The Evolution, Influence, and Ultimate Fate of Massive Stars: Transient Phenomena and Stellar Astrophysics in the Era of Wide-Field Surveys

提高对大质量恒星生命周期的理解对天体物理学的每个子领域都有好处。通过电离辐射、强大的恒星风、核合成和超新星（SN）爆炸的死亡，大质量恒星诞生了黑洞和中子星，同时激发了宇宙的动力学和化学演化。尽管对大质量恒星的研究是天文学中最古老的子领域之一，但近年来宽视场时域巡天的出现已经在恒星演化领域引发了一场剧变。通过打开动态天空的新体制，我们发现了新的天文瞬变类型，挑战了我们对大质量恒星的生命和爆炸死亡期间发生的物理过程的看法。我的研究项目的目标是了解大质量恒星的生与死，以及它们与不寻常的天文瞬变起源的关系。我们的基本方法是将瞬态现象的多波长观测与解决恒星群的研究相结合，这将利用下一代宽视场时域调查和引力波设施，以及由高精度光度测定和大规模光谱调查实现的恒星天体物理学的进步。这个项目牢牢地站在各个领域的交汇处，蓄势以待快速发展，它将引领人们全面了解大质量恒星的演化、影响和最终命运。特别是，我们关注三个主要的长期研究目标：(1)多信使引力波天体物理学：我的小组将推进新兴的多信使引力波天体物理学领域，从单个物体到群体研究。我们将讨论中子星合并对宇宙核合成的总贡献等问题。(2)瞬变天文学的新体制：我的小组将使用下一代宽视场时域巡天来全面绘制瞬变的相空间，并进行多波长后续计划，以确定新发现（但可能普遍存在）各种爆炸的性质。我们还将利用对SN的观测来解决恒星物理学中的紧迫问题，例如驱动SN爆炸前质量损失的机制，以及SN爆炸的起源。(3)通过人口统计的恒星天体物理学：我们将推动附近星系中大质量恒星群体的光谱，光度和时间分辨调查的前沿。我们将继续开发新技术，以识别和表征在难以捉摸的阶段演化的大质量恒星。利用这类天体的第一批统计样本，我们将解决一些基本问题——比如爆发质量损失在大质量恒星演化中的作用，以及双星对再电离时代的影响。

An improved understanding of the lifecycle of massive stars benefits every subfield in astrophysics. Through their ionizing radiation, powerful stellar winds, nucleosynthesis, and deaths as supernova (SN) explosions, massive stars give birth to black holes and neutron stars, while stoking the dynamical and chemical evolution of the universe. Although the study of massive stars is one of the oldest subfields in astronomy, the recent advent of wide-field time-domain surveys has launched an upheaval in field of stellar evolution. By opening new regimes of the dynamic sky, we have uncovered new types of astronomical transients, challenging our views of the physical processes that occur during both the lives and explosive deaths of massive stars. The goal of my research program is to understand the life and death of massive stars, and their relation to the origin of unusual astronomical transients. Our fundamental approach is to combine multi-wavelength observations of transient phenomena with studies of resolved stellar populations, which will leverage the next generation of wide-field time-domain surveys and gravitational wave facilities as well as the advances in stellar astrophysics enabled by high-precision photometry and large-scale spectroscopic surveys. Sitting firmly at the intersection of fields poised for rapid progress, this program will lead the development of a comprehensive picture of the evolution, influence, and ultimate fate of massive stars. In particular, we focus on three primary Long-Term Research Objectives: (1) Multi-messenger Gravitational-Wave Astrophysics: My group will advance the burgeoning field of multi-messenger gravitational-wave astrophysics from individual objects to population studies. We will address questions such as total contribution of neutron star mergers to cosmic nucleosynthesis. (2) New Regimes of Transient Astronomy: My group will use the next generation of wide-field time domain surveys to fully map the phase space of transients, and conduct the multi-wavelength follow-up programs to determine the nature of newly discovered (but possibly prevalent) varieties of explosions. We will also use observations of SN to address pressing questions in stellar physics, such as the mechanism that drives explosive pre-SN mass loss, and the progenitors of SN explosions. (3) Stellar Astrophysics via Population Statistics: We will push the frontiers of spectroscopic, photometric, and time-resolved surveys of massive star populations in nearby galaxies. We will continue to develop new techniques to identify and characterize evolved massive stars in elusive phases. Using the first statistical samples of such objects, we will address fundamental questions---such as the role of eruptive mass loss in the evolution of massive stars, and the influence binary stars on the epoch of reionization.