Color Variability of the Blazar AO 0235+16

TL;DR

This study analyzes multicolor observations of the blazar AO 0235+16, revealing that its spectral energy distribution remains constant within specific intervals but varies across them, supporting a synchrotron emission model.

Contribution

It provides a detailed analysis of the color variability and spectral energy distribution of AO 0235+16, demonstrating the synchrotron nature of its variable component across multiple wavelengths.

Findings

Spectral energy distribution remains constant within intervals

SED varies strongly between intervals

Supports synchrotron emission as the origin of variability

Abstract

Multicolor (UBVRIJHK) observations of the blazar AO 0235+16 are analyzed. The light curves were compiled at the Turin Observatory from literature data and the results of observations obtained in the framework of the WEBT program (http://www.to.astro/blazars/webt/). The color variability of the blazar was studied in eight time intervals with a sufficient number of multicolor optical observations; JHK data are available for only one of these. The spectral energy distribution (SED) of the variable component remained constant within each interval, but varied strongly from one interval to another. After correction for dust absorption, the SED can be represented by a power law in all cases, providing evidence for a synchrotron nature of the variable component. We show that the variability at both optical and IR wavelengths is associated with the same variable source.