Work

Blueshifted lines from the inner accretion disc's rotation can explain quasar absorption "forests''

Year: 2026

Type: preprint

Abstract: Recent XRISM observations of active galactic nuclei such as PDS 456 have revealed ``forests'' of absorption lines best modeled by five distinct absorption zones with varying large blueshifts. We propose a model in which these relativistic blueshifts originate from the motion of the accretion disc itself, rather than from a clumpy super-Eddington outflow at hundreds of gravitational radii $r_g\equiv GM/c^2$. We demonstrate that thin rings of absorbing material lying just above the accretion disc at varying radii can produce the observed energy shifts and separations of the absorption zones. In this model, the PDS 456 transmission spectrum is well reproduced by rings with widths $Δr\lesssim1r_g$ at locations between the black hole's innermost stable circular orbit (ISCO) and $\approx15r_g$. This model suggests that the absorption forests seen in XRISM observations can probe the surface structure of the innermost ($\lesssim15r_g$) regions of quasar accretion discs.

Source: arXiv (Cornell University)

DOI: 10.48550/arxiv.2604.09433

Authors: Hankla, Amelia M., Baker, Fergus J. E., Wilkins, Daniel R., Fabian, Andrew C.

Institutions: University of Maryland, College Park, The Ohio State University, University of Cambridge

Language: English

Topic: Astrophysical Phenomena and Observations

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: green

Funders: National Aeronautics and Space Administration, Space Telescope Science Institute, European Commission

Awards: G285095251, G433322167, G58316358, G6273510985

OpenAlex ID: W7154106976

Cites: 2

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Related to: 10