Heavy binary black holes in the making: constraining the physics of chemically homogeneous evolution using gravitational waves and electro-magnetic surveys of local analogues

正在形成的重双黑洞：利用引力波和局部类似物的电磁勘测来约束化学均匀演化的物理原理

• 批准号: 2009131
• 负责人: Charles Conroy
• 金额: $ 41.55万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2009131&HistoricalAwards=false
• 关键词: Heavy; binary; black; holes; making

Gravitational wave searches are now detecting the mergers of binary black holes and neutron stars (very compact stellar remnants) at a rate of almost one per week. Arguably, the biggest surprise is the detection of very heavy binary black holes with masses more than thirty times that of the Sun, well in excess of the known black hole binaries in our galaxy. A research group at Harvard University will carry out a theoretical investigation to help understand how these heavy binary black holes form. The scientists expect to learn more about the lives and deaths of massive stars, which are important in the history of the Milky Way and other galaxies, since they produce many of the chemical elements and influence their surroundings by emitting ionizing radiation and outflows. The lead researchers also plan to modernize STEM education through the development of a hands-on computer lab that will make direct use of the data and software that result from the project, and work to increase in participation of women and minorities in theoretical and computational astrophysics, through efforts that are supported by, and complementary to, the project. The two most popular ideas to explain the how heavy black holes are made are (i) the classic common envelope scenario and (ii) the dynamical formation scenario. Both are promising in some ways, but also face serious challenges and open questions. This research project will investigate a third possibility called the chemically homogeneous scenario, in which the stars in the system are very close at birth. Such stars are tidally deformed and believed to be prone to instabilities that cause chemical mixing. This supplies the nuclear burning regions with extra fuel and leads to very compact massive helium stars, which eventually collapse into black holes. The principal investigator and a graduate student will conduct an extensive theoretical investigation of this channel. The primary aim is to provide predictions that can be used to constrain the scenario by comparison with observations of the properties of local populations of massive near-contact binaries (periods, mass ratios, and surface abundances). The secondary aim is to compare with existing and future gravitational wave observations (merger rates, distributions of masses and mass ratios, effective spins, eccentricities, and orbital variations). The team hopes that these efforts will lead to the first solid constraints or upper limits on how much this channel contributes to the massive black hole population and on the physics that drives this channel. This project 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.

引力波搜索现在正在以几乎每周一次的速度探测双黑洞和中子星（非常致密的恒星遗迹）的合并。可以说，最大的惊喜是发现了非常重的双星黑洞，其质量超过太阳的三十倍，远远超过了我们银河系中已知的双黑洞。哈佛大学的一个研究小组将进行一项理论研究，以帮助了解这些重双黑洞是如何形成的。 科学家们希望更多地了解大质量恒星的生命和死亡，这在银河系和其他星系的历史中非常重要，因为它们产生许多化学元素，并通过发射电离辐射和外流影响周围环境。 主要研究人员还计划通过开发一个动手计算机实验室来实现 STEM 教育现代化，该实验室将直接使用该项目产生的数据和软件，并努力增加女性和少数族裔对理论和计算天体物理学的参与，通过该项目支持和补充的努力。 解释黑洞的重量的两个最流行的想法是（i）经典的共同包络情景和（ii）动态形成情景。两者在某些方面都充满希望，但也面临着严峻的挑战和悬而未决的问题。 该研究项目将研究第三种可能性，称为化学均质场景，其中系统中的恒星在诞生时非常接近。这些恒星会发生潮汐变形，并且被认为容易出现导致化学混合的不稳定现象。这为核燃烧区域提供了额外的燃料，并形成非常致密的大质量氦星，最终坍缩成黑洞。 首席研究员和一名研究生将对这个通道进行广泛的理论研究。主要目的是通过与大规模近接触双星的当地特征（周期、质量比和表面丰度）的观测结果进行比较，提供可用于限制情景的预测。 第二个目的是与现有和未来的引力波观测进行比较（合并率、质量分布和质量比、有效自旋、偏心率和轨道变化）。研究小组希望这些努力能够对这个通道对大量黑洞种群的贡献以及驱动这个通道的物理原理产生第一个严格的限制或上限。该项目推进了 NSF 宇宙之窗大创意的目标。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

The Locations of Features in the Mass Distribution of Merging Binary Black Holes Are Robust against Uncertainties in the Metallicity-dependent Cosmic Star Formation History

• DOI: 10.3847/1538-4357/acbf51
• 发表时间: 2022-09
• 期刊: The Astrophysical Journal
• 作者: L. V. van Son;S. D. de Mink;M. Chruslinska;C. Conroy;R. Pakmor;L. Hernquist

The Redshift Evolution of the Binary Black Hole Merger Rate: A Weighty Matter

• DOI: 10.3847/1538-4357/ac64a3
• 发表时间: 2021-10
• 期刊: The Astrophysical Journal
• 作者: L. V. van Son;S. D. de Mink;T. Callister;S. Justham;M. Renzo;T. Wagg;F. Broekgaarden;F. Kummer;R. Pakmor;I. Mandel

No Peaks without Valleys: The Stable Mass Transfer Channel for Gravitational-wave Sources in Light of the Neutron Star–Black Hole Mass Gap

• DOI: 10.3847/1538-4357/ac9b0a
• 发表时间: 2022-09
• 期刊: The Astrophysical Journal
• 作者: L. V. van Son;S. D. de Mink;M. Renzo;S. Justham;E. Zapartas;K. Breivik;T. Callister;W. Farr