MiNDSTEp differential photometry of the gravitationally lensed quasars WFI 2033-4723 and HE 0047-1756: microlensing and a new time delay^⋆

¹ Astronomisches Rechen-Institut, Zentrum für Astronomie, Universität Heidelberg, Mönchhofstraße 12-14, 69120 Heidelberg, Germany
e-mail: emanuela@ari.uni-heidelberg.de
² Qatar Environment and Energy Research Institute (QEERI), HBKU, Qatar Foundation, Doha, Qatar
³ Department of Astronomy, Boston University, 725 Commonwealth Avenue, Boston, MA 02215, USA
⁴ Niels Bohr Institute & Centre for Star and Planet Formation, University of Copenhagen Øster Voldgade 5, 1350 Copenhagen, Denmark
⁵ Departamento de Ciencias Físicas, Universidad Andres Bello, Avenida República 220, Santiago, Chile
⁶ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
⁷ Dipartimento di Fisica “E. R. Caianiello”, Università di Salerno, via Giovanni Paolo II 132, 84084 Fisciano (SA), Italy
⁸ Istituto Nazionale di Fisica Nucleare, Sezione di Napoli, 80126 Napoli, Italy
⁹ European Southern Observatory, Karl-Schwarzschild-Straße 2, 85748 Garching bei München, Germany
¹⁰ SUPA, University of St Andrews, School of Physics & Astronomy, North Haugh, St Andrews, KY16 9SS, UK
¹¹ Centre for Electronic Imaging, Dept. of Physical Sciences, The Open University, Milton Keynes MK7 6AA, UK
¹² NASA Ames Research Center, Moffett Field, CA 94035, USA
¹³ Istituto Internazionale per gli Alti Studi Scientifici (IIASS), Vietri Sul Mare (SA), Italy
¹⁴ Institut d’Astrophysique et de Géophysique, Université de Liège, Allée du 6 Août, Bât. B5c, 4000 Liège, Belgium
¹⁵ Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
¹⁶ Institut für Astrophysik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
¹⁷ Subaru Telescope, National Astronomical Observatory of Japan, 650 North Aohoku Place, Hilo, HI 96720, USA
¹⁸ Main Astronomical Observatory, Academy of Sciences of Ukraine, Zabolotnoho 27, 03680 Kyiv, Ukraine
¹⁹ Stellar Astrophysics Centre, Department of Physics & Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark
²⁰ Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries vej30, 2100 Copenhagen Ø, Denmark
²¹ Department of Astronomy, Ohio State University, 140 W. 18th Ave., Columbus, OH 43210, USA
²² Korea Astronomy & Space Science Institute (KASI), 305-348 Daejeon, Republic of Korea
²³ National Space Institute, Technical University of Denmark, 2800 Lyngby, Denmark
²⁴ Jodrell Bank Centre for Astrophyics, University of Manchester, UK
²⁵ Bellatrix Astronomical Observatory, Center for Backyard Astrophysics, Ceccano (FR), Italy
²⁶ Centro de Astro-Ingeniería, Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 7820436 Macul, Santiago, Chile
²⁷ Physics Department, Sharif University of Technology, Tehran, Iran
²⁸ Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, Ontario N2L 2Y5, Canada
²⁹ Observatorio Astronómico Nacional, Instituto de Astronomía – Universidad Nacional Autónoma de México, Ap. P. 877, Ensenada, BC 22860, Mexico
³⁰ Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife, Spain
³¹ Space Telescope Science Institute (STScI), USA
³² Planetary and Space Sciences, Department of Physical Sciences, The Open University, Milton Keynes, MK7 6AA, UK
³³ Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
³⁴ Astrophysics Group, Keele University, Newcastle-under Lyme, ST5 5BG, UK
³⁵ Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, Kunming 650011, PR China
³⁶ NASA Exoplanet Science Institute, MS 100-22, California Institute of Technology, Pasadena, CA 91125, USA
³⁷ Dipartimento di Fisica e Astronomia, Università di Bologna, viale Berti Pichat 6/2, 40127 Bologna, Italy
³⁸ Millennium Institute of Astrophysics, Chile
³⁹ Universidad de La Laguna, Departmento de Astrofísica, 38206 La Laguna, Tenerife, Spain
⁴⁰ Armagh Observatory, College Hill, BT61 9 DG Armagh, UK
⁴¹ Yunnan Observatories, Chinese Academy of Sciences, Kunming 650216, PR China

Received: 22 September 2015
Accepted: 21 September 2016

Abstract

Aims. We present V and R photometry of the gravitationally lensed quasars WFI 2033-4723 and HE 0047-1756. The data were taken by the MiNDSTEp collaboration with the 1.54 m Danish telescope at the ESO La Silla observatory from 2008 to 2012.

Methods. Differential photometry has been carried out using the image subtraction method as implemented in the HOTPAnTS package, additionally using GALFIT for quasar photometry.

Results. The quasar WFI 2033-4723 showed brightness variations of order 0.5 mag in V and R during the campaign. The two lensed components of quasar HE 0047-1756 varied by 0.2–0.3 mag within five years. We provide, for the first time, an estimate of the time delay of component B with respect to A of Δt = (7.6 ± 1.8) days for this object. We also find evidence for a secular evolution of the magnitude difference between components A and B in both filters, which we explain as due to a long-duration microlensing event. Finally we find that both quasars WFI 2033-4723 and HE 0047-1756 become bluer when brighter, which is consistent with previous studies.