A Convolutional Neural Network for the Recovery of Transfer Functions From Velocity-Resolved Reverberation Mapping Data

TL;DR

This paper introduces a novel convolutional neural network approach for deconvolving velocity-delay maps in reverberation mapping data, improving the analysis of the structure around supermassive black holes in active galactic nuclei.

Contribution

The paper presents a new CNN-based method specifically designed for deconvolving velocity-delay maps, addressing challenges posed by noisy and gapped data in reverberation mapping.

Findings

The CNN method successfully reconstructs velocity-delay maps from simulated noisy data.

It outperforms traditional deconvolution techniques in accuracy and robustness.

The approach is adaptable to various reverberation deconvolution problems.

Abstract

One of the hallmarks of active galactic nuclei are that they are highly variable with time. In watching the spectra vary it has been observed that the emission-lines often appear to "reverberate" -- that is they vary in response to continuum variations assumed to originate close to the black hole. This critical observation underlies the reverberation mapping technique, an elegant physics experiment that has allowed us to characterize the environment around many supermassive black holes in nearby active galactic nuclei. Recent observations are of such quality that the response can be measured as a function of velocity across the emission-line, and in doing so we can construct velocity-delay maps that show the structure and physics of the gas in the broad-line region better than any other measurement to date. Unfortunately constructing such maps requires a deconvolution, and given that the data are often noisy and with gaps such deconvolutions are non-trivial. Here we present a novel deconvolution method for the recovery of velocity-delay maps using a custom convolutional neural network architecture, showcasing that such methods have great promise for the deconvolution of reverberation mapping data products. While we have designed this new method with the BLR in mind, in principle this technique could be applied to any reverberation deconvolution problem, including in the accretion disk and torus.