{"about":{"site":"https://codewithpapers.app","non_affiliation":"Code with Papers and Syntology are not affiliated with, endorsed by, or sponsored by Papers with Code, Meta, or the pwc-archive mirror.","licence":"CC BY-SA 4.0","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","attribution":"https://codewithpapers.app/attribution","modified":"archive material modified by Syntology; see the attribution page"},"url":"/paper/shape-and-ionization-of-equatorial-matter","title":"Shape and ionization of equatorial matter near compact objects from X-ray polarization reflection signatures","arxiv_id":"2506.01798","date":"2025-06-02","proceeding":null,"authors":["J. Podgorný"],"abstract":"Motivated by the success of the IXPE mission, we elucidate what can be inferred about 3D matter structures forming about the equatorial plane of accreting compact objects from 0.1-100 keV linear polarization induced by non-relativistic large-scale reflection. We construct a model of an optically thick elevated axially symmetric reflecting medium with arbitrary ionization profile, representing the known diverse scattering environments: from thick winds and super-Eddington funnel structures formed around black holes and neutron stars, to Compton-thick dusty tori of active galactic nuclei and their broad line regions. We assume a central X-ray power-law source with an isotropic, cosine, and slab-corona emission distribution, including intrinsic polarization. The reprocessing is based on constant-density local reflection tables produced with a Monte Carlo method combined with detailed non-LTE radiative transfer, although we also show examples with classical (semi-)analytical reflection prescriptions. We conclude that varying ionization has a similarly strong impact on observed polarization as the observer's inclination and the skew and opening angle of the reflector's inner walls, altogether producing up to tens of % of reflected polarization both parallelly or perpendicularly to the projected axis, depending on the parameter values combination. After testing 3 different ad-hoc shapes of the reflector: a cone, an elliptical torus, and a bowl, we conclude that while in some configurations, their altered curvature produces more than 30% absolute difference in observed total polarization, in others, the adopted shape has a marginal impact. Lastly, we discuss the change of the observed polarization due to relaxing the optically thick assumption on equatorial winds and accreted matter, providing a continuous range of energy-dependent examples between the optically thick and thin scenarios.","url_abs":"https://arxiv.org/abs/2506.01798v1","url_pdf":"https://arxiv.org/pdf/2506.01798v1.pdf","source":{"archive":"pwc-archive (Hugging Face), CC BY-SA 4.0","snapshot":"2025-07-28","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","row_kind":"links_only","authors_date_abstract":"arXiv metadata, CC0 1.0 (https://info.arxiv.org/help/license), from the Kaggle arXiv metadata snapshot of 2026-09-12"},"code_links":[{"paper_slug":"shape-and-ionization-of-equatorial-matter","repo_url":"https://github.com/jpodgorny/torus_integrator","is_official":0,"mentioned_in_paper":0,"mentioned_in_github":1,"framework":"none","reach":null}],"tasks":[],"methods":[],"datasets_introduced":[],"methods_introduced":[],"results":[],"syntology":{"atlas_url":null,"mcp":null,"developers":"https://syntology.ai/developers"},"arxiv_metadata":null,"syntology_extracted_results":null}