COSMOGRAIL

XVIII. time delays of the quadruply lensed quasar WFI2033−4723^⋆

¹ Institute of Physics, Laboratory of Astrophysics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Observatoire de Sauverny, 1290 Versoix, Switzerland
e-mail: vivien.bonvin@epfl.ch
² Max Planck Institute for Astrophysics, Karl-Schwarzschild-Str. 1, 85740 Garching, Germany
³ Physik-Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
⁴ Institute of Astronomy and Astrophysics, Academia Sinica, 11F of ASMAB, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan
⁵ Subaru Telescope, National Astronomical Observatory of Japan, 650 N Aohoku Pl, Hilo 96720, Japan
⁶ Department of Physics, University of California, Davis, CA 95616, USA
⁷ STAR Institute, Quartier Agora – Allée du six Août 19c, 4000 Liège, Belgium
⁸ Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa, Chiba 277-8583, Japan
⁹ National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
¹⁰ Department of Physics and Astronomy, PAB, 430 Portola Plaza, Box 951547 Los Angeles, CA 90095, USA
¹¹ Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, 452 Lomita Mall, Stanford, CA 94035, USA
¹² Fermi National Accelerator Laboratory, PO Box 500 Batavia, IL 60510, USA
¹³ Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637, USA
¹⁴ Departamento de Ciencias Físicas, Universidad Andres Bello Fernandez Concha 700, Las Condes, Santiago, Chile
¹⁵ Centro de Astroingeniería, Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, Macul 7820436 Santiago, Chile
¹⁶ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
¹⁷ Las Cumbres Observatory Global Telescope, 6740 Cortona Dr., Suite 102, Goleta, CA 93111, USA
¹⁸ Department of Physics, University of California, Santa Barbara, CA 93106-9530, USA
¹⁹ Instituto de Física y Astronomía, Universidad de Valparaíso, Avda. Gran Bretaña 1111, Playa Ancha, Valparaíso 2360102, Chile
²⁰ Millennium Institute of Astrophysics, Chile
²¹ Department of Physics, United States Naval Academy, 572C Holloway Rd., Annapolis, MD 21402, USA
²² Argelander-Institut für Astronomie, Auf dem Hügel 71, 53121 Bonn, Germany
²³ Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA
²⁴ Center for Cosmology and Astroparticle Physics, The Ohio State University, 191 W. Woodruff Avenue, Columbus, OH 43210, USA

Received: 20 May 2019
Accepted: 11 June 2019

Abstract

We present new measurements of the time delays of WFI2033−4723. The data sets used in this work include 14 years of data taken at the 1.2 m Leonhard Euler Swiss telescope, 13 years of data from the SMARTS 1.3 m telescope at Las Campanas Observatory and a single year of high-cadence and high-precision monitoring at the MPIA 2.2 m telescope. The time delays measured from these different data sets, all taken in the R-band, are in good agreement with each other and with previous measurements from the literature. Combining all the time-delay estimates from our data sets results in Δt_AB = 36.2^+0.7_−0.8 days (2.1% precision), Δt_AC = −23.3^+1.2_−1.4 days (5.6%) and Δt_BC = −59.4^+1.3_−1.3 days (2.2%). In addition, the close image pair A1-A2 of the lensed quasars can be resolved in the MPIA 2.2 m data. We measure a time delay consistent with zero in this pair of images. We also explore the prior distributions of microlensing time-delay potentially affecting the cosmological time-delay measurements of WFI2033−4723. Our time-delay measurements are not precise enough to conclude that microlensing time delay is present or absent from the data. This work is part of a H0LiCOW series focusing on measuring the Hubble constant from WFI2033−4723.