Signatures of Shocks and Particle Acceleration from Novae in our Galaxy

银河系新星的冲击和粒子加速特征

• 批准号: 1615084
• 负责人: Brian Metzger
• 金额: $ 34.27万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2020-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1615084&HistoricalAwards=false
• 关键词: Signatures; Shocks; Particle; Acceleration; Novae

1. A nova eruption is a dramatic increase in energy output caused by runaway thermonuclear burning of hydrogen on the surface of a white dwarf star. Ordinarily, a white dwarf (a star with the mass of our Sun crammed into a volume about the size of the Earth) contains little or no hydrogen. If it has an ordinary star as a companion, however, a white dwarf can sometimes accumulate hydrogen from the companion onto its surface. As little as a few ten-thousandths of the mass of our Sun can be enough to trigger the thermonuclear "burning" of this hydrogen fuel. Runaway hydrogen burning produces the observed nova outburst and violently ejects mass from the white dwarf. Recent spacecraft observations have revealed gamma-ray emission during nova outbursts. These observations demonstrate that hydrodynamic shocks occur in novae. This research aims to use computer simulations to study the origin, appearance, and implications of these shocks. The work will greatly improve the understanding of emission at many different wavelengths during nova outbursts. It will also improve scientists? understanding of the acceleration of ions and electrons to extremely high energies. The Intellectual Merit of the work comes from such advances. The involvement of undergraduate students in the research and public outreach through movies and an interactive website are good Broader Impacts of the research.2. Novae are sudden outbursts of energy powered by runaway thermonuclear burning on the surface of a white dwarf that has accreted matter from a stellar companion. The recent discovery of GeV gamma rays emitted during nova outbursts provides a striking indicator that hydrodynamic shocks occur in these systems. This project will employ hydrodynamic calculations to study the origin, appearance, and implications of shocks in novae. The work will also investigate the efficiency of shock acceleration of electrons and ions as well as magnetic-field amplification at the shock. In addition, the combination of numerical simulations and multi-wavelength modelling will be used to constrain various shock parameters. The Intellectual Merit of the research derives from improved understanding of emission from novae and of a mechanism of particle acceleration in astrophysics. The results will also inform both radio and optical surveys for transient phenomena. The Broader Impacts of the work will involve not only research opportunities for undergraduates but also public outreach through an interactive website, color movies, and a workshop for high school teachers.

1.新星爆发是由白色矮星星星表面氢的失控热核燃烧引起的能量输出的急剧增加。 通常情况下，一颗白色矮星（一颗质量与太阳相当的星星，体积与地球相当）几乎不含氢。 然而，如果它有一颗普通的星星作为伴星，白色矮星有时可以从伴星上积累氢到它的表面。 只要我们太阳质量的万分之几就足以引发这种氢燃料的热核“燃烧”。 失控的氢燃烧产生了观测到的新星爆发和来自白色矮星的剧烈喷发物质。 最近的航天器观测揭示了新星爆发期间的伽马射线发射。 这些观测结果表明，流体动力冲击发生在新星。 本研究旨在使用计算机模拟来研究这些冲击的起源，外观和含义。 这项工作将大大提高对新星爆发期间许多不同波长的发射的理解。 它也将提高科学家？理解离子和电子加速到极高能量。 这项工作的智力价值来自于这些进步。 本科生参与研究和通过电影和互动网站进行公众宣传是很好的研究的更广泛的影响。新星是由白色矮星表面失控的热核燃烧提供能量的突然爆发，该矮星从恒星伴星吸积了物质。 最近发现的GeV伽马射线在新星爆发期间发射提供了一个引人注目的指标，流体动力学冲击发生在这些系统。 这个项目将采用流体动力学计算来研究新星中冲击的起源、出现和影响。 这项工作还将研究电子和离子的冲击加速效率以及冲击时的磁场放大。 此外，将使用数值模拟和多波长建模相结合的方法来限制各种冲击参数。 这项研究的智力价值来自于对新星发射和天体物理学中粒子加速机制的更好理解。 结果还将为无线电和光学调查提供信息，以了解瞬态现象。 这项工作的更广泛的影响将不仅涉及本科生的研究机会，而且还通过互动网站，彩色电影和高中教师研讨会进行公众宣传。