A Robust Interpretation of the Fermi Pulsar Phenomenology

The launch of Fermi not only increased the number of gamma-ray pulsars detected, but also doubled the number of observables per pulsar from the magnetic field, B and spin-down power to include the gamma-ray luminosity and spectral cut-off energy. Interestingly, we demonstrate that these four observables are not independent but are related by a relation the describes a 3D plane, i.e., the fundamental plane (FP) of gamma-ray pulsars, embedded in a 4D space. This observed fundamental plane (FP) is remarkably close to the theoretical relation that is obtained, assuming that the pulsar gamma-ray emission is due to curvature radiation. We present advanced kinetic particle-in-cell (PIC) models that reproduce both the shape patterns of the gamma-ray light curves and the FP. Our modeling also provides a detailed description of the death lines of young and millisecond pulsars providing an interpretation of the observed death lines of Fermi young and millisecond gamma-ray pulsars making at the same time predictions regarding the existence of a population of MeV pulsars that are currently undetected. Our results illustrate the expectations for potential future MeV space telescope missions (e.g., AMEGO). Our study provides a comprehensive description of the broad-spectrum Fermi pulsar phenomenology delineating the corresponding underlying microscopic operational regime.