不寻常的射电星系MRC B1221-423：在射电和光波长上探测更深处
The extraordinary radio galaxy MRC B1221-423: probing deeper at radio and optical wavelengths
摘要：
本文介绍了紧凑型陡谱射电源MRC B1221-423（z=0.1706）的光谱和高分辨率多波长射电观测。MRC B1221-423是一个非常年轻（约10^5年）的强大射电源，正在与一个伴星系发生潮汐相互作用。我们发现了活动星系核与其周围环境相互作用的有力证据。射电形态高度扭曲，显示出射电喷流和宿主星系之间的戏剧性相互作用，喷流几乎被转向自身。H I观测表明，与恒星速度相比，在~250 km/s的下落速度下，对核的强烈吸收，以及第二个更广泛的成分，其可能代表落入核中的气体。光谱显示，恒星形成正在整个系统中发生。核中的宽光发射线显示出外流的证据。我们的观测证实MRC B1221-423是一个在富含气体的核环境中的年轻射电源，并且在恒星形成的开始和活动星系核的触发之间有几个亿年的时间延迟。
英文摘要：
We present optical spectra and high-resolution multi-wavelength radio observations of the compact steep-spectrum radio source MRC B1221-423 (z=0.1706). MRC B1221-423 is a very young (~10^5 yr), powerful radio source which is undergoing a tidal interaction with a companion galaxy. We find strong evidence of interaction between the AGN and its environment. The radio morphology is highly distorted, showing a dramatic interaction between the radio jet and the host galaxy, with the jet being turned almost back on itself. H I observations show strong absorption against the nucleus at an infall velocity of ~250 km/s compared to the stellar velocity, as well as a second, broader component which may represent gas falling into the nucleus. Optical spectra show that star formation is taking place across the whole system. Broad optical emission lines in the nucleus show evidence of outflow. Our observations confirm that MRC B1221-423 is a young radio source in a gas-rich nuclear environment, and that there was a time delay of a few x 100 Myr between the onset of star formation and the triggering of the AGN.
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