Time delay of SBS 0909+532

Ullán, A.; Goicoechea, L. J.; Zheleznyak, A. P.; Koptelova, E.; Bruevich, V. V.; Akhunov, T.; Burkhonov, O.

doi:10.1051/0004-6361:20054283

Cited by 26 publications

(27 citation statements)

References 46 publications

(77 reference statements)

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“…of Ullán et al (2006). The NMF method, when applied to the entire light curve, gives a delay Δt BA ∼ 47 days, as displayed in Fig.…”

Section: Application To 11 Lensed Quasarsmentioning

confidence: 92%

Time delays for eleven gravitationally lensed quasars revisited

Eulaers

Magain

2011

A&A

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Aims. We test the robustness of published time delays for 11 lensed quasars by using two techniques to measure time shifts in their light curves. Methods. We chose to use two fundamentally different techniques to determine time delays in gravitationally lensed quasars: a method based on fitting a numerical model and another one derived from the minimum dispersion method introduced by Pelt and collaborators. To analyse our sample in a homogeneous way and avoid bias caused by the choice of the method used, we apply both methods to 11 different lensed systems for which delays have been published: JVAS B0218+357, SBS 0909+523, RX J0911+0551, FBQS J0951+2635, HE 1104-1805, PG 1115+080, JVAS B1422+231, SBS 1520+530, CLASS B1600+434, CLASS B1608+656, and HE 2149-2745 Results. Time delays for three double lenses, JVAS B0218+357, HE 1104-1805, and CLASS B1600+434, as well as the quadruply lensed quasar CLASS B1608+656 are confirmed within the error bars. We correct the delay for SBS 1520+530. For PG 1115+080 and RX J0911+0551, the existence of a second solution on top of the published delay is revealed. The time delays in four systems, SBS 0909+523, FBQS J0951+2635, JVAS B1422+231, and HE 2149-2745 prove to be less reliable than previously claimed. Conclusions. If we wish to derive an estimate of H 0 based on time delays in gravitationally lensed quasars, we need to obtain more robust light curves for most of these systems in order to achieve a higher accuracy and robustness on the time delays.

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“…of Ullán et al (2006). The NMF method, when applied to the entire light curve, gives a delay Δt BA ∼ 47 days, as displayed in Fig.…”

Section: Application To 11 Lensed Quasarsmentioning

confidence: 92%

Time delays for eleven gravitationally lensed quasars revisited

Eulaers

Magain

2011

A&A

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“…A wide variety of algorithms have been developed for the determination of time delays in gravitational lens systems. The methods presented here are based on the chi-squared χ 2 (Gaynullina et al 2005;Ullán et al 2006) and dispersion D 2 (Pelt et al 1996) minimizations. In general, all the techniques proceed in a similar way -they try to find how to match at best two given light curves.…”

Section: T I M E D E L Ay C a L C U L At I O N Smentioning

confidence: 99%

Adaptive PSF fitting – a highly performing photometric method and light curves of the GLS H1413+117: time delays and micro-lensing effects

Akhunov

Wertz

Elyiv

et al. 2016

Mon. Not. R. Astron. Soc.

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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 χ 2 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: t AB = −17.4 ± 2.1, t AC = −18.9 ± 2.8 and t AD = 28.8 ± 0.7 d using the χ 2 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 z l = 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,

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“…We used a χ 2 minimization to find the flux ratio for each segment. In general, the shifted epochs of A do not coincide with the epochs of B, therefore we introduce bins in A around the epochs of B (e.g., Ullán et al 2006). These bins have a semisize α of 6 or 9 d. In Table 3 we give the best solutions and their reduced chi-square values, as well as some 2σ intervals for B/A.…”

Section: Two-colour Flux Ratio Over the 2000-2010 Decadementioning

confidence: 99%

A 5.5-year robotic optical monitoring of Q0957+561: substructure in a non-local cD galaxy

Shalyapin

Goicoechea

Gil-Merino

2012

A&A

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New light curves of the gravitationally lensed double quasar Q0957+561 in the gr bands during 2008-2010 include densely sampled, sharp intrinsic fluctuations with unprecedentedly high signal-to-noise ratio. These relatively violent flux variations allow us to very accurately measure the g-band and r-band time delays between the two quasar images A and B. Using correlation functions, we obtain that the two time delays are inconsistent with each other at the 2σ level, with the r-band delay exceeding the 417-day delay in the g band by about 3 days. We also studied the long-term evolution of the delay-corrected flux ratio B/A from our homogeneous two-band monitoring with the Liverpool Robotic Telescope between 2005 and 2010. This ratio B/A slightly increases in periods of violent activity, which seems to be correlated with the flux level in these periods. The presence of the previously reported dense cloud within the cD lensing galaxy, along the line of sight to the A image, could account for the observed time delay and flux ratio anomalies.

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Time delay of SBS 0909+532

Cited by 26 publications

References 46 publications

Time delays for eleven gravitationally lensed quasars revisited

Time delays for eleven gravitationally lensed quasars revisited

Adaptive PSF fitting – a highly performing photometric method and light curves of the GLS H1413+117: time delays and micro-lensing effects

A 5.5-year robotic optical monitoring of Q0957+561: substructure in a non-local cD galaxy

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