Sub-luminous gamma-Ray pulsars
  Most pulsars observed by the Fermi LAT have gamma-ray luminosities scaling with spindown power Edot as L_gamma (Edot x 10^33 erg/s)^{1/2}. However, there exist one detection and several upper limits an order of magnitude or more fainter than this trend. We describe these `sub-luminous' gamma-ray pulsars, and discuss the case for this being an orientation effect. Of the 12 known young radio pulsars with Edot>10^34 erg/s and d<2kpc several are substantially sub-luminous. The limited available geometrical constraints favor aligned geometries for these pulsars, although no one case for alignment is compelling. In this scenario GeV emission detected from such sub-luminous pulsars can be due to a lower altitude, lower-power accelerator gap. 
R. W. Romani, M. Kerr, H. A. Craig, S. Johnston, I. Cognard and D. A.   Smith
astro-ph.HE