捕获的行为：发现一个物理类星体三胞胎
Caught in the Act: Discovery of a Physical Quasar Triplet
摘要：
我们发现了z~1.51的类星体三重态。整个系统在25弧秒（即，预计距离200 kpc）。这三个天体之间的速度差异（通过宽的MgII发射线测量）小于1000 km/s，表明类星体属于相同的物理结构。该领域的宽带近红外图像没有显示星系或星系团可以作为引力透镜的证据，排除了两个或所有三个类星体是单个强透镜源的多个图像的可能性。QQQ J1519+0627是目前已知的第二个类星体。我们估计，这些系统是极其罕见的简单的偶然叠加。缺乏强烈的星系过密性表明，这个奇特的系统隐藏在一个尚未形成的巨大结构的种子中。根据在拉西拉天文台用欧洲南方天文台的新技术望远镜和在卡拉尔阿尔托天文台用西班牙阿莱曼航天中心的3.5米望远镜收集的观测数据。
英文摘要：
We present the discovery of a triplet of quasars at z~1.51. The whole system is well accommodated within 25 arcsec (i.e., 200 kpc in projected distance). The velocity differences among the three objects (as measured through the broad MgII emission line) are less than 1000 km/s, suggesting that the quasars belong to the same physical structure. Broad band NIR images of the field do not reveal evidence of galaxies or galaxy clusters that could act as a gravitational lens, ruling out the possibility that two or all the three quasars are multiple images of a single, strongly lensed source. QQQ J1519+0627 is the second triplet of quasars known up to date. We estimate that these systems are extremely rare in terms of simple accidental superposition. The lack of strong galaxy overdensity suggests that this peculiar system is harboured in the seeds of a yet-to-be-formed massive structure. Based on observations collected at the La Silla Observatory with the New Technology Telescope (NTT) of the European Southern Observatory (ESO) and at the Calar Alto Observatory with the 3.5m telescope of the Centro Astronómico Hispano Alemán (CAHA).
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