Population synthesis of Galactic middle-aged pulsar wind nebulae

I. Detection prospects for current and future instruments

¹ Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans s/n, 08193 Barcelona, Spain
² Institut d’Estudis Espacials de Catalunya (IEEC), Gran Capità 2-4, 08034 Barcelona, Spain
³ Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain
⁴ INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze, Italy
⁵ Università degli Studi di Firenze, Via Sansone 1, 50019 Sesto F.no (Firenze), Italy
⁶ INFN – Sezione di Firenze, Via G. Sansone 1, I-50019 Sesto F.no (Firenze), Italy

^★ Corresponding authors: This email address is being protected from spambots. You need JavaScript enabled to view it. ; This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 23 December 2025
Accepted: 14 May 2026

Abstract

Pulsar wind nebulae (PWNe) constitute the largest population of Galactic very high-energy (VHE; E > 100 GeV) γ-ray sources and are key laboratories for studying particle acceleration and pulsar–supernova remnant (SNR) interactions. However, realistic population-level predictions have so far lacked any detailed treatment of the reverberation phase, when the nebula is compressed by the SNR reverse shock, significantly altering its dynamics and radiative spectrum. We employed the hybrid TIDE+L framework, which combines a thin-shell dynamical model with a Lagrangian treatment of the SNR structure during reverberation, allowing for self-consistent evolution of thousands of PWNe across all stages up to 10⁵ yr. Each source was evolved under distributions of pulsar spin-down, SNR, and environmental properties, and the resulting γ-ray fluxes were used to estimate the detectability by current and next-generation γ-ray observatories, while accounting for their sensitivity and sky coverage. The model predicts that the upcoming Cherenkov Telescope Array Observatory (CTAO) will detect an order of magnitude more PWNe than those firmly detected in the tera-electronvolt range, confirming its dominant contribution to the forthcoming tera-electronvolt population census. Our results demonstrate that realistic modeling of reverberation is important for predicting the Galactic tera-electronvolt PWNe population.