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A new emulated Monte Carlo radiative transfer disc-wind model: X-Ray Accretion Disc-wind Emulator – XRADE

Matzeu, G A; Lieu, M; Costa, M T; Reeves, J N; Braito, V; Dadina, M; Nardini, E; Boorman, P G; Parker, M L; Sim, S A; Barret, D; Kammoun, E; Middei, R; Giustini, M; Brusa, M; Cabrera, J Pérez; Marchesi, S

A new emulated Monte Carlo radiative transfer disc-wind model: X-Ray Accretion Disc-wind Emulator – XRADE Thumbnail


G A Matzeu

M T Costa

J N Reeves

V Braito

M Dadina

E Nardini

P G Boorman

M L Parker

S A Sim

D Barret

E Kammoun

R Middei

M Giustini

M Brusa

J Pérez Cabrera

S Marchesi


Abstract We present a new X-Ray Accretion Disk-wind Emulator (xrade) based on the 2.5D Monte Carlo radiative transfer code which provides a physically-motivated, self-consistent treatment of both absorption and emission from a disk-wind by computing the local ionization state and velocity field within the flow. xrade is then implemented through a process that combines X-ray tracing with supervised machine learning. We develop a novel emulation method consisting in training, validating, and testing the simulated disk-wind spectra into a purposely built artificial neural network. The trained emulator can generate a single synthetic spectrum for a particular parameter set in a fraction of a second, in contrast to the few hours required by a standard Monte Carlo radiative transfer pipeline. The emulator does not suffer from interpolation issues with multi-dimensional spaces that are typically faced by traditional X-ray fitting packages such as xspec. xrade will be suitable to a wide number of sources across the black-hole mass, ionizing luminosity, and accretion rate scales. As an example, we demonstrate the applicability of xrade to the physical interpretation of the X-ray spectra of the bright quasar PDS 456, which hosts the best-established accretion-disk wind observed to date. We anticipate that our emulation method will be an indispensable tool for the development of high-resolution theoretical models, with the necessary flexibility to be optimized for the next generation micro-calorimeters on board future missions, like XRISM/Resolve and Athena/X-IFU. This tool can also be implemented across a wide variety of X-ray spectral models and beyond.


Matzeu, G. A., Lieu, M., Costa, M. T., Reeves, J. N., Braito, V., Dadina, M., …Marchesi, S. (2022). A new emulated Monte Carlo radiative transfer disc-wind model: X-Ray Accretion Disc-wind Emulator – XRADE. Monthly Notices of the Royal Astronomical Society, 515(4), 6172-6190.

Journal Article Type Article
Acceptance Date Jul 27, 2022
Online Publication Date Aug 1, 2022
Publication Date 2022-10
Deposit Date Aug 25, 2022
Publicly Available Date Sep 13, 2022
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Peer Reviewed Peer Reviewed
Volume 515
Issue 4
Pages 6172-6190
Keywords Space and Planetary Science; Astronomy and Astrophysics
Public URL
Publisher URL
Additional Information This article has been accepted for publication in Monthly Notices of the Royal Astronomial Society ©: 2022 [The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.


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