| I present studies of neutron stars in various environments. First, I revisit the beat frequency modulated accretion torque model as applied to Z-sources to estimate the equilibrium spin period and magnetic field strength of the neutron star. I examine the argument that scattering clouds may account for the lack of X-ray pulsations, and present observations of QPOs useful for testing cloud models.;I then present observations of the high mass X-ray binary pulsars 4U0115+63 and 4U1907+09. The orbital parameters of 4U0115+63 are derived from a 1994 outburst and the torque-luminosity relationship is measured. Multi-mission measurements of the X-ray absorption and flux of 4U1907+09 are made at all phases of the orbit, including the first measurements of an extended period of low flux. A model of accretion from a spherical wind off a supergiant companion with a trailing stream can fit the primary peak in the average light curve and the absorption column variations, but not the secondary peak. However, the model favors a high inclination angle, suggesting a companion mass similar to a Be-star.;For the bulk of my thesis, I explore the mystery of the unidentified Galactic gamma-ray sources. I present a catalog of 2--10 keV X-ray images made with ASCA of the brightest GeV sources. An excess of moderately bright, hard X-ray sources are found coincident with the GeV source positions. I present evidence for a class of variable gamma-ray sources associated with extended regions of hard X-ray emission, and suggest the variable emission is generated in a synchrotron wind nebula surrounding a fast, young pulsar.;Finally, I present a detailed study of GeV J1417-6100. X-ray and radio mapping reveal two sites of extended non-thermal emission reminiscent of nebulae surrounding young pulsars. These are contained in a region I call the Kookaburra. The brighter source, the Rabbit, has the morphological, spectral, and polarization signatures of a pulsar wind nebula, but no radio point source. The second, fainter source contains a recently discovered high energy radio pulsar consistent with the X-ray nebula peak. Folding the X-ray data results in a possible pulse detection. |
