标题： 窄线射电星系的紫外光谱偏振度研究 显示英文标题

标题： UV Spectropolarimetry of Narrow-line Radio Galaxies

摘要： 我们展示了两个低红移窄线射电星系（NLRGs）的紫外光谱偏振（2000 - 3000Å）和远紫外光谱（1500 - 2000Å）的结果，这些数据是利用哈勃太空望远镜（HST）上的暗弱目标光谱仪获取的。 对几个NLRGs的偏振光谱研究表明，通过偏振通量光谱中存在宽允许线，可以发现隐藏的类星体，它们可以通过散射光看到。 成像偏振测量表明，包括我们的目标在内的许多NLRGs通常具有几kpc到>~10 kpc尺度的大散射区域。 这引发了关于这些射电星系中散射物性质的问题。 它们的偏振连续谱的光谱指数与类星体相似或不比类星体蓝，这有利于电子作为主要的散射粒子。 然而，大散射区域的尺寸更倾向于尘埃散射，因为与电子相比，尘埃的散射效率更高。 在本文中，我们结合了我们的紫外数据和以前的光学/红外偏振测量数据，研究了宽波长范围内的偏振通量光谱。 我们推断，散射通常是由NLRGs中的不透明尘云引起的，这是看起来灰色散射的原因之一。 在高红移射电星系中，这些不透明云可能是HST图像中推测出的原星系子结构。 然而，我们仍然不能排除电子散射的可能性，这可能意味着这些射电星系周围存在大量的气体质量。 显示英文摘要

摘要： We present the results of UV spectropolarimetry (2000 - 3000A) and far-UV spectroscopy (1500 - 2000A) of two low-redshift narrow-line radio galaxies (NLRGs) taken with the Faint Object Spectrograph onboard the Hubble Space Telescope (HST). Spectropolarimetry of several NLRGs has shown that, by the presence of broad permitted lines in polarized flux spectrum, they have hidden quasars seen through scattered light. Imaging polarimetry has shown that NLRGs including our targets often have large scattering regions of a few kpc to >~10 kpc scale. This has posed a problem about the nature of the scatterers in these radio galaxies. Their polarized continuum has the spectral index similar to or no bluer than that of quasars, which favors electrons as the dominant scattering particles. The large scattering region size, however, favors dust scattering, because of its higher scattering efficiency compared to electrons. In this paper, we investigate the polarized flux spectrum over a wide wavelength range, combining our UV data with previous optical/infrared polarimetry data. We infer that the scattering would be often caused by opaque dust clouds in the NLRGs and this would be a part of the reason for the apparently grey scattering. In the high-redshift radio galaxies, these opaque clouds could be the proto-galactic subunits inferred to be seen in the HST images. However, we still cannot rule out the possibility of electron scattering, which could imply the existence of a large gas mass surrounding these radio galaxies.