High-z Universe probed via Lensing by QSOs (HULQ)

II. Deep GMOS spectroscopy of a QSO lens candidate

¹ Physics and Astronomy Department, University of California, Los Angeles, CA 90095-1547, USA
e-mail: yctaak@astro.ucla.edu
² SNU Astronomy Research Center, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
e-mail: myungshin.im@gmail.com
³ Astronomy Program, Department of Physics & Astronomy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
⁴ Department of Astronomy and Atmospheric Sciences, College of Natural Sciences, Kyungpook National University, Daegu 41566, Republic of Korea
⁵ Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, PR China
⁶ Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea

Received: 7 October 2021
Accepted: 20 June 2022

Abstract

Galaxies and their central supermassive black holes are known to coevolve, but the physical background for this is unknown as of yet. The High-z Universe probed via Lensing by QSOs (HULQ) project aims to investigate this coevolution by using quasi-stellar object (QSO) host galaxies acting as gravitational lenses (QSO lenses). We present the results of the spectroscopic observation of the first QSO lens candidate from the HULQ project, HULQ J0002+0239, which consists of a QSO host galaxy at z_d = 1.455 and four seemingly lensed objects in a cross-like configuration. Deep optical spectra of two of the possibly lensed objects with z ∼ 24.5 mag were obtained with the Gemini Multi-Object Spectrograph on the Gemini North Telescope. Their spectra reveal that the objects are newly discovered galaxies at z = 0.29 and z = 1.11, and we conclude that HULQ J0002+0239 is not a QSO lens. Our QSO lens search results are so far in agreement with the predicted number of QSO lenses, and we discuss how the future investigation of additional QSO lens candidates could tell us more about the evolution of the black hole mass and host galaxy scaling relations.