Quasi-Periodic Oscillations of ~ 15 minutes in the Optical Light Curve of the BL Lac S5 0716+714

TL;DR

This study reports the detection of the fastest quasi-periodic oscillation in a blazar's optical light curve, with a 15-minute period, suggesting turbulence behind shocks in the jet.

Contribution

First detection of a 15-minute QPO in a blazar's optical light curve, indicating rapid jet variability at an unprecedented timescale.

Findings

Detected ~15-minute QPO with >3 sigma confidence

QPO is the fastest observed in any blazar at any wavelength

Results suggest turbulence behind shocks in the jet

Abstract

Over the course of three hours on 27 December 2008 we obtained optical (R-band) observations of the blazar S5 0716+714 at a very fast cadence of 10 s. Using several different techniques we find fluctuations with an approximately 15-minute quasi-period to be present in the first portion of that data at a > 3 sigma confidence level. This is the fastest QPO that has been claimed to be observed in any blazar at any wavelength. While this data is insufficient to strongly constrain models for such fluctuations, the presence of such a short timescale when the source is not in a very low state seems to favor the action of turbulence behind a shock in the blazar's relativistic jet.