Low-frequency study of two giant radio galaxies: 3C 35 and 3C 223
Low-frequency study of two giant radio galaxies: 3C 35 and 3C 223
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两个巨型射电星系的低频研究：3C 35 和 3C 223
DOI：
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发表时间：
2010
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通讯作者：
Naval Reserach Laboratory
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作者：
E. Orrú;M. Murgia;L. Feretti;F. Govoni;G. Giovannini;W. Lane;N. Kassim;R. Astro;P. Physics;U. Innsbruck;R. Nijmegen;I. Cagliari;I. D. Radioastronomia;D. A. U. Bologna;Naval Reserach Laboratory
目标。射电星系的投影线性尺寸大于1 Mpc的被归类为巨射电源。根据目前的解释，这些是在低密度环境介质中演化的古老来源。由于辐射损失在低频率下可以忽略不计，因此在此频率范围内扩展光谱老化研究将使我们能够确定注入的零年龄电子光谱，然后提高对源的同步加速器年龄的估计。方法.我们目前在74 MHz和327 MHz的两个巨大的无线电源：3C 35和3C 223甚大阵列图像。我们使用74，327，608和1400 GHz的图像进行了光谱研究。沿源沿着不同位置估计谱形状。结果无线电频谱在热点区域遵循幂律，而在波瓣的内部区域，频谱的形状在高频处显示出曲率。这种变陡与发射相对论电子的同步加速老化一致。为了估计源的同步辐射年龄，用同步辐射模型拟合光谱。结果表明，3C 35是一个年龄为1.43 ± 20亿年的老源，而3C 223是一个年龄为7.2 ± 4亿年的年轻源。
Aims. Radio galaxies with a projected linear size >1 Mpc are classified as giant radio sources. According to the current interpretation these are old sources which have evolved in a low-density ambient medium. Because radiative losses are negligible at low frequency, extending spectral aging studies in this frequency range will allow us to determine the zero-age electron spectrum injected and then to improve the estimate of the synchrotron age of the source. Methods. We present Very Large Array images at 74 MHz and 327 MHz of two giant radio sources: 3C 35 and 3C 223. We performed a spectral study using 74, 327, 608 and 1400 GHz images. The spectral shape is estimated in different positions along the source. Results. The radio spectrum follows a power-law in the hotspots, while in the inner region of the lobe the shape of the spectrum shows a curvature at high frequencies. This steepening agrees with synchrotron aging of the emitting relativistic electrons. In order to estimate the synchrotron age of the sources, the spectra were fitted with a synchrotron model of emission. They show that 3C 35 is an old source of 143 ± 20 Myr, while 3C 223 is a younger source of 72 ± 4M yr.