Pulsar Wind Nebula Studies in the Gamma-ray Era with the Fermi-LAT

There are at least 125 Galactic pulsar wind nebulae (PWNe) that have been discovered from radio wavelengths to TeV gamma-rays, the majority of which were first identified in radio or X-ray surveys. Now, gamma-rays may become key to finding and characterizing PWNe. In fact, the majority of identified Galactic TeV sources detected by Imaging Air Cherenkov Telescopes are classified as PWNe. The high-energy emission from these sources indicates they may be responsible for producing the bulk of leptonic Galactic cosmic rays (CRs). Combining available MeV-GeV data with observations in the TeV band is therefore critical for precise characterization of high-energy emission from the relativistic particle population in PWNe, thus revealing the capability to produce a significant fraction of the detected Galactic CR flux. However, the Fermi-LAT has only identified a small fraction of MeV-GeV PWN counterparts, limited by the PWNe largely being located along the Galactic plane, embedded within bright diffuse gamma-ray emission. Bright GeV emission from a central pulsar can also obscure PWNe. A systematic search in the 11.5yr Fermi-LAT dataset is presented. The locations of PWNe identified in other wavelengths are targeted, omitting systems that have pulsars detected by the Fermi-LAT. We present the preliminary results for the Fermi-LAT analysis of 58 regions accompanied by the broadband analyses of two newly detected Fermi PWNe and the physical implications of the results.