Unlocking the radio-gamma spectrum of the pulsar wind nebula around PSR J1124-5916 in SNR G292.0+1.8

TL;DR

This paper reports the first detection of GeV gamma-ray emission from the pulsar wind nebula in SNR G292.0+1.8, providing new insights into its emission mechanisms and magnetic environment through detailed spectral analysis.

Contribution

It presents the first spectral resolution of the pulsar and PWN contributions at high energies in G292.0+1.8, and constrains the broadband SED with a detailed model of particle acceleration and cooling.

Findings

Detection of unpulsed GeV gamma-ray emission from the PWN.

The nebula's emission is modeled with a single electron population with two spectral breaks.

The inferred magnetic field is about 15 microGauss, similar to 3C 58.

Abstract

We present the first detection of GeV $\gamma$-ray emission potentially associated with the pulsar wind nebula (PWN) hosted by the young core-collapse supernova remnant G292.0+1.8, based on a detailed time-resolved analysis of \textit{Fermi}-LAT data. By isolating the unpulsed component from the dominant magnetospheric radiation of PSR~J1124$-$5916, we successfully disentangle a candidate nebular emission in the GeV range, characterise its morphology and extract its spectrum. This identification places G292.0+1.8 among the few systems in which the pulsar and PWN contributions have been spectrally resolved at high energies, offering new insight into their respective emission mechanisms. We characterise the $\gamma$-ray spectrum of the pulsar and model the broadband spectral energy distribution (SED) of the PWN using radio, X-ray, and GeV data. The emission is well described by a single electron population with two spectral breaks: one intrinsic to the injection spectrum and another produced by synchrotron cooling in a magnetic field of $\sim$15~$\mu$G. Notably, the inferred magnetic field and the low TeV flux of the nebula resemble those of 3C~58, suggesting that similar low-field environments can arise in young PWNe. The high-energy portion of the SED is now tightly constrained by our GeV detection and existing TeV upper limits. Compared to our model, earlier predictions tend to underpredict the $\gamma$-ray flux, while others that succeed in reproducing the GeV component often overpredict the TeV emission. This mismatch underscores the challenges in modelling particle acceleration and radiation processes in young PWNe and establishes G292.0+1.8 as a valuable benchmark for testing and refining such models.