Reverberation in the UV-Optical Continuum Brightness Fluctuations of MACHO Quasar 13.5962.237

TL;DR

This study analyzes UV-Optical brightness fluctuations in a quasar, revealing reverberation patterns and semi-periodic behavior that could aid quasar detection through photometric monitoring.

Contribution

It provides the first detailed evidence of reverberation patterns in quasar brightness fluctuations using long-term optical data.

Findings

Reverberation patterns follow initial brightness disturbances.

Pulse amplitudes are around 12% with 80-day widths.

A semi-periodic pattern of approximately 2 years is observed.

Abstract

We examine the nature of brightness fluctuations in the UV-Optical spectral region of an ordinary quasar with 881 optical brightness measurements made during the epoch 1993 - 1999. We find evidence for systematic trends having the character of a pattern of reverberations following an initial disturbance. The initial pulses have brightness increases of order 20% and pulse widths of 50 days, and the reverberations have typical amplitudes of 12% with longer mean pulse widths of order 80 days and pulse separations of order 90 days. The repeat pattern occurs over the same time scales whether the initial disturbance is a brightening or fading. The lags of the pulse trains are comparable to the lags seen previously in reverberation of the broad blue-shifted emission lines following brightness disturbances in Seyfert galaxies, when allowance is made for the mass of the central object. In addition to the burst pulse trains, we find evidence for a semi-periodicity with a time scale of 2 years. These strong patterns of brightness fluctuations suggest a method of discovering quasars from photometric monitoring alone, with data of the quality expected from large brightness monitoring programs like Pann-Stars and LSST.