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.

引力波搜索现在以几乎每周一次的速度探测到双星黑洞和中子星(非常致密的恒星残骸)的合并。可以说，最令人惊讶的是探测到了质量超过太阳30倍的非常重的双星黑洞，远远超过了我们银河系中已知的黑洞双星。哈佛大学的一个研究小组将进行一项理论研究，以帮助了解这些重的双星黑洞是如何形成的。科学家们希望更多地了解大质量恒星的生死，这在银河系和其他星系的历史上非常重要，因为它们产生许多化学元素，并通过释放电离辐射和外流影响周围环境。首席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教育的现代化，该实验室将直接利用该项目产生的数据和软件，并通过该项目支持和补充的努力，努力增加妇女和少数群体对理论和计算天体物理学的参与。解释黑洞是如何形成的最流行的两种想法是(I)经典的公共包络假说和(Ii)动力学形成假说。两者在某些方面都很有希望，但也面临着严峻的挑战和悬而未决的问题。这项研究项目将研究第三种可能性，称为化学均质情景，在这种情景中，系统中的恒星在出生时非常接近。这类恒星是潮汐形变的，被认为容易产生导致化学混合的不稳定性。这为核燃烧区域提供了额外的燃料，并导致非常致密的大质量氦恒星，这些恒星最终坍塌成黑洞。首席调查员和一名研究生将对这一渠道进行广泛的理论调查。其主要目的是提供可用于通过与大量近接触双星的本地种群的特性(周期、质量比和表面丰度)的观测相比较的预测来限制该情景。第二个目的是与现有和未来的引力波观测结果(合并率、质量和质量比的分布、有效自转、偏心率和轨道变化)进行比较。该团队希望，这些努力将导致对该通道对大规模黑洞数量的贡献以及驱动该通道的物理学的第一个坚实的限制或上限。这个项目推进了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。

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