TDCOSMO

II. Six new time delays in lensed quasars from high-cadence monitoring at the MPIA 2.2 m telescope^⋆

¹ Institute of Physics, Laboratory of Astrophysics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Observatoire de Sauverny, 1290 Versoix, Switzerland
e-mail: martin.millon@epfl.ch
² Fermi National Accelerator Laboratory, PO Box 500, Batavia, IL 60510, USA
³ Department of Physics, University of California, Davis, CA 95616, USA
⁴ Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637, USA
⁵ Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, 452 Lomita Mall, Stanford, CA 94035, USA
⁶ Max Planck Institute for Astrophysics, Karl-Schwarzschild-Strasse 1, 85740 Garching, Germany
⁷ Physik-Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
⁸ Institute of Astronomy and Astrophysics, Academia Sinica, PO Box 23-141, Taipei 10617, Taiwan
⁹ Department of Physics and Astronomy, University of California, Los Angeles, CA 90095, USA
¹⁰ Departamento de Ciencias Físicas, Universidad Andres Bello Fernandez Concha 700, Las Condes, Santiago, Chile
¹¹ Millennium Institute of Astrophysics, Chile
¹² Instituto de Física y Astronomía, Universidad de Valparaíso, Avda. Gran Bretaña 1111, Playa Ancha, Valparaíso 2360102, Chile
¹³ DARK, Niels Bohr Institute, University of Copenhagen, Lyngbyvej 2, 2100 Copenhagen, Denmark
¹⁴ Centre for Extragalactic Astronomy, Department of Physics, Durham University, Durham DH1 3LE, UK
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 STAR Institute, Quartier Agora, Allée du six Août, 19c, 4000 Liège, Belgium
¹⁸ Las Cumbres Observatory Global Telescope, 6740 Cortona Dr., Suite 102, Goleta, CA 93111, USA
¹⁹ Department of Physics, University of California, Santa Barbara, CA 93106-9530, USA

Received: 18 June 2020
Accepted: 21 August 2020

Abstract

We present six new time-delay measurements obtained from R_c-band monitoring data acquired at the Max Planck Institute for Astrophysics (MPIA) 2.2 m telescope at La Silla observatory between October 2016 and February 2020. The lensed quasars HE 0047−1756, WG 0214−2105, DES 0407−5006, 2M 1134−2103, PSJ 1606−2333, and DES 2325−5229 were observed almost daily at high signal-to-noise ratio to obtain high-quality light curves where we can record fast and small-amplitude variations of the quasars. We measured time delays between all pairs of multiple images with only one or two seasons of monitoring with the exception of the time delays relative to image D of PSJ 1606−2333. The most precise estimate was obtained for the delay between image A and image B of DES 0407−5006, where τ_AB = −128.4_−3.8^+3.5 d (2.8% precision) including systematics due to extrinsic variability in the light curves. For HE 0047−1756, we combined our high-cadence data with measurements from decade-long light curves from previous COSMOGRAIL campaigns, and reach a precision of 0.9 d on the final measurement. The present work demonstrates the feasibility of measuring time delays in lensed quasars in only one or two seasons, provided high signal-to-noise ratio data are obtained at a cadence close to daily.