摘要
耀变体由星系中央超大黑洞供应强大的能源,由于相对论性束流效应,其喷流的亮度被放大,从而比同等距离的其他天体显得更加明亮,耀变体也由此成为贯穿宇宙漫长演化历程的"灯塔",成为人类解开宇宙奥秘的一把钥匙.即便有增亮的加持,观测宇宙极早期耀变体的难度仍然很高,导致人们对第一代耀变体的认识极为有限.本文利用甚长基线干涉测量技术成功观测到一颗编号为J1430+4204的耀变体,并结合历史数据测量了喷流的运动.该天体生活在约等于宇宙十分之一年龄的时期,记录着宇宙早期的宝贵信息.对J1430+4204以及其他宇宙早期耀变体的研究有助于理解第一代超大黑洞的活动性及其对宿主星系的反馈.
High-resolution observations of high-redshift(z > 4) radio quasars offer a unique insight into jet kinematics at early cosmological epochs, as well as constraints on cosmological model parameters.Due to the general weakness of extremely distant objects and the apparently slow structural changes caused by cosmological time dilation, only a couple of high-redshift quasars(HRQs) have been studied with parsec-scale resolutions, and with limited number of observing epochs. Here we report on very long baseline interferometry(VLBI) observations of a high-redshift blazar J1430 + 4204(z=4.72) in the 8 GHz frequency band at five different epochs spanning 22 years. The source shows a compact core–jet structure with two jet components being identified within 3 milli-arcsecond(mas) scale. The long time span and multiple-epoch data allow for the kinematic studies of the jet components. That results in a jet proper motion of μ(J1) = 0.017 ± 0.002 mas a^-1 and μ(J2) = 0.156 ± 0.015 mas a^-1, respectively. For the fastest-moving outer jet component J2, the corresponding apparent transverse speed is (19.5 ± 1.9) c.The inferred bulk jet Lorentz factor C=14.6 ± 3.8 and viewing angle θ=2.2°± 1.6°indicate highly relativistic beaming. The Lorentz factor and apparent proper motion are the highest measured to date among the z > 4 jetted radio sources, while the jet kinematics is still consistent with the cosmological interpretation of quasar redshifts.
作者
张迎康
安涛
Sándor Frey
Yingkang Zhang;Tao An;Sándor Frey(Shanghai Astronomical Observatory,Chinese Academy of Sciences,Shanghai 200030,China;University of Chinese Academy of Sciences,Beijing 100049,China;Key Laboratory of Radio Astronomy,Chinese Academy of Sciences,Nanjing 210008,China;Konkoly Observatory,Research Centre for Astronomy and Earth Sciences,Konkoly Thege Miklósút 15-17,H-1121 Budapest,Hungary)
基金
This work was supported by the National Key R&D Programme of China(2018YFA0404603)
the Chinese Academy of Sciences(114231KYSB20170003)
the Hungarian National Research,Development and Innovation Office(2018-2.1.14-T T-CN-2018-00001).The authors acknowledge the use of Astrogeo Center database of brightness distributions,correlated flux densities
images of compact radio sources produced with VLBI.YZ thanks Shu Fengchun,Alexey Melnikov,Jamie McCallum,and Bo Xia for providing the Asia-Oceania VLBI(AOV)data and auxiliary telescope system temperature files.
