Skip to main content

Research Repository

Advanced Search

A Complex Dust Morphology in the High-luminosity AGN Mrk 876

Landt, Hermine; Mitchell, Jake A.J.; Ward, Martin J.; Mercatoris, Paul; Pott, Jörg-Uwe; Horne, Keith; Hernández Santisteban, Juan V.; Malhotra, Daksh; Cackett, Edward M.; Goad, Michael R.; Romero Colmenero, Encarni; Winkler, Hartmut

A Complex Dust Morphology in the High-luminosity AGN Mrk 876 Thumbnail


Paul Mercatoris

Jörg-Uwe Pott

Keith Horne

Juan V. Hernández Santisteban

Daksh Malhotra

Edward M. Cackett

Michael R. Goad

Encarni Romero Colmenero

Hartmut Winkler


Recent models for the inner structures of active galactic nuclei (AGNs) advocate the presence of a radiatively accelerated dusty outflow launched from the outer regions of the accretion disk. Here, we present the first near-IR variable (rms) spectrum for the high-luminosity nearby AGN Mrk 876. We find that it tracks the accretion disk spectrum out to longer wavelengths than the mean spectrum, due to a reduced dust emission. The implied outer accretion disk radius is consistent with the IR results predicted by a contemporaneous optical accretion disk reverberation mapping campaign, and much larger than the self-gravity radius. The reduced flux variability of the hot dust could either be due to the presence of a secondary constant dust component in the mean spectrum or be introduced by the destructive superposition of the dust and accretion disk variability signals, or be some combination of the two. Assuming thermal equilibrium for optically thin dust, we derive the luminosity-based dust radii for different grain properties, using our measurement of the temperature. We find that in all the cases considered, the values are significantly larger than the dust response time measured by IR photometric monitoring campaigns, with the least discrepancy present relative to the result for a wavelength-independent dust emissivity law, i.e., a blackbody, which is appropriate for large grain sizes. This result can be well explained by assuming a flared disk-like structure for the hot dust.


Landt, H., Mitchell, J. A., Ward, M. J., Mercatoris, P., Pott, J., Horne, K., …Winkler, H. (2023). A Complex Dust Morphology in the High-luminosity AGN Mrk 876. Astrophysical Journal, 945(1), Article 62.

Journal Article Type Article
Acceptance Date Feb 2, 2023
Online Publication Date Mar 7, 2023
Publication Date Mar 1, 2023
Deposit Date Apr 28, 2023
Publicly Available Date Apr 28, 2023
Journal Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 945
Issue 1
Article Number 62
Public URL


Published Journal Article (1.3 Mb)

Publisher Licence URL

Copyright Statement
Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

You might also like

Downloadable Citations