications. Of these, 245 are identified as potential candidates for the first time. (Abridged)
