Related papers: Radio detections towards unidentified variable EGR…
Ultra-high-energy (E$>$100 Tev) Extensive Air Showers (EASs) have been monitored for a period of five years (1997 - 2003), using a small array of scintillator detectors in Tehran, Iran. The data have been analyzed to take in to account of…
Among unidentified gamma-ray sources in the galactic plane, there are some that present significant variability and have been proposed to be high-mass microquasars. To deepen the study of the possible association between variable low…
We present results from a radio survey for variable and transient sources on 15-min timescales, using the Australian SKA Pathfinder (ASKAP) pilot surveys. The pilot surveys consist of 505 h of observations conducted at around 1 GHz…
Despite the plethora of deep (sub-mJy) radio surveys there remains considerable doubt as to the exact nature of the galaxies contributing to the source counts. Current evidence suggests that starformation in moderately luminous 'normal'…
We examine the radio properties of EGRET-detected blazars observed as part of the VLBA Imaging and Polarimetry Survey (VIPS). VIPS has a flux limit roughly an order of magnitude below the MOJAVE survey and most other samples that have been…
We investigate the radio and gamma-ray beaming properties of normal and millisecond pulsars by selecting two samples from the known populations. The first, Sample G, contains pulsars which are detectable in blind searches of gamma-ray data…
We present a study of the unidentified gamma-ray source 3EG J0542+2610. This source is spatially superposed to the supernova remnant G180.0-1.7, but its time variability makes unlikely a physical link. We have searched into the EGRET…
We present a search for transient and highly variable sources at low radio frequencies (150-200 MHz) that explores long timescales of 1-3 years. We conducted this search by comparing the TIFR GMRT Sky Survey Alternative Data Release 1 (TGSS…
Measurements of the diffuse extragalactic gamma-ray background (EGRB) are complicated by a strong Galactic foreground. Estimates of the EGRB flux and spectrum, obtained by modeling the Galactic emission, have produced a variety of…
Compact, steep-spectrum radio sources are key tracers of exotic astrophysical objects such as pulsars and high-redshift radio galaxies. All-sky radio surveys at different frequencies, like the TIFR-GMRT Sky Survey (TGSS) and the NRAO VLA…
We study the $\gamma$-ray emission from the pulsar magnetosphere based on outer gap models, and the TeV radiation from pulsar wind nebulae (PWNe) through inverse Compton scattering using a one-zone model. We showed previously that GeV…
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…
We discuss the ability of the GLAST Large Area Telescope (LAT) to identify, resolve, and study the high energy gamma-ray sky. Compared to previous instruments the telescope will have greatly improved sensitivity and ability to localize…
Radio observations of very high energy (VHE) gamma-ray sources are fundamental to identify and reveal their nature, as well as to understand the physics behind these energetic sources. I will comment on some characteristics of extragalactic…
We present the preliminary results from two new surveys of blazars that have direct implications on the GLAST detection of extragalactic sources from two different perspectives: microwave selection and a combined deep X-ray/radio selection.…
The origin of the diffuse extragalactic, high-energy gamma-ray background (EGRB) filling the Universe remains unknown. The spectrum of this extragalactic radiation, as measured by the EGRET on-board CGRO, is well-fit by a power law across…
We present results of Compton Gamma-Ray Observatory EGRET observations of the unidentified high-energy gamma-ray sources 2EG J1049-5847 (GEV J1047-5840, 3EG J1048-5840) and 2EG J1103-6106 (3EG J1102-6103). These sources are spatially…
One way to understand the nonthermal history of the universe is by establishing the origins of the unresolved and truly diffuse extragalactic gamma rays. Dim blazars and radio/gamma galaxies certainly make an important contribution to the…
In order to determine the location of the gamma-ray emission site in blazars, we investigate the time-domain relationship between their radio and gamma-ray emission. Light-curves for the brightest detected blazars from the first 3 years of…
The 100-m Robert C. Byrd Green Bank Telescope (GBT) and the Owens Valley Radio Observatory (OVRO) 40-m radio telescope have been used to conduct a survey of 3165 known extragalactic radio sources over 143 square degrees of the sky. Target…