Probing Accretion and Relativistic Jet Physics with the Dynamic Multimessenger Universe

用动态多信使宇宙探测吸积和相对论喷流物理

• 批准号: RGPIN-2021-04001
• 负责人: Sivakoff, Gregory
• 金额: $ 3.64万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=742811
• 关键词: Probing; Accretion; Relativistic; Jet; Physics

The physical processes by which most matter accumulates onto astrophysical objects, accretion, are intimately tied to a second set of physical processes, outflows. Astrophysicists call the most highly focused outflows "jets." Most observed jets in our Universe involve processes that accelerate populations of both individual electrons and the bulk outflow of particles to relativistic speeds (i.e., speeds near that of light). Accretion and relativistic jets lead to bright electromagnetic signals. Accretion is often bright at X--ray wavelengths. And relativistic jets are bright at near--infrared through radio wavelengths. Sources undergoing outbursts of accretion and astrophysical jets serve as beacons for both extreme-detail studies in our Galaxy and en masse, lesser-detail studies across the observable Universe. Despite knowing of such sources for more than 50 years, we still cannot answer: "What process or processes accelerate jets?; What differentiates how different types of jets are launched?; and What is the precise role of these sources in galaxy formation?". My long-term goal is to answer these critical questions that apply to objects ranging from individual stars as they are being born to black holes billions of times as massive as the Sun sitting at the centre of galaxies. Given the broad gamut of source types, understanding the connection between accretion and jets is a high--priority goal in astrophysics. Astrophysicists have recently linked astrophysical jets with the first extragalactic events that we can study with non-electromagnetic signals (e.g., signals from high-speed particles, like neutrinos, and gravitational waves). To probe the physics connecting accretion and jets and better understand multi-messenger sources, astrophysicists must measure the properties of jets and, where possible, tie these to properties of accretion. My short-term research program will exploit multiple avenues of time--domain observations across the electromagnetic spectrum to provide these data and theoretical interpretations. I will combine: 1) nearly--simultaneous timing and imaging observations across the electromagnetic spectrum of actively accreting stellar-mass black holes and neutron stars using sets of international facilities (including National Research Council of Canada or Canadian Space Agency co-supported facilities); 2) surveys that reveal the radio and X--ray properties of large numbers of astrophysical objects that will enable my group to identify the nature of these objects, constrain the properties of entire populations, and motivate detailed followup of the most extreme objects; and 3) lead the Canadian multi--messenger astrophysics community's radio response to neutrino and gravitational wave events. I will train 1 Postdoctoral Fellow, 3 Ph.D. students, 4 M.Sc students, and 5 undergraduate students. I will also host 5 South African graduate students for three-month visits to Canada for scientific training.

大多数物质积累到天体物理物体上的物理过程，即吸积，与第二组物理过程，即流出密切相关。天体物理学家将这种高度集中的外流称为“喷流”。在我们的宇宙中观察到的大多数喷流都涉及将单个电子的数量和粒子的大量流出加速到相对论速度(即，接近光速的速度)的过程。吸积和相对论喷流导致明亮的电磁信号。在X射线波长上，吸积物通常是明亮的。相对论喷流在近红外射电波段是明亮的。经历吸积和天体物理喷流爆发的源为我们银河系中的极端详细研究和整个可观测宇宙中较小细节的研究提供了指路明灯。尽管50多年前就知道了这样的源，我们仍然不能回答：“是什么过程加速了喷流？不同类型的喷流是如何发射的？这些源在星系形成中的确切作用是什么？”我的长期目标是回答这些关键问题，这些问题适用于从诞生时的单个恒星到位于星系中心的质量为太阳数十亿倍的黑洞。考虑到源类型的广泛范围，了解吸积和喷流之间的联系是天体物理学的一个高度优先的目标。天体物理学家最近将天体物理喷流与我们可以用非电磁信号(例如，来自高速粒子的信号，如中微子和引力波)研究的第一批河外事件联系起来。为了探索吸积和喷流之间的物理联系，并更好地理解多信使来源，天体物理学家必须测量喷流的性质，并在可能的情况下，将其与吸积性质联系起来。我的短期研究计划将利用电磁频谱中的多个时间域观测方法来提供这些数据和理论解释。我将结合：1)利用成套国际设施(包括加拿大国家研究理事会或加拿大航天局共同支持的设施)，对正在吸积的恒星质量的黑洞和中子星的电磁频谱进行几乎同步的定时和成像观测；2)进行揭示大量天体的射电和X射线特性的调查，这将使我的团队能够确定这些天体的性质，约束整个种群的属性，并激发对最极端天体的详细后续研究；3)领导加拿大多信使天体物理界对中微子和引力波事件的射电响应。我将培养1名博士后，3名博士生，4名硕士研究生和5名本科生。我还将接待5名南非研究生，对加拿大进行为期3个月的科学培训。