标题： VLBI测量长期光行差漂移 显示英文标题

标题： VLBI measurement of the secular aberration drift

摘要： 在分析数十年的甚长基线干涉测量(VLBI)数据时，我们检测到了由于太阳系质心围绕银河系中心旋转而引起的河外射电源自行运动的长期折射漂移。 我们的结果与预测的估计值一致，为每年4-6微角秒（{\mu }as/yr），指向{\alpha } = 266\circ 和{\delta } = -29\circ 。 此外，我们尝试检测速度场的四极系统误差。 分析方法包括三个步骤。 首先，我们分析了大地测量和天体测量VLBI数据，以生成射电源坐标时间序列。 其次，我们将555个源在1990-2010年期间长时间观测历史的自行运动拟合到各自的时间序列上。 最后，我们将一阶和二阶矢量球谐成分拟合到自行运动场。 在误差范围内，偶极分量的大小和方向与预测结果一致。 偶极矢量的幅度为6.4 \pm 1.5 {\mu }as/yr，并指向赤道坐标 {\alpha } = 263\circ 和 {\delta } = -20\circ 。 四极分量尚未被探测到。 在小于10-9 Hz的频率范围内积分的原初引力波密度有一个上限为0.0042 h-2，其中h是归一化的哈勃常数，即H0/(100 km s-1)。 显示英文摘要

摘要： While analyzing decades of very long baseline interferometry (VLBI) data, we detected the secular aberration drift of the extragalatic radio source proper motions caused by the rotation of the Solar System barycenter around the Galactic center. Our results agree with the predicted estimate to be 4-6 micro arcseconds per year ({\mu}as/yr) towards {\alpha} = 266\circ and {\delta} = -29\circ. In addition, we tried to detect the quadrupole systematics of the velocity field. The analysis method consisted of three steps. First, we analyzed geodetic and astrometric VLBI data to produce radio source coordinate time series. Second, we fitted proper motions of 555 sources with long observational histories over the period 1990-2010 to their respective coordinate time series. Finally, we fitted vector spherical harmonic components of degrees 1 and 2 to the proper motion field. Within the error bars, the magnitude and the direction of the dipole component agree with predictions. The dipole vector has an amplitude of 6.4 \pm 1.5 {\mu}as/yr and is directed towards equatorial coordinates {\alpha} = 263\circ and {\delta} = -20\circ. The quadrupole component has not been detected. The primordial gravitational wave density, integrated over a range of frequencies less than 10-9 Hz, has a limit of 0.0042 h-2 where h is the normalized Hubble constant is H0/(100 km s-1).