I. Flux and color variations of the quadruply imaged quasar HE 0435-1223

TL;DR

This study monitored the flux and color changes of the quadruply imaged quasar HE 0435-1223 over two seasons, revealing intrinsic quasar variability and possible microlensing effects on one component.

Contribution

First detailed multi-epoch photometric monitoring of HE 0435-1223 in VRi bands with independent data reduction techniques.

Findings

Flux decreased by ~0.2-0.4 magnitudes in all components.

Color indices increased significantly, indicating intrinsic variability.

Possible microlensing effects observed on the brightest component.

Abstract

aims: We present VRi photometric observations of the quadruply imaged quasar HE 0435-1223, carried out with the Danish 1.54m telescope at the La Silla Observatory. Our aim was to monitor and study the magnitudes and colors of each lensed component as a function of time. methods: We monitored the object during two seasons (2008 and 2009) in the VRi spectral bands, and reduced the data with two independent techniques: difference imaging and PSF (Point Spread Function) fitting.results: Between these two seasons, our results show an evident decrease in flux by ~0.2-0.4 magnitudes of the four lensed components in the three filters. We also found a significant increase (~0.05-0.015) in their V-R and R-i color indices. conclusions: These flux and color variations are very likely caused by intrinsic variations of the quasar between the observed epochs. Microlensing effects probably also affect the brightest "A" lensed component.