LEAPS-MPS: Investigating Metallicity and Stellar Age Effects on X-ray Binary Populations

该奖项全部或部分由《2021年美国救援计划法案》（公法117-2）资助。x射线双星（XRBs）由一颗中子星或黑洞组成，这些中子星或黑洞正在积极地从一颗邻近的伴星吸收气体；这种吸积导致了x射线的发射。特别令人感兴趣的是高质量x射线双星（hmxb），其中伴星的质量超过太阳的8倍，因为它们将成为双黑洞或中子星，当它们合并时能够产生可探测的引力波。XRBs辐射的高能光子也可以加热星系的储气层，足以“刹车”恒星形成，特别是在高红移占主导地位的小型、金属贫乏的星系中。此外，来自第一代恒星的hmxb可能有助于早期宇宙的再电离。因此，XRBs在星系的形成和演化中发挥了重要作用。为了更好地理解XRBs，需要评估它们是如何受到其环境的年龄和金属丰度的影响的。该项目将在具有化学丰度、恒星形成历史（SFH）和年龄范围的本地星系样本中描述XRB种群，以评估任何此类依赖。该提案将支持每年指导两名本科生研究人员，以及一个天文学暑期学校（加州理工学院PASS），每年将培训大约10名本科生，全部来自代表性不足或边缘化的群体。由首席研究员（PI）和学生们进行的研究将确定XRB x射线亮度函数（XLF）的详细形状，同时控制环境金属丰度、SMH和恒星年龄，在邻近的四八个星系中使用多波长档案数据。XLF的形状预计会随着金属丰度和恒星年龄的变化而演变，以及在局部低质量、低金属丰度星系中HMXB形成效率的大量（和随机）变化，这些星系与高红移发现的年轻星系类似。了解XLF的形状和XRB尺度关系中固有的散射对于约束XRB种群合成模型（例如，详细的星系演化模拟），更清晰地理解恒星形成在宇宙时间上的抑制，以及更好地理解这些物体如何促进宇宙的再电离将是重要的。这项leap - mps研究计划首次在亚千兆巴尺度上对XRBs及其环境进行了系统研究。丰富的、公开的邻近星系观测档案为加州波莫纳理工学院的本科生参与研究提供了额外的机会。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). X-ray binaries (XRBs) consist of a neutron star or black hole that is actively accreting gas from a close companion star; this accretion is responsible for the emission of X-rays. Of particular interest are high-mass X-ray binaries (HMXBs), in which the companion star is more than 8 times the Sun's mass, as these will become binary black holes or neutron stars, capable of producing detectable gravitational waves when they merge. The high-energy photons radiated by XRBs can also heat a galaxy's gas reservoir sufficiently to "act as a brake" on star formation, particularly in the small, metal poor galaxies that dominate at high redshift. Moreover, HMXBs from the first generation of stars likely helped reionize the early universe. XRBs have thus played a significant role in the formation and evolution of galaxies. A better understanding of XRBs requires an appraisal of how they are affected by the age and metallicity of their environment. This project will characterize XRB populations in a sample of local galaxies having a range of chemical abundance, star formation history (SFH), and age to assess any such dependence. The proposal will support the mentoring of two undergraduate researchers each year, as well as an astronomy summer school (Cal Poly PASS) that will train roughly ten undergraduates per year, all drawn from under- represented or marginalized groups.Research carried out by the principal investigator (PI) and students will determine the detailed shape of the XRB X-ray luminosity function (XLF) while controlling for environmental metallicity, SMH, and stellar age for individual XRBs within forth-eight nearby galaxies using multiwavelength archival data. The shape of the XLF is expected to evolve with metallicity and stellar age, along with substantial (and stochastic) variations in HMXB formation efficiency in local low-mass, low- metallicity galaxies that serve as analogs to the young galaxies found at high redshift. Understanding the XLF shape and scatter inherent in XRB scaling relations will be important for constraining XRB population synthesis models used in (e.g.) detailed galaxy evolution simulations, a clearer understanding of star formation suppression over cosmic time, and for a better sense of how these objects contribute to the reionization of the universe. This LEAPS-MPS research program represents the first systematic study of XRBs and their environments on sub-kiloparsecscales. The rich, publicly available archival observations of nearby galaxies provide additional opportunities for undergraduate students at Cal Poly Pomona to participate in research.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.