Time Delay Analysis of the Lensed Quasar SDSS J1001+5027

TL;DR

This paper introduces an improved time delay estimation algorithm for strong lens systems, applying it to the quasar SDSS J1001+5027, and demonstrates its effectiveness through simulations and comparison with previous studies.

Contribution

The paper proposes a new 'mirror' estimator and a reliability criteria set, enhancing the accuracy and confidence in time delay measurements for gravitational lens systems.

Findings

The new estimator yields a time delay of approximately -117 days.

Simulations suggest higher data quality reduces uncertainty in estimates.

Results agree with previous studies, validating the method.

Abstract

We modify the algorithm we proposed before in Aghamousa & Shafieloo (2015) on time delay estimation of the strong lens systems incorporating weighted cross-correlation and weighted summation of correlation coefficients. We show the high performance of this algorithm by applying it on Time Delay Challenge (TDC1) simulated data. We apply then our proposed method on the light curves of the lensed quasar SDSS J1001+5027 since this system has been well studied by other groups to compare our results with their findings. In this work we propose a new estimator namely "mirror" estimator along with a list of criteria for reliability test of estimation. Our mirror estimator results to $-117.1^{+7.1}_{-3.7}$ and $-117.1^{+7.2}_{-8.8}$ using simple Monte Carlo simulations and simulated light curves provided by Rathna Kumar et al. (2013) respectively. Although TDC1 simulations do not reflect the properties of SDSS J1001+5027 light curves, using these simulations results to smaller uncertainty which shows the higher quality observations can lead to substantially more precise time delay estimation. Our time delay estimation is in agreement with findings of the other groups for this strong lens system and the difference in the size of the error bars reflects the importance of appropriate light curve simulations.