Results of optical monitoring of 5 SDSS double QSOs with the Nordic Optical Telescope

TL;DR

This study monitored five SDSS double QSOs using the Nordic Optical Telescope, measured time delays, modeled the systems to estimate the Hubble constant, and found no evidence of microlensing variability.

Contribution

First optical R-band light curves and modeling of five SDSS double QSOs, providing new measurements of time delays and estimates of the Hubble constant.

Findings

Measured a 116-day time delay for SDSS J1206+4332.

Estimated Hubble constant as 73 km/s/Mpc and 61.5 km/s/Mpc from different models.

Found no evidence of microlensing variability during monitoring.

Abstract

We present optical R-band light curves of five SDSS double QSOs (SDSS J0903+5028, SDSS J1001+5027, SDSS J1206+4332, SDSS J1353+1138, SDSS J1335+0118) obtained from monitoring at the Nordic Optical Telescope (NOT) between September 2005 and September 2007. We also present analytical and pixelated modeling of the observed systems. For SDSS J1206+4332, we measured the time delay to be 116 days, which, for a Singular Isothermal Ellipsoid model, corresponds to a Hubble constant of 73 km/s/Mpc. Simultaneous pixeleted modeling of five other systems for which a time delay has now been previously measured at the NOT leads to H_0 = 61.5 km/s/Mpc. Finally, by comparing lightcurves of the two images of each system, suitably shifted by the predicted or observed time-delays, we found no evidence for microlensing variability over the course of the monitoring period.