SN 2021yfj类事件前身的双白矮星并合模型
The double white dwarf merger model for the progenitors of SN 2021yfj-like events
AI总结：
本研究提出双白矮星并合模型，确定形成SN 2021yfj类事件的白矮星与氦伴星初始质量范围，计算其并合率，为该类超新星的前身起源提供重要理论模型。
AI中文摘要：
背景：近期发现一类具有显著Si、S、Ar窄发射特征的新型超新星，即SN 2021yfj类事件（Ien型超新星），其前身起源仍未知。有研究提出，大质量碳氧白矮星（CO WD）以高质量转移率吸积富氦物质时，可能演化成富Si/S白矮星；若该氦伴星后续演化成另一颗质量更大的白矮星，此双白矮星系统的并合可通过潮汐剥离产生富Si/S的星周介质（CSM），超新星爆发后，超新星抛射物与该富Si/S CSM的相互作用，可产生SN 2021yfj类事件特有的Si、S、Ar发射线。目的：本研究旨在确定可通过双白矮星并合场景形成SN 2021yfj类事件的WD+氦星系统的初始参数空间，并量化其理论银河系出生率与延迟时间分布。方法：对大量半接型WD+氦星系统开展详细双星演化模拟，获取可形成富Si/S白矮星及后续双白矮星并合的参数空间；再通过双星种群合成计算此类事件的银河系出生率与延迟时间分布。结果：研究发现，形成SN 2021yfj类事件的初始CO WD与氦伴星质量需分别处于1.0-1.2 M☉与2.2-2.5 M☉范围内；该场景推导的并合率约为(2.6-4.4)×10^-5 yr^-1，延迟时间超过4.5亿年，约为观测到的Ia型超新星率的1%。结论：研究表明，源自CO WD+氦星系统的富Si/S白矮星参与的双白矮星并合场景，是SN 2021yfj类事件的重要且具竞争力的模型，强调需对同类事件开展进一步观测并结合相关理论研究。
英文摘要：
Context. Recently, a new class of supernovae with prominent narrow emission features of Si, S and Ar has been reported, i.e. SN 2021yfj-like events (SNe Ien). Their progenitor origin is still unknown. It has been suggested that a massive CO WD may evolve into a Si/S-rich WD when accreting He-rich matter at a high mass-transfer rate. If the He companion subsequently evolves into another more massive WD, the merger of this double WD system can generate Si/S-rich CSM through tidal stripping. Following the SN explosion, the interaction between the SN ejecta and the Si/S-rich CSM could produce the Si, S, and Ar emission lines characteristic of SN 2021yfj-like events. Aims. In this work, we aim to determine the initial parameter space of WD+He star systems that can lead to SN 2021yfj-like events via the double WD merger scenario, and to quantify their theoretical Galactic birthrate and delay-time distributions. Methods. We perform detailed binary evolution simulations of a large number of semidetached WD+He star systems to obtain the parameter space that leads to the formation of Si/S-rich WDs and subsequent double WD mergers. We then use binary population synthesis to calculate the Galactic birthrate and delay-time distribution of such events. Results. For the formation of SN 2021yfj-like events, we found that the initial CO WD and He companion masses must lie in the ranges of 1.0-1.2 M_sun and 2.2-2.5 M_sun, respectively. The derived merger rate for this scenario is ~(2.6-4.4)x10^-5 yr^-1 with delay times longer than 450 Myr, which is about 1% of the observed SN Ia rate. Conclusions. We suggest that the double WD merger scenario involving a Si/S-rich WD originating from a CO WD+He star system, represents a significant and competitive model for SN 2021yfj-like events, underscoring the need for further observations of similar events coupled with relevant theoretical investigations.
