Related papers: Gamma-ray emission from massive star forming regio…
Recent observations suggest that gamma ray bursts (GRBs) and their afterglows are produced in star formation regions in distant galaxies by highly relativistic jets that happen to point in our direction. Relativistic beaming collimates the…
In this paper we model the emission from a relativistically expanding electron-positron pair plasma fireball originating near the surface of a heated neutron star. This pair fireball is deposited via the annihilation of neutrino pairs…
Recent results, the present status and the perspectives of high energy gamma-ray astronomy are described. Since the satellite observations by the Compton Gamma Ray Observatory and its precursor missions have been reviewed extensively,…
Protostellar jets are present in the later stages of the stellar formation. Non-thermal radio emission has been detected from the jets and hot spots of some massive protostars, indicating the presence of relativistic electrons there. We are…
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.…
We argue that gamma-ray bursts (GRBs) may be the origin of the cosmic gamma-ray background radiation observed in GeV range. It has theoretically been discussed that protons may carry a much larger amount of energy than electrons in GRBs,…
Jets are ubiquitous in the Universe. They are collimated outflows whose origin is associated to an accretion disc and a central object, and can be very powerful non-thermal emitters. Jets form in active galactic nuclei, gamma-ray bursts,…
Fermi has discovered two giant gamma-ray-emitting bubbles that extend nearly 10 kpc in diameter. We propose that periodic star capture processes by the galactic supermassive black hole, Sgr A*, with a capture rate $<10^{-5}$ yr$^{-1}$ and…
When gamma-rays emerge from a central source they may undergo Compton scattering in surrounding matter. The resulting Compton-scattered electrons radiate. Coherent radiation by such Compton electrons follows nuclear explosions above the…
Adopting the convection-diffusion model for energetic electron and proton propagation, and accounting for all the relevant hadronic and leptonic processes, the steady-state energy distributions of these particles in the starburst galaxies…
We compute the attenuation of gamma-rays from remote quasars due to interactions with ambient low-energy photons produced by stars in galaxies and show that the next-generation gamma ray telescopes can probe the cosmic star formation rate…
We present a study of the radio emission from a massive runaway star. The star forms a bow shock that is clearly observed in the infrared. We have performed VLA observations under the assumption that the reverse shock in the stellar wind…
The middle-aged supernova remnant (SNR) W51C is an interesting source for the interaction of the shell with a molecular cloud. The shell emits intense radio synchrotron photons, and high-energy gamma-rays from the remnant have been detected…
Presently there are several classes of detected gamma-ray extragalatic sources. They are mostly associated to active galactic nuclei (AGN) and (at soft gamma rays) to gamma-ray bursts (GRB), but not only. Active galactic nuclei consist of…
Galactic cosmic rays are commonly believed to be accelerated at supernova remnants via diffusive shock acceleration. Despite the popularity of this idea, a conclusive proof for its validity is still missing. Gamma-ray astronomy provides us…
It is proposed that TeV gamma-rays and neutrinos can be produced by cosmic rays (CRs) through hadronic interactions in the innermost parts of the winds of massive O and B stars. Convection prevents low-energy particles from penetrating into…
We report the detection of high-energy gamma-ray signal towards the young star-forming region, W40. Using 10-year Pass 8 data from the Fermi Large Area Telescope (Fermi-LAT), we extracted an extended gamma-ray excess region with a…
It is proposed that the gamma-ray photons that characterize the prompt emission of Gamma-Ray Bursts are produced through the Compton drag process, caused by the interaction of a relativistic fireball with a very dense soft photon bath. If…
Young, low-mass stars are luminous X-ray sources whose powerful X-ray flares may exert a profound influence over the process of planet formation. The origin of such emission is uncertain. Although many or perhaps most recently formed,…
The recent reports of temporal and spectral peculiarities in the early stages of some afterglows suggest that we may be wrong in postulating a central engine which becomes dormant after the burst itself. A continually decreasing postburst…