发表机构
University of Science and Technology of China; National Astronomical Observatory of Japan, National Institutes of Natural Sciences; Guizhou University（中国科学技术大学; 日本国立天文台，国立自然科学研究院; 贵州大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
利用WFST和DECam对亚太阳质量致密双星并合候选体S251112cm进行光学对应体搜寻，排除了快速千新星起源，并对快速光学暂现源给出了迄今最强的光学约束。
AI 中文摘要
引力波（GW）源的电电磁对应体可探测致密天体并合的性质、环境和演化。S251112cm属于一类新兴的、可能包含亚太阳质量成分的引力波候选体。我们利用大视场巡天望远镜（WFST）对S251112cm进行了光学对应体搜寻。观测在引力波触发后20.2小时开始，持续三个夜晚，覆盖了约780平方度，占更新后天空图中定位概率的51%。我们搜寻了新出现的、快速演化的、核外光学暂现源，并识别出四个候选体，其宿主星系距离与引力波距离估计大致一致。然而，这四个候选体的演化速度均明显慢于AT 2017gfo，排除了其AT 2017gfo类似起源的可能性，并且不利于它们作为快速演化的千新星对应体与S251112cm相关联。结合WFST和DECam的观测，覆盖的定位概率提高至约67%。在对应体位于该覆盖范围内的条件下，我们约束了一组双中子星千新星模型。对于观测角θ_obs<60°，在其他参数固定为AT 2017gfo的最佳拟合值时，动力学抛射质量M_dyn≳0.01 M_sun或风抛射质量M_wind≳0.05 M_sun的模型在大部分覆盖的引力波概率范围内被排除。超越千新星模型，我们的唯象分析将上升半时T_rise,1/2≤2天的快速演化光学暂现源的峰值绝对星等约束在约-13等以下。据我们所知，协调的WFST和DECam观测为这类涉及亚太阳质量致密天体的新型引力波候选体的可能快速演化对应体提供了迄今最强的光学约束。
英文摘要
Electromagnetic counterparts to gravitational-wave (GW) sources probe the properties, environments, and evolution of compact-object mergers. S251112cm belongs to an emerging class of GW candidates with possible subsolar-mass components. We present an optical counterpart search for S251112cm with the Wide Field Survey Telescope (WFST). The observations began 20.2 hr after the GW trigger and continued for three nights, covering approximately $780~\mathrm{deg}^{2}$ and $51\%$ of the localization probability in the updated skymap. We searched for newly emerging, rapidly evolving, off-nuclear optical transients and identified four candidates whose host-galaxy distances are broadly consistent with the GW distance estimate. However, all four evolve substantially more slowly than AT 2017gfo, ruling out an AT 2017gfo-like origin and disfavoring their association with S251112cm as rapidly evolving kilonova counterparts. Combining WFST and DECam observations increases the covered localization probability to approximately 67%. Conditional on the counterpart lying within this footprint, we constrain a grid of binary-neutron-star kilonova models. For viewing angles $θ_{\rm obs}<60^{\circ}$, with the other parameters fixed to the best-fitting values for AT 2017gfo, models with dynamical ejecta mass $M_{\rm dyn}\gtrsim0.01\,M_{\odot}$ or wind ejecta mass $M_{\rm wind}\gtrsim0.05\,M_{\odot}$ are disfavored over most of the covered GW probability. Beyond kilonova models, our phenomenological analysis constrains rapidly evolving optical transients with $T_{\rm rise,1/2}\leq2$ days to peak absolute magnitudes fainter than approximately -13 mag. To our knowledge, the coordinated WFST and DECam observations provide the strongest optical constraints to date on possible rapidly evolving counterparts to this new class of GW candidates involving subsolar-mass compact objects.
Comments15 pages, 8 figures, 2 tables. Submitted
