射电星系和类星体的统一方案被观测到的尺寸分布证伪
Unification scheme of radio galaxies and quasars falsified by their observed size distributions
摘要：
在目前流行的基于方向的统一方案中，当射电星系的主射电轴恰好在观测者视线周围的某个圆锥开口角内时，射电星系就表现为类星体。由于几何投影，类星体的观测尺寸因此应该看起来比射电星系小。我们表明，这个简单的，明确的预测的统一方案是不支持的射电星系和类星体的实际观测角的大小。除了在最初的3CR样本中，在此基础上提出的统一方案，在其他更大的样本中，射电星系和类星体的大小分布没有统计上的显着差异是明显的。低激发射电星系的人口显然没有隐藏的类星体内，这可能解释观测到的无线电星系在低红移的数量过多，仍然不能解释没有任何的类星体的大小在大的红移缩短。另一方面，从红外线和X射线研究中，有证据表明，在许多RG中的尘埃环内隐藏着类星体，在$z>0.5$。似乎很难将这一点与即使在这些红移下类星体的大小也没有透视缩短相协调，也许人们不得不承认射电主轴可能与环面的光轴没有任何关系。否则，要解决射电星系和类星体的二分法，可能需要一个与现在完全不同的方案。
英文摘要：
In the currently popular orientation-based unified scheme, a radio galaxy appears as a quasar when its principal radio-axis happens to be oriented within a certain cone opening angle around the observer's line of sight. Due to geometrical projection, the observed sizes of quasars should therefore appear smaller than those of radio galaxies. We show that this simple, unambiguous prediction of the unified scheme is not borne out by the actually observed angular sizes of radio galaxies and quasars. Except in the original 3CR sample, based on which the unified scheme was proposed, in other much larger samples no statistically significant difference is apparent in the size distributions of radio galaxies and quasars. The population of low-excitation radio galaxies with apparently no hidden quasars inside, which might explain the observed excess number of radio galaxies at low redshifts, cannot still account for the absence of any foreshortening of the sizes of quasars at large redshifts. On the other hand from infrared and X-ray studies there is evidence of hidden quasar within a dusty torus in many RGs, at $z>0.5$. It seems difficult how to reconcile this with the absence of foreshortening of quasar sizes at even these redshifts, and perhaps one has to allow that the major radio axis may not have anything to do with the optical axis of the torus. Otherwise to resolve the dichotomy of radio galaxies and quasars, a scheme quite different from the present might be required.
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