https://doi.org/10.1140/epjc/s10052-025-15238-y
Regular Article - Theoretical Physics
Searching for synchrotron emission from the geminga TeV halo using the planck satellite
1
Fermi National Accelerator Laboratory, Theoretical Astrophysics Department, 60510, Batavia, IL, USA
2
University of Chicago, Kavli Institute for Cosmological Physics, 60637, Chicago, IL, USA
3
University of Chicago, Department of Astronomy & Astrophysics, 60637, Chicago, IL, USA
a
This email address is being protected from spambots. You need JavaScript enabled to view it.
Received:
4
August
2025
Accepted:
20
December
2025
Published online:
2
February
2026
Pulsars convert a significant fraction of their total spin-down power into very high-energy electrons, leading to the formation of TeV halos. While these halos are well characterized at TeV energies, it remains unclear whether pulsars also accelerate electrons efficiently at lower energies and how these particles propagate through their surrounding environments. We aim to test whether synchrotron emission from 
–
electrons around the Geminga pulsar can be detected in the frequency range observed by the Planck satellite. This would help constrain low-energy particle acceleration and diffusion in the vicinity of pulsars. We model the expected synchrotron emission from Geminga’s TeV halo based on various diffusion and injection spectrum scenarios and compare these predictions to publicly available multi-frequency Planck data. We find no conclusive evidence of spatially extended synchrotron emission associated with Geminga in any of Planck’s frequency bands. Our calculations show that even under favorable diffusion and injection conditions, the predicted synchrotron flux lies well below Planck’s measured background levels.
© The Author(s) 2026
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Funded by SCOAP3.
