New near-infrared observations and lens-model constraints for UM673^⋆,⋆⋆

¹ Department of PhysicsNational Taiwan University, No.1, Sec. 4, Roosevelt Rd., 106 Taipei, Taiwan
e-mail: ekaterina@phys.ntu.edu.tw; chiuehth@phys.ntu.edu.tw
² Graduate Institute of Astronomy, National Central University, Jhongli City, Taoyuan County 320, Taiwan
e-mail: wchen@astro.ncu.edu.tw
³ Sternberg Astronomical Institute (SAI), Moscow M.V. Lomonosov State University, Universitetskii pr. 13, 119992 Moscow, Russia

Received: 8 July 2013
Accepted: 1 April 2014

Abstract

Aims. We performed a detailed photometric analysis of the lensed system UM673 (Q0142-100) and an analysis of the tentative lens models.

Methods. High-resolution adaptive optics images of UM673 taken with the Subaru telescope in the H band were examined. We also analysed the J, H and K-band observational data of UM673 obtained with the 1.3 m telescope at the CTIO observatory.

Results. We present photometry of quasar components A and B of UM673, the lens, and the nearby bright galaxy using H-band observational data obtained with the Subaru telescope. Based on the CTIO observations of UM673, we also present J- and H-band photometry and estimates of the J, H and K-band flux ratios between the two UM673 components in recent epochs. The near-infrared fluxes of the A and B components of UM673 and their published optical fluxes are analysed to measure extinction properties of the lensing galaxy. We estimate the extinction-corrected flux ratio between components A and B to be about 2.14 mag. We discuss lens models for the UM673 system constrained with the positions of the UM673 components, their flux ratio, and the previously measured time delay.