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.
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.
Original language | English |
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Article number | A49 |
Number of pages | 16 |
Journal | Astronomy & Astrophysics |
Volume | 597 |
Early online date | 21 Dec 2016 |
DOIs | |
Publication status | Published - Jan 2017 |
Keywords
- Gravitational lensing: micro
- Techniques: photometric
- Quasars: general