Test of gravitational redshift and galactic and extragalactic compact radio sources with the technique of very long baseline interferometry

利用甚长基线干涉技术测试引力红移和河道及河外紧凑型射电源

• 批准号: RGPIN-2016-05279
• 负责人: Bartel, Norbert
• 金额: $ 1.97万
• 依托单位: York University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=681971
• 关键词: Test; gravitational; redshift; galactic; extragalactic

Quantum theory and general relativity are the two pillars of modern physics. However, they are incompatible. While quantum theory has been confirmed at an extremely high level of accuracy, general relativity has been confirmed at several orders of magnitude less accuracy -and is speculated to need modification. Tests of general relativity are therefore of primary interest. We will use the space-very-long-baseline interferometry (space VLBI) mission RadioAstron for the most accurate test of general relativity. The RadioAstron spacecraft is on an eccentric orbit around Earth with an apogee of ~350,000 km and a perigee of ~20,000 km, and has an extremely stable frequency standard on board, a hydrogen maser. The hydrogen maser signal will experience the varying gravitational redshift in its orbit when compared with a signal from hydrogen masers from the ground. Measuring the gravitational redshift is a test of the equivalence principle and considered one of the three classical tests of general relativity. We will measure the gravitational redshift with a relative uncertainty as small as 2x10-5, the smallest of any such tests of general relativity yet.***We will further use RadioAstron together with a VLBI network of antennas on the ground to image compact radio sources. We will observe pulsars and probe the size and distance of the scattering material in the interstellar medium in a way never possible before. We will measure active galactic nuclei (AGNs) of radio galaxies and quasars and probe our understanding of the physics of radio emission near supermassive black holes. We will focus on M81*, the core of the nearby spiral galaxy M81 which harbours, together with Cen A, the nearest extragalactic AGN and can therefore be studied with unsurpassed linear resolution. ***We will continue to investigate massive core-collapse supernovae (SNe). We are part of a team to study through a multi-wavelength approach the connection of long-duration gamma-ray-bursts (GRBs) and SNe of Type Ibc (stripped envelope). We will lead VLBI observations of such SNe if they are sufficiently strong in the radio. GRB's are associated with relativistic expansion and VLBI-determined expansion rates are therefore important for the study of the GRB - SN Ibc connection. We will continue to study SNe Type II and determine the expansion and deceleration to obtain information on density profiles of the ejecta and the shocked media and properties of the emission region. Combining the radio transverse expansion with the optical radial expansion of the SNe will allow a geometric determination of the distance to the host galaxy and contribute to a measurement of H0. We will image the SN shell with high resolution and search for emission from the environment of the corpse of the stellar death, a young neutron star or a black hole. The sequence of the radio images will be used for our video series: "A movie of an exploding star."**

量子理论和广义相对论是现代物理学的两大支柱。然而，它们是不相容的。虽然量子理论已被证实在一个非常高的精度水平，广义相对论已被证实在几个数量级的精度-并推测需要修改。因此，广义相对论的检验是人们最感兴趣的。我们将利用空间甚长基线干涉测量（空间VLBI）使命射电天文学对广义相对论进行最精确的检验。RadioAstron航天器位于绕地球的偏心轨道上，远地点约为350，000公里，近地点约为20，000公里，其上有一个极其稳定的频率标准，即氢脉泽。氢脉泽信号在其轨道上与来自地面的氢脉泽信号相比将经历不同的引力红移。测量引力红移是对等效原理的检验，被认为是广义相对论的三个经典检验之一。我们将以2x 10 -5的相对不确定度测量引力红移，这是迄今为止对广义相对论的任何此类测试中最小的。我们将进一步使用射电天文与VLBI地面天线网络一起对紧凑的射电源进行成像。我们将以一种前所未有的方式观测恒星，并探测星际介质中散射物质的大小和距离。我们将测量射电星系和类星体的活动星系核（AGN），并探索我们对超大质量黑洞附近无线电发射物理学的理解。我们将重点关注M81*，它是附近旋涡星系M81的核心，与Cen A一起拥有最近的河外活动星系核，因此可以用无与伦比的线性分辨率进行研究。* 我们将继续研究大质量核心坍缩超新星（SNe）。我们是一个团队的一部分，通过多波长方法研究长持续时间伽马射线暴（GRB）和Ibc型SNe（剥离信封）的连接。 我们将领导VLBI观测这样的SNe，如果他们在无线电足够强。GRB与相对论膨胀有关，因此VLBI确定的膨胀率对于研究GRB - SN Ibc联系是重要的。我们将继续研究SNe II型，并确定膨胀和减速，以获得有关喷出物和冲击介质的密度分布和发射区域的属性的信息。将SNe的射电横向膨胀与光学径向膨胀相结合，将允许几何确定到宿主星系的距离，并有助于测量H 0。我们将对SN壳层进行高分辨率成像，并寻找来自恒星死亡尸体、年轻中子星星或黑洞环境的辐射。无线电图像的序列将用于我们的视频系列：“一个爆炸的星星的电影。"**