Title: eROSITA-selection of new period-bounce Cataclysmic Variables: First follow-up confirmation using TESS and SDSS Show Chinese title

Title: eROSITA选择新的周期反弹灾变变星：首次利用TESS和SDSS的后续确认

Abstract: Between 40$\%$ and 80$\%$ of cataclysmic variables (CVs) are expected to have evolved past the period-minimum and contain a degenerate donor. However, observational surveys for CVs have only been able to detect a few of these highly evolved "period-bouncers", most likely due to the intrinsic faintness associated with their predicted low mass accretion rates. We have produced an initial selection of 137 high-likelihood period-bounce candidates from WD catalog based on our multiwavelength period-bouncer scorecard and selection cuts including X-ray data from the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) on board the Spektrum-Roentgen-Gamma spacecraft (SRG). We have laid out three main requirements (classification as a CV, determination of an orbital period and detection of a very late-type donor) that should result in the confirmation of several of these candidates. Our path for confirming these candidates has already produced its first successful result with the confirmation of GALEX J125751.4-283015 as a new period-bouncer. Several other candidates have already fulfilled at least one of our three requirements making their future confirmation likely. Our search for period-bouncers using the X-ray eROSITA emission of objects in optical WD catalogs has led to the confirmation of six new period-bouncers identified from the Gaia DR3 WD catalog (five previously known CVs and one WD candidate), a 18$\%$ increase that brings the present population to 39 systems. Both the selection method for period-bounce candidates and the confirmation path that we outlined will aid in future searches for new period-bounce candidates, contributing to the goal of resolving the discrepancy between the predicted high number of period-bouncers and the low number of these systems successfully observed to date. Show Chinese abstract

Abstract: 在40$\%$到80$\%$的爆发变星（CVs）中，预计有部分已经演化过了周期最小值，并包含一个简并的供体。 然而，对CVs的观测调查只能够检测到其中少数几个高度演化的“周期反弹者”，这很可能是由于它们预测的低质量吸积率所带来的固有暗淡性。 我们基于多波段周期反弹者评分卡和选择标准（包括安装在Spektrum-Roentgen-Gamma航天器（SRG）上的成像望远镜阵列扩展X射线巡天（eROSITA）的X射线数据）从白矮星目录中生成了一个初步的137个高可能性周期反弹者候选列表。 我们提出了三个主要要求（分类为CV、确定轨道周期和检测非常晚型的供体），这些要求应该能够确认其中的几个候选者。 我们确认这些候选者的路径已经取得了第一个成功结果，即确认GALEX J125751.4-283015为一个新的周期反弹者。 其他几个候选者已经满足了我们三个要求中的至少一个，使其未来确认的可能性很大。 我们利用光学白矮星目录中天体的X射线eROSITA发射进行周期反弹者的搜索，已经确认了六个新的周期反弹者，这些反弹者来自Gaia DR3白矮星目录（五个之前已知的CVs和一个白矮星候选者），这一数量增加了18$\%$，使目前的系统总数达到39个。 我们提出的周期反弹者选择方法和确认路径将有助于未来寻找新的周期反弹者候选者，从而有助于解决预测的周期反弹者高数量与至今成功观测到的低数量之间的差异。