Related papers: Wind-induced Natural Gamma Radiation
In this letter we suggest a scenario for simultaneous emission of gravitational-wave and $\gamma$-ray bursts (GRBs) from soft gamma-ray repeaters (SGRs). we argue that both of the radiations can be generated by a super-Eddington accreting…
We observed the periodic radio transient GLEAM-X J162759.5-523504.3 (GLEAM-X J1627) using the Chandra X-ray Observatory for about 30-ks on January 22-23, 2022, simultaneously with radio observations from MWA, MeerKAT and ATCA. Its radio…
It is likely that one or more gamma-ray bursts within our galaxy have strongly irradiated the Earth in the last Gy. This produces significant atmospheric ionization and dissociation, resulting in ozone depletion and DNA-damaging ultraviolet…
We describe results of modeling the effects on Earth-like planets of long-duration gamma-ray bursts (GRBs) within a few kiloparsecs. A primary effect is generation of nitrogen oxide compounds which deplete ozone. Ozone depletion leads to an…
We predict the observational signatures of galaxy scale outflows powered by active galactic nuclei (AGN). Most of the emission is produced by the forward shock driven into the ambient interstellar medium (ISM) rather than by the reverse…
The X-ray mission Chandra has observed a dramatic X-ray flare -- a brightening by a factor of 50 for only three hours -- from Sgr A*, the Galactic Center supermassive black hole. Sgr A* has never shown variability of this amplitude in the…
As one of the brightest active blazars in both X-ray and very high energy $\gamma$-ray bands, Mrk 501 is very useful for physics associated with jets from AGNs. The ARGO-YBJ experiment is monitoring it for $\gamma$-rays above 0.3 TeV since…
Gamma-ray loud X-ray binaries are binary systems that show non-thermal broadband emission from radio to gamma rays. If the system comprises a massive star and a young non-accreting pulsar, their winds will collide producing broadband…
The knowledge of the rate of soft gamma-ray repeater (SGR) giant flares is important for understanding the giant flare mechanism and the SGR energy budget in the framework of the magnetar model. We estimate the upper limit to the rate using…
Afterglows of gamma-ray bursts often show flares, plateaus, and sudden intensity drops: these temporal features are difficult to explain as coming from the forward shock. We calculate radiative properties of early GRB afterglows with the…
During intense geomagnetic storms, the rapid and significant production of NO followed by its associated infrared radiative emission in lower thermosphere contributes crucially to the energetics of the upper atmosphere. This makes NO…
Blazars, radio-loud active galactic nuclei with the relativistic jet closely aligned with the line of sight, dominate the extragalactic sky observed at gamma-ray energies, above 100 MeV. We discuss some of the emission properties of these…
We considered a model for the prompt phase of Gamma-Ray Burst (GRB) emission arising from a magnetized jet undergoing gradual energy dissipation due to magnetic reconnection. The dissipated magnetic energy is translated to bulk kinetic…
The EGRET results for gamma-ray intensities in and near the Galactic Plane have been analysed in some detail. Attention has been concentrated on energies above 1 GeV and the individual intensities in a $4^\circ$ longitude bin have been…
Gamma Ray Bursts (GRBs) are among the most powerful sources in the Universe: they emit up to 10^54 erg in the hard X-ray band in few tens of seconds. The cosmological origin of GRBs has been confirmed by several spectroscopic measurements…
Gamma-Ray Bursts (GRBs) have been detected at GeV energies by EGRET and models predict emission at > 100 GeV. Milagro is a wide field (2 sr) high duty cycle (> 90 %) ground based water Cherenkov detector that records extensive air showers…
A complete model for the origin of high-energy >~10^{14} eV) cosmic rays from gamma-ray bursts (GRBs) and implications of this hypothesis are described. Detection of high-energy neutrinos from GRBs provide an unambiguous test of the model.…
Gamma-ray bursts are flashes of high-energy radiation lasting from a fraction of a second to several hours. Military satellites made the first detections of GRBs in the late 1960s. The $\gamma$-ray emission forms from shocks in a…
We present a state-of-the-art scenario for newly born magnetars as strong sources of Gravitational Waves (GWs)in the early days after formation. We address several aspects of the astrophysics of rapidly rotating, ultramagnetized neutron…
We discuss some the effects of local gamma-ray bursts on the earth's atmosphere. A rough calculation of the fraction of ozone destruction by catalytic $NO_{x}$ cycles is given, which in turn serves to argue how the large flux of gammas from…