2025ApJ...988..200L

We present results of more than 13 yr of Fermi-Large Area Telescope (LAT) data analysis for the Vela pulsar from 60 MeV to 100 GeV and its pulsar wind nebula (PWN), Vela X, for E > 1 GeV in the off-pulse phases. We find that the Vela X PWN can be best characterized using two extended components: a large radial Gaussian accompanied by an offset, compact radial disk, both with a similar spectral index, Γ ∼ 2.3. The common spectral properties support a common PWN origin, but a supernova remnant component is plausible for the compact radial disk. With an updated Vela X model, the phase-resolved spectral properties of the Vela pulsar are explored through a phase-resolved analysis. The phase-resolved spectral properties of the pulsar, such as the spectral energy distribution (SED) peak energy E_p, the width of the SED at its peak d_p, and the asymptotic (low-energy) spectral index Γ₀, are presented. The best-fit spectral models for each LAT pulse peak (Peak 1 and Peak 2) are extrapolated to UV energies and compared to archival, phase-resolved spectra at UV, X-ray, soft γ-ray, and TeV energies. We also discuss the physical implications of our modeling and the data comparisons.