Young stars and scattered light in the powerful radio galaxy 3C 321
Young stars and scattered light in the powerful radio galaxy 3C 321
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强大的射电星系 3C 321 中的年轻恒星和散射光
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
M. Shaw
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文献类型：
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作者：
C. Tadhunter;R. Dickson;M. Shaw
本文给出了低红移射电星系3C321(z=0.096)的蓝偏振光谱观测结果。研究发现，从紫外线到光学波段的偏振百分比显著下降--从观测覆盖的最短波长到最长波长下降了5倍--偏振角在垂直于射电轴的15°范围内。这些结果与散射活动星系核的存在是一致的，该散射活动星系核组成了紫外线连续谱的20%-70%，但在光学波长上被旧恒星群的光稀释了。用类星体+E星系或幂定律+E星系来模拟连续谱能量分布的尝试通常在大部分光谱上都能很好地拟合，但在其余波长范围3900-4300 A范围内与模型相比有明显的过剩。最适合的模型包括类星体、I-Gyr星暴、15Gyr恒星群和星云连续体，在3639A时，这些成分分别贡献了总通量的22%、34%、34%和10%。总体而言，我们的结果强调了强大射电星系的光学紫外连续体的多分量性质。本文给出了低红移射电星系3C321(z=0.096)的蓝偏振光谱观测结果。研究发现，从紫外线到光学波段的偏振百分比显著下降--从观测覆盖的最短波长到最长波长下降了5倍--偏振角在垂直于射电轴的15°范围内。这些结果与散射活动星系核的存在是一致的，该散射活动星系核组成了紫外线连续谱的20%-70%，但在光学波长上被旧恒星群的光稀释了。用类星体+E星系或幂定律+E星系来模拟连续谱能量分布的尝试通常在大部分光谱上都能很好地拟合，但在其余波长范围3900-4300 A范围内与模型相比有明显的过剩。最适合的模型包括类星体、I-Gyr星暴、15Gyr恒星群和星云连续体，在3639A时，这些成分分别贡献了总通量的22%、34%、34%和10%。总体而言，我们的结果强调了强大射电星系的光学紫外连续体的多分量性质。大范围的变化表明偏振测量；相邻波长箱的角度测量在误差范围内一致。
Blue spectropolarimetry observations are presented for the low-redshift radio galaxy 3C 321 (z = 0.096). The percentage polarization is found to show a spectacular decline from the UV to the optical - by a factor of 5 from the shortest to the longest wavelengths covered by the observations - and the polarization angle is within 15° of the perpendicular to the radio axis. These results are consistent with the presence of a scattered AGN component which comprises 20-70 per cent of the UV continuum, but is diluted by the light of the old stellar populations at optical wavelengths. Attempts to model the continuum spectral energy distribution in terms of quasar + E-galaxy or power-law + E-galaxy produce generally good fits over much of the spectrum, but there is a significant excess over the models in the rest wavelength range 3900-4300 A. This excess, and the detection of the higher order Balmer lines in absorption, provides strong evidence for the presence of a population of young (A-type) stars. The best-fitting model comprises a combination of a quasar, a I-Gyr starburst, a 15-Gyr-old stellar population and nebular continuum, with these components contributing 22, 34, 34 and 10 per cent of the total flux at 3639 A respectively. Overall, our results serve to emphasize the multicomponent nature of the opticallUV continuum of powerful radio galaxies. ABSTRACT Blue spectropolarimetry observations are presented for the low-redshift radio galaxy 3C 321 (z = 0.096). The percentage polarization is found to show a spectacular decline from the UV to the optical - by a factor of 5 from the shortest to the longest wavelengths covered by the observations - and the polarization angle is within 15° of the perpendicular to the radio axis. These results are consistent with the presence of a scattered AGN component which comprises 20-70 per cent of the UV continuum, but is diluted by the light of the old stellar populations at optical wavelengths. Attempts to model the continuum spectral energy distribution in terms of quasar + E-galaxy or power-law + E-galaxy produce generally good fits over much of the spectrum, but there is a significant excess over the models in the rest wavelength range 3900-4300 A. This excess, and the detection of the higher order Balmer lines in absorption, provides strong evidence for the presence of a population of young (A-type) stars. The best-fitting model comprises a combination of a quasar, a I-Gyr starburst, a 15-Gyr-old stellar population and nebular continuum, with these components contributing 22, 34, 34 and 10 per cent of the total flux at 3639 A respectively. Overall, our results serve to emphasize the multicomponent nature of the opticallUV continuum of powerful radio galaxies. large-scale variations suggest polarization measures; angle measure for adjacent wavelength bins consistent within the errors.