The all-sky surveys in γ-rays by the imaging Compton telescope (COMPTEL) and the Energetic Gamma Ray Experiment Telescope (EGRET) on board the Compton Gamma Ray Observatory for the first time allows detailed studies of the extragalactic diffuse emission at γ-ray energies greater 1 MeV. A preliminary analysis of COMPTEL data indicates a significant decrease in the level of the derived cosmic dif...

The X-ray emission from most accreting white dwarfs (WDs) in symbiotic binary stars is quite soft. Several symbiotic WDs, however, produce strong X-ray emission at energies greater than ∼ 20 keV. The Swift BAT instrument has detected hard X-ray emission from 4 such accreting WDs in symbiotic stars: RT Cru, T CrB, CD −57 3057, and CH Cyg. In one case (RT Cru), Swift detected X-rays out to greate...

  Solitary pulmonary nodule (SPN) is a frequent finding on the chest x-ray and computed tomography. Nuclear medicine techniques play an important role in the diagnosis and management of SPN. In the current review, we briefly will explain the different nuclear medicine modalities in this regard including positron emission tomography (PET) using 18-F-FDG, and 11-C-Methionine, and single photon em...

We discuss the origin of superluminal radio jets in Black hole X-ray binaries with relativistic radio jets in our Galaxy popularly known as microquasars. We classify the relativistic superluminal jet according to the radio emission in black hole X-ray binaries (transient or persistent) rather than the mass of the companion. The black hole X-ray binaries with transient radio emission (mostly LMX...

X-ray emission traces the gaseous environments of radio sources. The medium must be present for jet confinement, but what are its influence on jet fuelling, dynamics, propagation, and disruption? The observational situation is both complicated and enriched by radio sources being multi-component X-ray emitters, with several possible regions of non-thermal emission. Recent work, primarily based o...

The afterglows of gamma-ray bursts (GRBs) have commonly been assumed to be due to shocks sweeping up the circum-stellar medium. However, most GRBs have been found in dense star-forming regions where a significant fraction of the prompt X-ray emission can be scattered by dust grains. Here we revisit the behavior of dust scattering of X-rays in GRBs. We find that the features of some X-ray afterg...

We report Chandra X-ray Observatory and 1.4 GHz Australian Long Baseline Array (LBA) observations of the radio galaxy PKS 2153–69 and its environment. The Chandra image reveals a roughly spherical halo of hot gas extending out to 30 kpc around PKS 2153–69. Two depressions in the surface brightness of the X-ray halo correspond to the large scale radio lobes, and interpreting these as cavities in...

Vela X is a pulsar wind nebula (PWN) associated with the active pulsar B0833-45 and contained within the Vela supernova remnant (SNR). A collimated X-ray filament (“cocoon”) extends south-southwest from the pulsar to the center of Vela X. VLA observations uncovered radio emission coincident with the eastern edge of the cocoon and H.E.S.S. has detected TeV γ-ray emission from this region as well...

The X-ray emission from the faintest X-ray elliptical and S0 galaxies is characterized by a hard ∼5 keV component, and a very soft ∼0.2 keV component. The hard component has generally been regarded as the integrated emission from low mass X-ray binaries (LMXBs), but the origin of the soft component is unknown. We present evidence which suggests that LMXBs also exhibit a soft component, which is...

Analyses of the X-ray data of the five young shell-type supernova remnants Cas A, Kepler, Tycho, SN 1006, and RCW 86 suggest that some of the X-ray emission of these sources is non-thermal. This non-thermal emission is qualitatively consistent with models of the broad-band (radio-to-X-ray) synchrotron spectra of remnants and does not seem to be consistent with other non-thermal X-ray emission p...