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: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=644721
• 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。虽然量子理论已经以极高的精度得到了证实，但广义相对论的精确度要低几个数量级，而且据推测需要修改。因此，广义相对论的检验是最重要的。我们将使用空间超长基线干涉测量（空间VLBI）任务RadioAstron对广义相对论进行最精确的测试。RadioAstron航天器在地球周围的偏心轨道上运行，远地点约35万公里，近地点约2万公里，船上有一个非常稳定的频率标准，氢脉波激射器。与来自地面的氢脉泽信号相比，氢脉泽信号将在其轨道上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。我们将测量引力红移的相对不确定度小至2x10-5，这是迄今为止所有此类广义相对论测试中最小的。***我们将进一步使用RadioAstron与地面上的VLBI天线网络一起对紧凑型射电源进行成像。我们将以前所未有的方式观察脉冲星，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射电发射物理学的理解。我们将把重点放在M81*上，它是附近螺旋星系M81的核心，与半人马座A一起，是最近的星系外AGN，因此可以用无与伦比的线性分辨率进行研究。***我们将继续研究巨大的核心坍缩超新星（SNe）。我们是一个团队的一部分，通过多波长方法研究长时间伽马射线暴（grb）和Ibc型SNe（剥离包络）的联系。如果这类超新星在射电中足够强，我们将领导VLBI观测。GRB与相对论性膨胀有关，因此vlbi确定的膨胀率对于研究GRB - SN Ibc之间的联系非常重要。我们将继续研究SNe II型，确定膨胀和减速，以获得喷发物的密度分布和发射区域的冲击介质和性质信息。将SNe的射电横向膨胀与光学径向膨胀结合起来，可以从几何角度确定到宿主星系的距离，并有助于测量H0。我们将对SN壳层进行高分辨率成像，并寻找恒星死亡的尸体、年轻的中子星或黑洞环境的辐射。射电图像的序列将用于我们的视频系列：“一颗爆炸的恒星的电影。