标题： 宇宙正午的一个候选双重类星体（QSO） 显示英文标题

标题： A Candidate Dual QSO at Cosmic Noon

摘要： 我们报告了在红移z=1.889处一个候选双重类星体的发现，该红移处于被称为“宇宙正午”的时期，在此期间大多数宇宙黑洞和恒星质量的增长发生。 该源是在哈勃太空望远镜WFC3/IR图像中识别出的尘埃变红类星体，显示两个在0.26"投影距离（即2.2千秒差距）上紧密分离的点源。 这个红色类星体被选为目标以探索红色类星体是否由合并星系所主导。 随后，我们获得了该系统的空间分辨STIS光谱，覆盖可见光谱范围，并验证了两个不同的类星体成分的存在。 我们还通过VLBA在1.4 GHz（21厘米L波段）获得高分辨率射电连续波观测，发现了与光学位置一致的两个源。 这些源具有相似的黑洞质量、总辐射功率和射电亮度参数。 然而，它们的颜色和消光程度存在显著差异。 较红的类星体具有更高的爱丁顿比，这与先前的研究结果一致。 我们考虑了引力透镜的可能性，发现这需要极端且不太可能的条件。 如果确认为真正的双重类星体系统，该系统将把尘埃变红与星系和超大质量黑洞合并联系起来，开辟一个新的群体来寻找双重活动星系核样本。 显示英文摘要

摘要： We report the discovery of a candidate dual QSO at z=1.889, a redshift that is in the era known as "cosmic noon" where most of the Universe's black hole and stellar mass growth occurred. The source was identified in Hubble Space Telescope WFC3/IR images of a dust-reddened QSO that showed two closely-separated point sources at a projected distance of 0.26", or 2.2 kpc. This red QSO was targeted for imaging to explore whether red QSOs are hosted by merging galaxies. We subsequently obtained a spatially-resolved STIS spectrum of the system, covering the visible spectral range, and verifying the presence of two distinct QSO components. We also obtained high-resolution radio continuum observations with the VLBA at 1.4 GHz (21-cm L band) and found two sources coincident with the optical positions. The sources have similar black hole masses, bolometric luminosities, and radio loudness parameters. However, their colors and reddenings differ significantly. The redder QSO has a higher Eddington ratio, consistent with previous findings. We consider the possibility of gravitational lensing and and find that it would require extreme and unlikely conditions. If confirmed as a bona-fide dual QSO, this system would link dust-reddening to galaxy and supermassive black hole mergers, opening up a new population in which to search for samples of dual AGN.