中等质量黑洞活动星系核的射电连续谱研究:总结与展望

中等质量黑洞活动星系核(intermediate mass black hole active galactic nuclei, IMBH AGN)是指中心黑洞大约在10²M⊙¹0⁶M⊙质量范围的活动星系核。关于近邻宇宙中IMBH AGN的研究,对于理解高红移类星体中的超大质量黑洞起源(即"种子黑洞问题")、低频引力波源等基本问题有着重要意义。得益于近20年来大规模光学光谱巡天的发展,已发现近邻宇宙中的宽线IMBH AGN的数目超过500个。对于这些光学选IMBH AGN,基于VLA FIRST巡天数据,针对小样本或个源的专门射电连续谱观测,已取得不少结果。从射电形态、连续谱谱型、射电功率和射电噪度、黑洞吸积基本面这四个方面,详细地介绍了目前IMBH AGN射电连续谱研究的进展。并且,分别面向当前正在开展的几个SKA探路者大规模连续谱巡天项目,以及大约10年后运行的SKA (至少是SKA一期),展望了IMBH AGN领域将来可以进行研究的科学目标。

Studies on the Radio Continua of Active Galactic Nuclei with Intermediate-mass Black Holes:Summary and Prospect

Active galactic nuclei with intermediate-mass black holes(IMBH AGN) harbor central black holes(BHs) with their masses in the range 10~2 M⊙~10~6 M⊙. They have significant values in studying the origin of the supermassive BHs in high-redshift quasars(namely the seed BHs problem) and the astronomical sources of low-frequency gravitational waves. The number of broad-line IMBH AGN in the local universe, owing to the great development of large-scale optical spectroscopic surveys, has been more than 500. For those optically selected IMBH AGN, the radio studies based on the VLA FIRST survey data and follow-up radio continuum observations of individuals and small samples, have obtained meaningful results already. This article reviews the progresses in the field of radio continua of IMBH AGN, detailed in the following 4 aspects: the radio morphology, continuum slope,radio power and loudness, and fundamental plane of BH activity. Moreover, preparing for the ongoing large-scale continuum surveys as SKA pathfinder projects(eg, VLASS and EMU) and for the SKA era 10 years later(SKA1 at least), we prospect the achievable goals for IMBH AGNs in the pathfinder and SKA eras respectively. Besides, aiming to find low-redshift IMBH AGN out of such a huge number of sources that would be detected by SKA, we analyze and present an optimal strategy of the followup identification(eg, optical spectroscopy for redshifts) for those purely radio-selected sources.