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

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., …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.