HST observations of eight intrinsically luminous quasars with redshiftsbetween $0.16$ and~$0.29$ are presented. Seven companion galaxies brighter than$M_V = -16.5$ lie within a projected distance of 25 kpc of the quasars; threeof the companions are located closer than $3''$ (6 kpc projected distance) fromthe quasars, well within the volume that would be enclosed by a typical $L^*$host galaxy. The observed association of quasars and companion galaxies isstatistically significant and may be an important element in theluminous-quasar phenomenon. Evidence for candidate host galaxies is presentedfor the three most promising cases: PG 1116+215, 3C 273, and PG 1444+407, butadditional observations are required before the characteristics of thecandidate hosts can be regarded as established. Upper limits are placed on thevisual-band brightnesses of representative galactic hosts for all of thequasars. These limits are established by placing galaxy images obtained withHST underneath the quasars and measuring at what faintness level the knowngalaxies are detected. On average, the HST spirals would have been detected ifthey were one magnitude fainter than $L^*$ or brighter and the early-typegalaxies could have been detected down to a brightness level of about $L^*$,where $L^*$ is the Schechter characteristic luminosity of field galaxies.
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机译：给出了HST观测到的8个内在发光类星体的红移在0.16美元和0.29美元之间。亮度超过$ M_V = -16.5 $的七个伴星系位于预计的25 kpc类星体距离内；其中三个伴星离类星体的距离小于$ 3''$（投影距离为6 kpc），处于典型的$ L ^ * $宿主星系所包围的体积之内。观测到的类星体和伴星系之间的联系具有统计学意义，并且可能是发光类星体现象的重要因素。给出了三种最有希望的情况的候选宿主星系的证据：PG 1116 + 215、3C 273和PG 1444 + 407，但是在可以认为候选宿主的特征被确立之前还需要进行其他观察。对所有类星体，代表性银河系宿主的可见波段亮度设置了上限。通过将用HST获得的星系图像放置在类星体下面并测量检测到已知星系的模糊程度，可以建立这些限制。平均而言，如果HST螺旋线比$ L ^ * $更微弱或更亮，并且可以检测到早期类型的星系到大约$ L ^ * $的亮度水平，则将检测到HST螺旋，其中$ L ^ * $是星系星系的Schechter特征光度。
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