The dying accretion and jet in a powerful radio galaxy of Hercules A  

作　　者：Lin-Hui Wu Qing-Wen Wu Jian-Chao Feng Ru-Sen Lu Xu-Liang Fan 

机构地区：[1]School of Physics,Huazhong University of Science and Technology,Wuhan 430074,China [2]School of Physics and Electronic Science,Guizhou Normal University,Guiyang 550001,China [3]Shanghai Astronomical Observatory,Chinese Academy of Science,Shanghai 200030,China [4]Max-Planck-Institut fuir Radioastronomie,Auf dem Higel 69,D-53121 Bonn,Germany [5]School of Mathematics,Physics and Statistics,Shanghai University of Engineering Science,Shanghai 201620,China

出　　处：《Research in Astronomy and Astrophysics》2020年第8期193-200,共8页天文和天体物理学研究（英文版）

基　　金：the National Natural Science Foundation of China(NSFC;Grant Nos.U1931203,11622324,11573009);the Key Program of NSFC(Grant No.11933007);Research Program of Fundamental and Frontier Sciences,Chinese Academy of Sciences(Grant No.ZDBS-LY-SLH011);NSFC(Grant No.11947099);the Science and Technology Foundation of Guizhou Province(QKHJC[2020]1Y018)。

摘　　要：Hercules A(Her A)is one of a rare class of dying and transition-type objects,which has a pair of giant,powerful radio lobes and a weak radio core.We reduce and analyze the radio data of Her A that were observed by the Expanded Very Large Array(EVLA)during 2010-2011 at C band.The intensity distribution is very smooth along the edge of the lobe front and the intensity also sharply decreases at the edge,which supports that magnetic fields may play an important role in radio lobes.The spectrum of the weak core is very steep and the core flux becomes weaker by about ten percent when compared to what was observed twenty years ago,which suggest that the central engine is still dying quickly.Her A deviates a lot from the relation between[O III]luminosity and low-frequency 178 MHz luminosity(LO III-L178 MHz)as defined by other FR I/II sources.However,when only radio core emission is considered,it roughly follows an LO III-L178 MHzcorrelation.This result supports that the black-hole accretion and large-scale jet in Her A did not evolve simultaneously,and indicates that although the large-scale jet is still powerful,the accretion and inner jet have changed into an inactive state.Based on the estimated Bondi accretion rate,we model the spectrum of Her A with a radiatively inefficient accretion flow and jet model.

关 键 词：black hole physics galaxies:jets radiation mechanisms:non-thermal galaxies:magnetic fields radio continuum:galaxies 

分 类 号：P145.8[天文地球—天体物理]