标题： 诱导的星系形成和极高红移射电星系的形态演化 显示英文标题

标题： Induced star formation and morphological evolution in very high redshift radio galaxies

摘要： 近红外、亚角秒分辨率的图像，使用W. M. Keck I望远镜获得，显示在高红移射电星系（HzRGs）中，其静止框架光学波长处的形态有显著演化，这些星系的红移范围为1.9<z<4.4。结构从z>3时的大尺度低表面亮度区域，周围环绕着明亮的多组分且常与射电对齐的特征，转变为z<3时更紧凑和对称的形状。z>3 HzRGs中的单个组分的线性尺寸（约10 kpc）和光度（M_B~-20至-22）类似于在z=3-4时看到的正常、无射电活动的恒星形成星系的总尺寸和光度。`R'波段、0.1角秒分辨率的图像，使用哈勃空间望远镜拍摄的其中一个HzRGs，4C41.17在z=3.800时显示，在静止框架紫外波长下，星系形态分解为更小的、约1 kpc大小的组分，嵌入在一个大范围的低表面亮度发射晕中。最亮的紫外辐射来自一个与射电对齐的、边缘增亮的特征（4C41.17-北），位于一个明亮的射电结下游。也使用HST获得的窄带Lyman-alpha图像显示，在同一位置有一个弧形的Lyman-alpha特征，暗示了强喷流/云碰撞。使用W. M. Keck II望远镜对4C41.17进行的深部偏振光谱观测显示，与射电对齐的紫外连续谱是无偏振的。（摘要） 显示英文摘要

摘要： Near-infrared, sub-arcsecond seeing images obtained with the W. M. Keck I Telescope of show strong evolution at rest--frame optical} wavelengths in the morphologies of high redshift radio galaxies (HzRGs) with 1.9<z<4.4. The structures change from large--scale low surface brightness regions surrounding bright, multiple component and often radio--aligned features at z>3, to much more compact and symmetrical shapes at z<3. The linear sizes (~10 kpc) and luminosities (M_B~-20 to -22) of the individual components in the z>3 HzRGs are similar to the total sizes and luminosities of normal, radio--quiet, star forming galaxies seen at z=3--4. `R'-band, 0.1 arcsec resolution images with the Hubble Space Telescope of one of these HzRGs, 4C41.17 at z=3.800, show that at rest--frame UV wavelengths the galaxy morphology breaks up in even smaller, ~1 kpc--sized components embedded in a large halo of low surface brightness emission. The brightest UV emission is from a radio--aligned, edge-brightened feature (4C41.17-North) downstream from a bright radio knot. A narrow--band Lyman-alpha image, also obtained with HST, shows an arc--shaped Lyman-alpha feature at this same location, suggestive of a strong jet/cloud collision. Deep spectropolarimetric observations with the W. M. Keck II Telescope of 4C41.17 show that the radio--aligned UV continuum is unpolarized. (abridged)