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

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具有极高的精确度，但广义相对论被证实的精确度要低几个数量级--据推测需要修改。因此，对广义相对论的检验是最重要的。我们将使用空间甚长基线干涉测量(SPACE VLBI)任务无线电Astron进行最精确的广义相对论测试。RadioAstron航天器在绕地球的偏心轨道上，远地点约35万公里，近地点约20000公里，船上有一个极其稳定的频率标准，即氢脉泽。与来自地面的氢脉泽信号相比，氢脉泽信号在其轨道上将经历不同的引力红移。测量引力红移是对等价原理的检验，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，测量的相对不确定度小到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和地面的VLBI天线网络来成像紧凑的射电源。我们将以一种前所未有的方式观察脉冲星，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射电发射的物理理解。我们将聚焦于M81*，这是附近螺旋星系M81的核心，它与CEN A一起，是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塌缩超新星(SNE)。我们是通过多波长方法研究长持续时间伽马射线暴(GRB)和IBC(剥离包络)SNE之间联系的团队的一员。如果这种SNE在无线电中足够强，我们将领导对它们的VLBI观测。伽玛暴与相对论膨胀有关，因此VLBI确定的膨胀率对于研究伽玛暴-SN IBC连接是很重要的。我们将继续研究第二类近地天体，并确定膨胀和减速，以获得关于抛射物和冲击介质的密度分布以及发射区的性质的信息。将射电横向扩展和近地天体的光学径向扩展结合起来，将允许几何地确定到宿主星系的距离，并有助于测量H0。我们将以高分辨率成像SN壳层，并搜索恒星死亡身体、年轻中子星或黑洞环境中的辐射。这一系列的无线电图像将用于我们的视频系列：“一部恒星爆炸的电影。”**

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."**