Speaker
Description
We present a reanalysis of the \textit{Fermi}-LAT data of V1674 Her, a rapidly rotating intermediate polar with GeV $\gamma$-ray emission first detected during its 2021 nova outburst. Previous interpretations of the $\gamma$-ray emission from V1674 Her have primarily invoked particle acceleration in shocks associated with the nova ejecta. Here, we investigate the temporal and spectral properties of the $\gamma$-ray emission and explore magnetic reconnection as an alternative particle-acceleration mechanism. We perform a deep periodicity search of the \textit{Fermi}-LAT data at both the white-dwarf spin period and the binary orbital period to investigate possible modulation of the $\gamma$-ray emission by the characteristic timescales of the system. In addition, using the $\gamma$-ray activity observed during the 2021 nova outburst as a reference, we conduct a systematic search for similar transient enhancements throughout the full \textit{Fermi}-LAT data set. Several candidate episodes of enhanced $\gamma$-ray emission are identified, although at lower statistical significance than the 2021 event, suggesting that V1674 Her may exhibit recurrent episodes of high-energy activity. We further perform broadband spectral analysis using Power-Law, Log-Parabola, and PLSuperExpCutoff2 models. Among the models considered, the Log-Parabola provides the preferred description of the $\gamma$-ray spectrum, indicating spectral curvature that is not adequately described by a simple Power-Law model. The combination of spectral curvature and recurrent transient activity provides additional constraints on the physical origin of the $\gamma$-ray emission. We interpret these results within a magnetic-reconnection framework in which interactions between the magnetic field of the rapidly rotating white dwarf and the surrounding accretion flow can trigger reconnection and generate strong electric fields capable of accelerating particles to relativistic energies. The resulting non-thermal particles can produce GeV $\gamma$-rays through hadronic channels. We investigate whether this mechanism can reproduce the observed spectral shape and account for the recurrent episodes of enhanced $\gamma$-ray activity in V1674 Her. This provides a physically motivated alternative to shock-driven particle acceleration and offers a framework for understanding high-energy emission from intermediate polars.