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# Do reverberation mapping analyses provide an accurate picture of the broad line region?

Mangham, S. W., Knigge, C., Williams, P., Horne, Keith, Pancoast, A., Matthews, J. H., Long, K. S., Sim, S. A. and Higginbottom, N. (2019) Do reverberation mapping analyses provide an accurate picture of the broad line region? Monthly Notices of the Royal Astronomical Society.

Record type: Article

## Abstract

Reverberation mapping (RM) is a powerful approach for determining the nature of the broad-line region (BLR) in active galactic nuclei. However, inferring physical BLR properties from an observed spectroscopic time series is a difficult inverse problem. Here, we present a blind test of two widely used RM methods: MEMEcho (developed by Horne) and CARAMEL (developed by Pancoast and collaborators). The test data are simulated spectroscopic time series that track the H$\alpha$ emission line response to an empirical continuum light curve. The underlying BLR model is a rotating, biconical accretion disc wind, and the synthetic spectra are generated via self-consistent ionization and radiative transfer simulations. We generate two mock data sets, representing Seyfert galaxies and QSOs. The Seyfert model produces a largely *negative* response, which neither method can recover. However, both fail $"gracefully"$, neither generating spurious results. For the QSO model both CARAMEL and expert interpretation of MEMEcho's output both capture the broadly annular, rotation-dominated nature of the line-forming region, though MEMEcho analysis overestimates its size by 50%, but CARAMEL is unable to distinguish between additional inflow and outflow components. Despite fitting individual spectra well, the CARAMEL velocity-delay maps and RMS line profiles are strongly inconsistent with the input data. Finally, since the H$\alpha$ line-forming region is rotation dominated, neither method recovers the disc wind nature of the underlying BLR model. Thus considerable care is required when interpreting the results of RM analyses in terms of physical models.

Text
1906.11272v1 - Accepted Manuscript

e-pub ahead of print date: 21 June 2019
Published date: 26 June 2019
Additional Information: 22 pages, 24 figures
Keywords: astro-ph.GA

## Identifiers

Local EPrints ID: 432565
URI: http://eprints.soton.ac.uk/id/eprint/432565
ISSN: 0035-8711
PURE UUID: 4275314c-704c-4506-aac4-37b44c7ba19d
ORCID for S. W. Mangham: orcid.org/0000-0001-7511-5652

## Catalogue record

Date deposited: 18 Jul 2019 16:30

## Contributors

Author: S. W. Mangham
Author: C. Knigge
Author: P. Williams
Author: Keith Horne
Author: A. Pancoast
Author: J. H. Matthews
Author: K. S. Long
Author: S. A. Sim
Author: N. Higginbottom

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