Ultracompact binaries: Gravitational wave sources and supernova Ia progenitors

对超致密双星(UCBS)的研究是更好地理解晚期双星演化和Ia型超新星(SN)替代路径的关键，UCBS由一对极其接近的白矮星(WD)、中子星(NS)和/或氦恒星组成，后者代表着我们确定银河系外距离尺度和宇宙最终命运(例如宇宙加速)的最佳“标准蜡烛”。银河系UCBS也将被下一代重力波望远镜如ESA/NASA的激光干涉仪空间天线(LISA)常规探测到。德克萨斯理工大学的一个研究小组将对银河系平面在两个半球的快速节奏测量进行分析，以确定数百个新的UCBS的统一样本。这项研究将支持一位博士候选人。首席调查员还将建立一个项目，将研究经验带给服务不足的农村小学、初中和高中生以及教师培训。UCB可以通过其光曲线被检测到，该曲线显示出由于日食或近距离分量的潮汐变形而导致的时间尺度上的短至30分钟的变化。美国国家科学基金会资助的兹维基瞬变设施(ZTF)和BlackGEM阵列是覆盖两个半球的下一代光学时域测量。这项研究将结合来自两者的数据与其他大规模调查，如eROSITA，PanSTARRS，GAIA，和SDSS-V，以编制一个统一的银河面UCBS样本。该项目预计将发现并表征数百个新的UCBS，并预计为数十个系统确定准确的系统参数。大样本将被用来挑战常见的包络和双星演化理论(例如，预测的轨道周期和观测到的轨道周期和组件质量分布)，并计算各种路径的经验SNIa率。他们预计将使已知的LISA可探测来源的数量增加两倍，并将已知的SN Ia前体的数量增加至少一个数量级。预计UCBS将主导LISA可探测到的源，从而产生随机的前景引力波信号。在短期内，确定银河系UCB群体的特征对于寻找最佳设计和数据分析方法，以便LISA自信地探测隐藏在这一“噪声”中的其他引力波源(例如，双星黑洞或白矮星合并)将是重要的。这个项目因此推进了NSF宇宙大理想之窗的目标。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Studies of Ultra-compact binaries (UCBs), consisting of an extremely close pair of white dwarf (WD), neutron star (NS), and/or helium stars, are key to a better understanding of late-stage binary star evolution as well as alternate pathways to Type Ia supernovae (SN), the latter representing our best "standard candle" for determining the extra-galactic distance scale and the ultimate fate of the universe (e.g., cosmic acceleration). Galactic UCBs will also be routinely detected by the next generation of gravity wave telescopes like ESA/NASA's Laser Interferometer Space Antenna (LISA). A research team at Texas Tech University will analyze a fast cadence survey of the Galactic Plane in both hemispheres to identify a uniform sample of several-hundred new UCBs. The research will support a Ph.D. candidate. The principal investigator will also establish a program to bring research experience to underserved and rural elementary, middle, and high-school students plus teacher-training.UCBs can be detected through their light-curves, which show variations on timescales as short as 30-min due to eclipses or tidal deformation of the close components. The NSF-funded Zwicky Transient Facility (ZTF) and the BlackGEM array are the next generation optical time-domain surveys covering both hemispheres. This research will combine data from both with other large-scale surveys, such as eROSITA, PanSTARRS, Gaia, and SDSS-V to compile a uniform sample of Galactic plane UCBs. This project expects to find and characterize a few hundred new UCBs and anticipates the determination of accurate system parameter for a few tens of systems. The large sample will be used to challenge common envelope and binary evolution theories (e.g., predicted vs. observed orbital period and component mass distributions) and calculate empirical SN Ia rates for various pathways. They expect to triple the number of known LISA-detectable sources and increase the number of known SN Ia progenitors by at least an order of magnitude. UCBs are expected to dominate the sources detectable by LISA and will thus create a stochastic foreground gravitational wave signal. Characterizing the Galactic UCB population will be important in the near term for finding optimal design and data analysis methods for LISA to confidently detect other gravitational wave sources (e.g., binary blackhole or white dwarf mergers) hidden in this “noise”. This project thus advances the goals of the NSF Windows on the Universe Big Idea.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.