Adaptive PSF fitting – a highly performing photometric method and light curves of the GLS H1413+117: time delays and micro-lensing effectsстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 11 апреля 2017 г.
Аннотация:We present new photometric observations of H1413+117 acquired during seasons between 2001 and 2008 in order to estimate the time delays between the lensed quasar images and to characterize at best the on-going micro-lensing events. We propose a highly performing photometric method called the adaptive point spread function fitting and have successfully tested this method on a large number of simulated frames. This has enabled us to estimate the photometric error bars affecting our observational results.We analysed the V- and R-band light curves and V–R colour variations of the A–D components which show short- and long-term
brightness variations correlated with colour variations. Using the χ2 and dispersion methods, we estimated the time delays on the basis of the R-band light curves over the seasons between 2003 and 2006. We have derived the new values: tAB =−17.4 ± 2.1, tAC =−18.9 ± 2.8 and tAD = 28.8 ± 0.7 d using the χ2 method (B and C are leading, D is trailing) with 1σ confidence intervals. We also used available observational constraints (resp. the lensed image positions, the flux ratios in mid-IR and two sets of time delays derived in the present work) to update the lens redshift estimation.We obtained zl = 1.95+0.06
−0.10 which is in good agreement with previous estimations. We propose to characterize two kinds of micro-lensing events: micro-lensing for the A, B, C components corresponds to typical variations of ∼10−4 mag d−1 during all the seasons, while the D component shows an unusually strong micro-lensing effect with variations of up to ∼10−3 mag d−1 during 2004 and 2005.