Planck-dust-allsky

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

January 2017 • 2017A&A...597A..49G

Authors • Giannini, E. • Schmidt, R. W. • Wambsganss, J. • Alsubai, K. • Andersen, J. M. • Anguita, T. • Bozza, V. • Bramich, D. M. • Browne, P. • Calchi Novati, S. • Damerdji, Y. • Diehl, C. • Dodds, P. • Dominik, M. • Elyiv, A. • Fang, X. • Figuera Jaimes, R. • Finet, F. • Gerner, T. • Gu, S. • Hardis, S. • Harpsøe, K. • Hinse, T. C. • Hornstrup, A. • Hundertmark, M. • Jessen-Hansen, J. • Jørgensen, U. G. • Juncher, D. • Kains, N. • Kerins, E. • Korhonen, H. • Liebig, C. • Lund, M. N. • Lundkvist, M. S. • Maier, G. • Mancini, L. • Masi, G. • Mathiasen, M. • Penny, M. • Proft, S. • Rabus, M. • Rahvar, S. • Ricci, D. • Scarpetta, G. • Sahu, K. • Schäfer, S. • Schönebeck, F. • Skottfelt, J. • Snodgrass, C. • Southworth, J. • Surdej, J. • Tregloan-Reed, J. • Vilela, C. • Wertz, O. • Zimmer, F.

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.

Based on data collected by MiNDSTEp with the Danish 1.54 m telescope at the ESO La Silla observatory.

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Sebastiano Calchi Novati

Associate Scientist