PSR J0437-4715 is a millisecond pulsar (MSP) thought to be “pair formation starved” (having limited pair cascades due to magnetic photon absorption). Fortunately the general relativistic (GR) electrodynamical model under consideration applicable to this pulsar have few free parameters. We model PSR J0437-4715’s visibility [1], using a 3D model which incorporates the variation of the GR E-field ...

Gamma-ray lines from radioactive isotopes, ejected into interstellar space by cosmic nucleosynthesis events, are observed with new space telescopes. The Compton Observatory had provided a sky survey for the isotopes 26 Al, detecting supernova radioactivity and the diffuse glow of long-lived radioactivity from massive stars in the Galaxy. High-resolution spectroscopy is now being exploited with ...

Gamma-ray bursts (GRBs) are bright flashes of gamma rays coming from the cosmos. They occur roughly once per day, typically last for tens of seconds, and are the most luminous events in the universe. More than three decades after their discovery, and after pioneering advances from space and ground experiments, they still remain mysterious. The launch of the Swift and Fermi satellites in 2004 an...

Extended, fading emissions in multi-wavelength are observed following Gamma-ray bursts (GRBs). Recent broadband observational campaigns led by the Swift Observatory reveal rich features of these GRB afterglows. Here we review the latest observational progress and discuss the theoretical implications for understanding the central engine, composition, and geometric configuration of GRB jets, as w...

This paper summarizes recents results in γ-ray astronomy, most of which were derived with data from groundbased γ-ray detectors. Many of the contributions presented at this conference involve multiwavelength studies which combine ground-based γ-ray measurements with optical data or space-based X-ray and γ-ray measurements. Besides measurements of the diffuse emission from the Galaxy, observatio...

I consider various possibilities for making gamma-ray bursts, particularly from close binaries. In addition to the much-studied neutron star+neutron star and black hole+neutron star cases usually considered good candidates for short-duration bursts, there are also other possibilities. In particular, neutron star+massive white dwarf has several desirable features. These systems are likely to pro...

Using observations from an extensive monitoring campaign with the Hubble Space Telescope we present the detection of an intermediate time flux excess which is redder in color relative to the afterglow of GRB 011121, currently distinguished as the gamma-ray burst with the lowest known redshift. The red “bump,” which exhibits a spectral roll-over at ∼7200 Å, is well described by a redshifted Type...

It is proposed that the gamma-ray photons that characterize the prompt emission of gamma-ray bursts are produced through the Compton-drag process, which is caused by the interaction of a relativistic fireball with a very dense soft photon bath. If gamma-ray bursts are indeed associated with supernovae, then the exploding star can provide enough soft photons for radiative drag to be effective. T...

High energy gamma-ray emission has been observed above 100 MeV from at least 40 active galactic nuclei (AGN) by the EGRET instrument on the Compton Gamma Ray Observatory (CGRO), and above 300 GeV gamma rays have been detected by the Whipple observatory from two AGN. The sources detected so far are \blazars" indicating a jet origin for the gamma rays. They are seen to be variable on time scales ...

Gamma-ray burst populations