AI 中文总结
本研究通过JWST和HST观测确定EP250207b的宿主星系红移为z=3.2，发现其可能起源于坍缩星，而非最初认为的双中子星并合。
AI 中文摘要
我们呈现了詹姆斯·韦布空间望远镜（JWST）和哈勃空间望远镜（HST）对爱因斯坦探测器探测到的快速X射线暂现源（FXT）EP250207b天区的观测结果，以解决该FXT宿主星系及红移的歧义问题。EP250207b最初基于低概率空间关联被归为红移z=0.082的近邻星系，并被提出起源于双中子星并合。但我们报告在EP250207b位置探测到一个红移z=3.2的背景星系，假设该星系为实际宿主星系，事件的静止帧能量和时标会发生变化；此外，现有数据无法排除该红移下EP250207b关联超新星的可能性。我们使用Redback中实现的顶帽喷流模型对X射线、光学、近红外和射电光变曲线建模，发现其与轴上伽马暴余辉一致，能量和宿主星系性质无法区分坍缩星和并合驱动的事件。
英文摘要
We present James Webb Space Telescope (JWST) and Hubble Space Telescope (HST) observations of the field of the fast X-ray transient (FXT) detected by Einstein Probe, EP250207b, to resolve any ambiguity about the host galaxy and redshift of the FXT. EP250207b was originally associated with a nearby galaxy at z=0.082, based on its low chance alignment probability, and a binary neutron star merger origin was proposed. However, we report the detection of a background galaxy at z=3.2 at the location of EP250207b. Assuming this galaxy is the actual host galaxy, the rest-frame energetics and timescales of the event change. Furthermore, the available data are not able to rule out the presence of a supernova associated with EP250207b if at this redshift. We model the X-ray, optical, near-infrared and radio light curves using a tophat jet model implemented in Redback and find that they are consistent with an on-axis gamma ray burst afterglow. The energetics and host galaxy properties do not allow us to distinguish between a collapsar and a merger driven event.
Comments7 pages, 6 figures, 1 table. Version submitted to MNRAS
