VDES J2325-5229：一个利用形态无关监督机器学习发现的z=2.7引力透镜类星体
星系天体物理
2017-01-11 v2
摘要
我们报告了一个引力透镜类星体的发现及其初步表征，其源红移z_s=2.74，像间距为2.9角秒，由前景红移z_l=0.40的椭圆星系透镜化。由于引力透镜类星体的图像是多个点源与前景透镜星系的叠加，我们开发了一种基于高斯混合模型监督机器学习的、形态无关的多波段测光选择透镜类星体候选体的方法。利用该技术以及来自暗能量巡天(DES)的gi多色测光观测、VISTA半球巡天(VHS)的近红外JK测光和WISE中红外测光，我们识别出一个候选系统，其两个星表成分的i_AB星等分别为18.61和20.44，由一个椭圆星系和两个蓝色点源组成。使用NTT进行光谱跟踪及利用一份存档的AAT光谱表明，这些点源可被识别为一个透镜类星体，其发射线红移为z=2.739±0.003，以及一个前景早型星系，红移为z=0.400±0.002。我们将该系统建模为单个等温椭球，得出爱因斯坦半径θ_E∼1.47角秒，包围质量M_enc∼4×10^11 M_⊙，时间延迟约52天。相对较大的像间距、月尺度的时间延迟时长以及高红移，使得该系统成为约束红移大于1处宇宙膨胀率的理想对象。
引用
@article{arxiv.1607.01391,
title = {VDES J2325-5229 a z=2.7 gravitationally lensed quasar discovered using morphology independent supervised machine learning},
author = {Fernanda Ostrovski and Richard G. McMahon and Andrew J. Connolly and Cameron A. Lemon and Matthew W. Auger and Manda Banerji and Johnathan M. Hung and Sergey E. Koposov and Christopher E. Lidman and Sophie L. Reed and Sahar Allam and Aurélien Benoit-Lévy and Emmanuel Bertin and David Brooks and Elizabeth Buckley-Geer and Aurelio Carnero Rosell and Matias Carrasco Kind and Jorge Carretero and Carlos E. Cunha and Luiz N. da Costa and Shantanu Desai and H. Thomas Diehl and Jörg P. Dietrich and August E. Evrard and David A. Finley and Brenna Flaugher and Pablo Fosalba and Josh Frieman and David W. Gerdes and Daniel A. Goldstein and Daniel Gruen and Robert A. Gruendl and Gaston Gutierrez and Klaus Honscheid and David J. James and Kyler Kuehn and Nikolay Kuropatkin and Marcos Lima and Huan Lin and Marcio A. G. Maia and Jennifer L. Marshall and Paul Martini and Peter Melchior and Ramon Miquel and Ricardo Ogando and Andrés Plazas Malagón and Kevin Reil and Kathy Romer and Eusebio Sanchez and Basilio Santiago and Vic Scarpine and Ignacio Sevilla-Noarbe and Marcelle Soares-Santos and Flavia Sobreira and Eric Suchyta and Gregory Tarle and Daniel Thomas and Douglas L. Tucker and Alistair R. Walker},
journal= {arXiv preprint arXiv:1607.01391},
year = {2017}
}
备注
11 pages, 7 figures, 7 tables, MNRAS accepted