The Expanding Radio Lobe of 3C 84 Revealed by VSOP Observations

The expansion and inner proper motions of a young radio lobe associated with the bright radio source 3C 84 in the Seyfert galaxy NGC 1275 have been detected by VSOP observations. These proper motions are consistent with the evolution scenario of classical double radio sources. The apparent expansion velocity is (0.50 +/- 0.09) c. The age of the radio lobe is estimated to be (45.7 +/- 8.9) yr in 2001, which is in agreement with the age previously estimated by Romney et al. (1982). The total flux density at 5 GHz increased at the end of the 1950's, marked several peaks in the middle of: the 1980's, and is presently in a decay phase. The decay of the total flux density can naturally be explained by an adiabatic cooling due to expansion of the radio lobe, and previously measured spectral indices Suggest that the emission comes from the surface of the radio lobe.

通过甚长基线干涉测量空间天文台（VSOP）的观测，在赛弗特星系NGC 1275中与亮射电源3C 84相关联的一个年轻射电瓣的膨胀和内部自行已被探测到。这些自行与经典双射电源的演化情景相符。视膨胀速度为（0.50±0.09）c。2001年，该射电瓣的年龄估计为（45.7±8.9）年，这与罗姆尼等人（1982年）先前估计的年龄一致。5吉赫的总流量密度在20世纪50年代末增加，在20世纪80年代中期出现几个峰值，目前处于衰减阶段。总流量密度的衰减可以自然地用射电瓣膨胀导致的绝热冷却来解释，先前测量的光谱指数表明辐射来自射电瓣的表面。