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

Abstract

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.

Citation

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. P., & 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. https://doi.org/10.1093/mnras/stac2155

• 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
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 515
• Issue: 4
• Pages: 6172-6190
• DOI: https://doi.org/10.1093/mnras/stac2155
• Keywords: Space and Planetary Science; Astronomy and Astrophysics
• Public URL: https://nottingham-repository.worktribe.com/output/10072007
• Publisher URL: https://academic.oup.com/mnras/article/515/4/6172/6653103
• 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.