Long-Term Multiwavelength Studies of High-Redshift Blazar 0836+710

TL;DR

This study presents multiwavelength observations of the high-redshift blazar 0836+710 during gamma-ray flares, revealing correlated optical and gamma-ray activity but uncorrelated radio emission, and noting spectral shape changes during different activity states.

Contribution

It provides the first detailed multiwavelength analysis of a high-redshift blazar during gamma-ray flares, highlighting emission region differences and spectral evolution.

Findings

Optical and gamma-ray emissions are correlated with no measurable lag.

Radio emission regions are unrelated to gamma-ray production zones.

Gamma-ray spectrum changes from power law to curved during active states.

Abstract

Aims. The observation of gamma -ray flares from blazar 0836+710 in 2011, following a period of quiescence, offered an opportunity to study correlated activity at different wavelengths for a high-redshift (z=2.218) active galactic nucleus. Methods. Optical and radio monitoring, plus Fermi-LAT gamma-ray monitoring provided 2008-2012 coverage, while Swift offered auxiliary optical, ultraviolet, and X-ray information. Other contemporaneous observations were used to construct a broad-band spectral energy distribution. Results. There is evidence of correlation but not a measurable lag between the optical and gamma-ray flaring emission. On the contrary, there is no clear correlation between radio and gamma-ray activity, indicating radio emission regions that are unrelated to the parts of the jet that produce the gamma-rays. The gamma-ray energy spectrum is unusual in showing a change of shape from a power law to a curved spectrum when going from the quiescent state to the active state.