| Issue |
A&A
Volume 705, January 2026
|
|
|---|---|---|
| Article Number | L4 | |
| Number of page(s) | 6 | |
| Section | Letters to the Editor | |
| DOI | https://doi.org/10.1051/0004-6361/202557202 | |
| Published online | 08 January 2026 | |
Letter to the Editor
Microquasar remnants as hidden PeVatrons
1
Instituto Argentino de Radioastronomía (CCT La Plata, CONICET; CICPBA; UNLP), C.C.5, (1894), Villa Elisa, Argentina
2
Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, B1900FWA La Plata, Argentina
3
Departament de Física Quàntica i Astrofísica, Institut de Ciències del Cosmos (ICC), Universitat de Barcelona (IEEC-UB), Martí i Franquès 1, E08028 Barcelona, Spain
⋆ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.
Received:
11
September
2025
Accepted:
8
December
2025
The Large High Altitude Air Shower Observatory (LHAASO) has revealed numerous ultrahigh-energy gamma-ray sources of unknown origin. We propose that a fraction of them can be explained by microquasar remnants, i.e., binary systems where mass transfer has ceased and the central engine is quenched. Cosmic rays injected during the active phase of a microquasar may remain confined within its cocoon and subsequently interact with nearby molecular clouds, producing bright gamma-ray emission through pp collisions. Remnants of former super-Eddington systems can act as dark PeVatrons, releasing particles up to ∼10 PeV that illuminate surrounding clouds producing gamma rays reaching hundreds of tera-electron volts. This scenario provides a natural explanation for several unidentified Galactic LHAASO sources.
Key words: acceleration of particles / radiation mechanisms: non-thermal / relativistic processes
© The Authors 2026
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
This article is published in open access under the Subscribe to Open model. This email address is being protected from spambots. You need JavaScript enabled to view it. to support open access publication.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.