衰落射电星系消退速度远超预期

天文学家近日发现一批正在衰落的射电星系，其中心超大质量黑洞已停止产生强大的射电喷流。1通过对这些remnant射电星系的研究，科学家确认其光谱年龄仅为8至42百万年，中位数约12百万年，远年轻于此前的科学预测。1这一发现表明这类天体的消退速度比原先认知快得多。1

开普敦大学和数据密集型天文学校际研究所的研究人员利用MeerKAT MIGHTEE survey、uGMRT superMIGHTEE survey、LOFAR、GMRT和Jansky Very Large Array等多台望远镜，在144 MHz至1.5 GHz的频率范围内对XMM-LSS场进行观测。1在14个射电星系候选体中，12个被确认为真正的remnant射电星系，2个为活跃源。1研究还发现高红移的remnant星系衰落更为迅速，这解释了为何这些天体难以被观测到。1相关成果已发表在《英国皇家天文学会月刊》2026年第550卷第4期上。1

Astronomers have identified a population of fading radio galaxies whose central supermassive black holes have ceased producing powerful radio jets, revealing that these remnant sources decline much more rapidly than previously understood 1. Analysis of fourteen candidate objects in the XMM-Newton Large-Scale Structure field yielded twelve confirmed remnant radio galaxies and two active sources 1. The spectral ages of these remnant galaxies span only 8 to 42 million years, with a median of approximately 12 million years, considerably younger than anticipated 1.

The research, conducted by teams at the University of Cape Town and the Inter-University Institute for Data-Intensive Astronomy, employed observations from multiple radio surveys including the MeerKAT MIGHTEE survey, the uGMRT superMIGHTEE survey, LOFAR, GMRT, and the Jansky Very Large Array, operating across frequencies from 144 MHz to 1.5 GHz 1. The findings indicate that remnant galaxies at higher redshifts—those at greater distances—fade even more quickly, which explains why these astronomical objects are difficult to detect 1. The results were published in the Monthly Notices of the Royal Astronomical Society in 2026, Volume 550, Issue 4 1.