论文标题
NGC 1672中ULX的光学对应物
Optical Counterparts of ULXs in NGC 1672
论文作者
论文摘要
In this work, we deploy archival data from {\it HST}, {\it Chandra}, {\it XMM-Newton}, and {\it Swift-XRT}, to probe the nature of 9 candidate ULXs in NGC 1672. Specifically, our study focuses on using the precise source positions obtained via improved astrometry based on {\it Chandra} and {\ it HST}观察值以搜索并确定这些ULX的潜在光学对应物。针对两个ULX候选物，即X2和X6确定了独特的光学对应物；对于三个候选物，即X1，X5和X7，我们在相应的误差半径内发现了两个潜在的对应物。未发现其余四个来源的光学对应物。 X2的频谱能分布安装在黑体光谱中，温度为$ \ sim $ 10 $^{4} $ K，并且源的光谱类别被确定为超级捐赠者的b7 $ - $ a3。我们使用颜色级图（CMD）来研究对应物的年龄。在所有研究的来源中，X9表现出最大的可变性，在2004年至2019年的时间段内，X射线通量在$ \ sim $ 50上的变化，并且在硬度强度图中也可以追踪部分Q曲线样特征，从而在可能的光谱过渡时提示。
In this work, we deploy archival data from {\it HST}, {\it Chandra}, {\it XMM-Newton}, and {\it Swift-XRT}, to probe the nature of 9 candidate ULXs in NGC 1672. Specifically, our study focuses on using the precise source positions obtained via improved astrometry based on {\it Chandra} and {\it HST} observations to search for and identify potential optical counterparts for these ULXs. Unique optical counterparts are identified for two of the ULX candidates i.e., X2 and X6; for three of the candidates i.e., X1, X5 and X7, we found two potential counterparts for each source within the respective error radii. No optical counterparts were found for the remaining four sources. The spectral energy distribution of X2 is fitted to a blackbody spectrum with a temperature of $\sim$ 10$^{4}$K and the spectral class of the source is determined to be B7$-$A3, a supergiant donor star. We used colour magnitude diagrams (CMDs) to investigate ages of the counterparts. Of all the sources studied, X9 exhibits the most variability whereby the X-ray flux varies by a factor of $\sim$ 50 over a time period spanning 2004 to 2019, and also traces a partial q-curve-like feature in the hardness-intensity diagram, hinting at possible spectral transitions.
